eilat' coral reefs

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Eilat’s Coral Reefs Jacob Dafni The last decade has brought new dangers to the coral world. Global warming, coral bleaching, over-exploitation, pollution and careless coastal development have affected almost all coral reefs and sites around the world. Eilat’s reefs have been spared the notorious bleaching effect, due to lower seawater temperatures, but human-related stresses affected the reefs of the Gulf, where scientists have recorded a notable decline of the diversity and degradation of coral reefs in the northern Gulf of Aqaba. Nonetheless, these reefs still show a high diversity of corals and reef organisms. The text and pictures included in this book are testimony to the rich and diverse fauna of Eilat’s coral reefs. Most of the photographs included in the book were taken there during the last 5 years. Nowhere in the world do coral reefs exist in such proximity to a fast-growing city, to an oil port and to tourism-related development projects, and their mere preservation is a stimulating challenge. We believe that increased local awareness and utmost dedication of the community will ensure the survival of Eilat’s coral reefs against all odds. Dr. J. Dafni, a marine biologist who has been studying the northern Gulf of Aqaba for almost a half of a century, started his work there as a local guide for the Society for the Protection of Nature. He served initially as a warden in Eilat’s Coral Marine Reserve, and later, during his Master’s and PhD studies, explored the diversity and morphology of marine animals in polluted sites. In his scientific and educational career, as a teacher of marine studies and as a director of academic studies in a local college, he has never abandoned his faith that coexistence between urban development for the benefit of man and nature preservation is possible. Dr. Dafni’s previous book, “The Gulf of Eilat, from the Red Sea to the Red Line”, published in 2000 in Hebrew, is a comprehensive source book and an account of the natural and human history of the Gulf shared by four countries. The present book is an updated pictorial summary of the coral reef and adjacent habitats, within the boundaries of Israel’s coast. Cover photographs: The colorful diversity of Eilat’s coral reef fauna Photographers: I. Ben-tov, J. Dafni, M. Levin, D. Weinberg Ye’ela Publishers 972-523-854981 Jacob Dafni Eilat’s Coral Reefs Photography: J. Dafni M. Levin & Divers of the “Tapuz” Diving Forum To buy Dr. Jacob Dafni's book Press here

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Eilat, in the northernmost reach of the Red Sea, the Gulf of Aqaba, accomodates a highly diversed, and an ecologically endangered coral reef community. This book is an optimistic view of this underwater treasure. All the UW pictures were taken during the last 5 years. Dr. Jacob Dafni is a marine biologist, concerned by the challenge of coexistence between pristine nature and human activities.

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Page 1: Eilat' Coral Reefs

Eilat’s Coral Reefs Jacob Dafni

The last decade has brought new dangers to the coral world. Global warming, coral bleaching, over-exploitation, pollution and careless coastal development have affected almost all coral reefs and sites around the world. Eilat’s reefs have been spared the notorious bleaching effect, due to lower seawater temperatures, but human-related stresses affected the reefs of the Gulf, where scientists have recorded a notable decline of the diversity and degradation of coral reefs in the northern Gulf of Aqaba. Nonetheless, these reefs still show a high diversity of corals and reef organisms. The text and pictures included in this book are testimony to the rich and diverse fauna of Eilat’s coral reefs. Most of the photographs included in the book were taken there during the last 5 years.

Nowhere in the world do coral reefs exist in such proximity to a fast-growing city, to an oil port and to tourism-related development projects, and their mere preservation is a stimulating challenge. We believe that increased local awareness and utmost dedication of the community will ensure the survival of Eilat’s coral reefs against all odds.

Dr. J. Dafni, a marine biologist who has been studying the northern Gulf of Aqaba for almost a half of a century, started his work there as a local guide for the Society for the Protection of Nature. He served initially as a warden in Eilat’s Coral Marine Reserve, and later, during his Master’s and PhD studies, explored the diversity and morphology of marine animals in polluted sites. In his scientific and educational career, as a teacher of marine studies and as a director of academic studies in a local college, he has never abandoned his faith that coexistence between urban development for the benefit of man and nature preservation is possible.

Dr. Dafni’s previous book, “The Gulf of Eilat, from the Red Sea to the Red Line”, published in 2000 in Hebrew, is a comprehensive source book and an account of the natural and human history of the Gulf shared by four countries. The present book is an updated pictorial summary of the coral reef and adjacent habitats, within the boundaries of Israel’s coast. Cover photographs: The colorful diversity of Eilat’s coral reef faunaPhotographers: I. Ben-tov, J. Dafni, M. Levin, D. Weinberg Ye’ela Publishers 972-523-854981

The last decade has brought new dangers to the coral world. Global warming, coral

Jaco

b D

afni

Eila

t’s

Cor

al R

eefs

D. Weinberg Ye’ela Publishers 972-523-854981

Photography: J. Dafni M. Levin& Divers of the “Tapuz” Diving ForumTo buy Dr. Jacob Dafni's book

Press here

Page 2: Eilat' Coral Reefs

1

שוניות האלמוגים של אילתבמבט אופטימי

Eilat’s Coral Reefs© 2008 Jacob Dafni

All rights Reserved By Ye’ela Publishers 2008 P.O.B. 14677, Eilat Israel 88580

All rights reserved. No part of this publication may be reproduced, stored in a retrieval system, or transmitted in any form, or by any means,

electronics, mechanical, photocopying, recording or otherwise, without the .prior permission of the copyright holder

ISBN 978–965–91252–1–0Printed in Israel 2008

Photography:J. Dafni, M. Levin

and Divers of the “Tapuz” Diving Forum

Eilat’s Coral Reefs Jacob Dafni, PhD

Ben-Gurion University, Eilat Campus

Graphic Design: Lior Dafni Cover Design: Lior Dafni

Printed and bound by El-Dan, Eilat

Website: http://www.dafni.com/dafni-sites

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Groupers 116Basslets or Goldies 117 Butterflyfishes 118Angelfishes 120Damselfishes 122Wrasses 124Cleaning stations 126Parrotfishes 128Goatfishesandcompany 130Hawkfish 131FloundersandSoles 132Keepingalowprofile 133Blennies 134Gobies 136Gobiesandothersmallfishes 137Surgeonfishes 138Rabbitfishes 140Sea breams 141 Nocturnalfishes 142Sweeperfishes 144Living in the current 145 TriggerfishesandFilefishes 146Trunkfishes 148Porcupinefishes 149Pufferfishes 150Pearlfishes 151Anglerfishes 152Onthesandandbeneath 153Sea turtles 154Dolphins and Whales 155 7. Pollution and human effect 156 High and low diversity 157 Pollution types and effect 158Coral predation 159 Artificialobjects 160Species dynamics 164Coral nursery 165Artificialreefs 166Ship wrecks 169Underwater photography 170Diving sites 171 Eilat Coral Nature Reserve 172Underwater Observatory Marine Park 174The “Dolphin Reef” 176Underwater restaurant 177Um-Rashrash Educational Coral Reserve 178Eilat’s coral reefs in the 21st century 180Endnotes 182 Further Reading 183Glossary 184Indices 186Photo credits 190

Contents1. Introduction 4 Preface 6Genesis 82. Habitats of Eilat’s coast 10Tide and intertidal 10Coral reef 12The lagoon 16The open sea 183. Algae and lower animals 20Algae and seaweeds 20 Sponges 22 Cnidaria - Hydrozoa 24 Jellyfishes 264. Corals, variety 28 Coralmaindivisions 30Coralasabiotope 31Reefcoralstaxonomy 32Factsoncorals 35Coralforms 36-52Hermatypiccorals 53Ahermatypic corals 54Soft but not Soft Corals 59Soft Corals 60-65Gorgonians and Fan corals 66Sea Pens 68Organ-pipe Coral 69Sea Anemones 705. Invertebrates 74Worms 74Mollusca 76Shell-bearing snails 76Nude snails 80Bivalves 82Squid and Octopus 84Shrimp and Crabs 88Echinodermata 90Sea Stars 92Sea Urchins 94Sea Cucumbers 96Brittle Stars 98Feather Stars 99Tunicates 100 Hemichordates, acorn worms 1016. Reef fish & Vertebrates 102 Coralfishes 103Sharks 104 Skates and Rays 106 Fishes as predators 107 Eels and Moray eels 108Seahorse and relatives 110 Pegasus 112 Lionfishes 113ScorpionfishesandStonefishes 114

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About this BookThe aim of this book is to remind the reader of the presence of a living and active wildlife resource intheshallowwateradjacenttotheurbanregionoftheCityofEilat.Thisnaturalresourcesufferedconsiderabledamageduringthelastfewdecades,firstlybecausethemainconservationeffortswere concentrated on the 1.5 km stretch of the Coral Nature Reserve coast. Secondly, it was the common conviction of the local and national population that “there is nothing to see underwater in Eilat - everything is already gone”. In recent years, while investing special efforts to regulate the unprecedented large numbers of divers (who did not accept this doomsday prophecy), and to reclaim the neglected and dwindling reefs, it became evident that it is in fact possible to rehabilitate much of the damaged reefs and to establish a sustainable development program for the northern tip of the Gulf and its Eilat beaches. This includes enforcing of environmental protection regulations, and insertingartificial structures thatwill increase the shallowwater capacity forfishandothermarineorganismsandofcoursebenefitthedivers.Thisbookaimstoadvertisethisblessed activity. The reader will find in this book a description of the habitats and their living organisminhabitants, and will see them as well as read about them. Various topics such as geological background, reef formation, tide,currentsetc.willbementionedbrieflyineveryman’slanguage,withoutburdeningthereaderwithtechnicaldetail.Scientifictermsmarkedinitalicsareexplainedin a short glossary at the book’s end. I am convinced that knowledge increases awareness, and public awareness is vital for the struggletopreservethemarineenvironmentforourbenefitandthatofourchildrenfordecadesto come. ThetouristwillfindhereaconcisebodyofknowledgeabouttheoriginoftheRedSea,itsgeology, climate and tide regime. The diversity of coral colonies and their contribution to the reef is discussed, with emphasis on the organisms that reside amongst them in the reef and its environment, with abundant pictures, most of them taken in the last 5 years. Nevertheless, it is not aguide.Youwillfindareferencelistofbooksandguidesforplants,invertebratesandfishattheend of the book. My previous book “Gulf of Eilat, from the Red Sea to the Red Line”, published in Hebrew in 2000 is a comprehensive account of the natural and human history of the Gulf and the northern Red Sea. Some of the included information has been incorporated into the present book. Identificationofmanyorganisms,especially invertebrates, isnotalwaysassimpleas it isgenerally believed, since it must be done by experts for each and every taxonomical group, using subtle microscopic details. A special effort was done to establish the identity of most of the described species. I have also created an internet guide for the invertebrates of the Gulf of Aqaba (Eilat). It contains a collection of ca. 1200 species of corals, molluscs, sponges, worms, crustaceans and echinoderms. The reader is encouraged to use it: www.dafni.com/dafni-sites:Nevertheless,manyscientificnames are arbitrary, waiting for taxonomists’ decision* J. Dafni

Corals and Fishes in the coral reef

Coral reefs are the most diverse and beautiful of all marine habitats. Photo: J. Dafni, M. Levin

* In uncertain scientific identifications youmay often find the abbreviation cf., meaning “confer”, or “compare with”. The abbreviation sp. means that only the genus is known, and spp. meansthatseveralspeciesmaybeincludedwithinthisidentification.

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Preface Eilat is an ever-growing city with over 60,000 inhabitants. It was established in 1949, one mile west of the historical site of Biblical Eilat,intheJordaniansideoftheborder.Duringitsfirsttwodecades, the town’s economy was based on copper mining in the surrounding desert, as well as on the development of a southern port for the state of Israel. An initiative to develop commercial fishingintheGulfofAqabafailedbecauseofthelimitedleveloforganicproductivityintheGulfof Aqaba. In the mid 1960’s Eilat entered a new era as a tourist resort. Blessed by the relative warmth of the desert winter, the cool and blue waters of the Gulf, and of course the lavish and colorful coral reefs, Eilat has gained a worldwide reputation. A small stretch of shore was destined tobeoneofthefirstcoralreefnaturereservesintheworld.MarinebiologicalresearchandtheUnderwater Observatory Marine Park, established in 1975, brought millions of spectators closer to view and observe the seascape, and many scientists carried study of the coral realm. SCUBA diving and snorkeling are both well developed in Eilat and its neighboring towns. The last decade has brought new dangers to the entire coral world. Climatic and human activities unite to cause global warming, coral bleaching; over-exploitation of fish and othermarine organisms, pollution and non-sustainable coastal development affected almost all coral reefs and sites around the world. In Bali, Indonesia, a world famous coral reef resource, only 6 percent of the reefs are now in healthy condition. The Eilat reefs have been spared the notorious bleaching effect, but a dispute has been raging for years regarding the possible deleterious effect of cage-basedmariculture of fish near thenorthern shore of the Gulf, where many scientists have recorded a notable decline of the coral reef in the entire northern part of the Gulf of Aqaba. The appearance of coral reefs here is no less of a miracle. Favorable climate, clear water and other environmental factors turn the coral reefs into an underwater oasis in a nutrient-poor sea, justlynamedbymarineecologistsa“bluedesert“.Though,thecontentandpicturesincludedhereare testimony to the rich and diverse fauna and flora of the underwater environment of Eilat. Most of the pictures included in this book were taken during the last 5 years at Eilat reefs. Although we screened out many pictures showing damage and deterioration in the different habitats, the potential for healing is there, and measures combined with self-restraint of shore development entrepreneurs and divers will pay dividends in the future. Presently, measures taken by the Nature Reserve Authority, such as closure of certain protected areas and strict rules imposed on divers, are already showing results, but dangers still exist. We face the challenge of preserving this underwater bounty for the generations to come. We believeinthecapacityofEilat’scoralreefstoflourish.Againstallodds,thecoralreefsofEilatshould survive.

Sea and Life Life depends on water, and in the sea, water is quite common. A miraculous form of matter, water is the only compound found on Earth as solid (ice), liquid and gas (steam). Sea water is the cradle of life on Earth. Water absorbs the sun’s energy on summer days, warming the Earth; Water also radiates its heat to warm the air at night and throughout winter, and cools the air during daylight hours in the summer. Weather is all about water and air. Solar radiation causes evaporation, and in higher altitude thewaterliquefies,formingcloudsthatwillbecarriedaboutbywinds,andultimatelydroptheircharge as rain or snow. Eilat, due to its warmer air, gets very small quantities of rain and can be definedasadesert. In the warm climate of Eilat, rain and wind storms are very rare, and the climate is mild. Although in summer temperatures rise to 450C, in the low humidity the heat is less inconvenient than in humid regions. Once or twice a year, southern wave storms hit the northern part of the Gulf. They usually last several hours (picture). Billions of years ago in the sea, chemical molecules arranged themselves into a simple organism,whichwasabletoexploittheearth’smineralresourcesandreproduce:thefirstlivingcreature. A further ‘invention’, photosynthesis, in plants, is the most important life-sustaining process in evolution: a unique molecule – chlorophyll – traps solar energy and turns carbon dioxide, a waste material, into glucose, the basic sugar that builds the living tissue of plants and is consumed by all animals along the food chain. Water takes an important role in this process.

Sea water is always on the move. Solar energy that warms the sea causes it to form currents that shift water masses from the warm tropics to the high latitudes, thus making human life there possible. Colder water currents move back to the tropics, sinking to the abyss. Due to topographic conditions – shallow sills in the southern entrance to the Red Sea – colder deep water does not enter it, and therefore its water temperature never drops below 200C (820F). Sea level is constantly changing. The gravitational pull of the sun and the moon causes sea level to rise in high tide, and drop down at low tide, six hours later. In Eilat, the tidal range is about1meter(3.3feet)atmost.Seasonallow tides cause the sea level to drop further and the coral reef top is exposed and many corals may die.

Southern storm waves hitting Eilat northern beach. Photo: M. ChenPhoto: J. Dafni

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האיור ממחיש את שלבי היווצרות ים-סוף ומפרציו. תחילה היה זה עמק בקע יבשתי, שבו סוואנות אך קדום, ים-סוף שיצרו התיכון, הים מכיוון לבקע מי-הים פרצו בהמשך טרופי. וצומח חי ועולם מאוחר יותר ניתק הקשר הזה ומימי האוקיינוס ההודי נכנסו מדרום והפכוהו לים טרופי. כיאות לים שנוצר על בקע גיאולוגי, ים-סוף עמוק מאד. עומקו מגיע ל-3,500 מ’. מוצאו לאוקיינוס, במצר באב-אל מנדב, הוא צר, רוחבו כ-25 ק”מ ולו מפתן רדוד, שעומקו אינו עולה על 130 מ’. מפרץ אילת הוא “מיני ים-סוף”, שרוחבו קטן מ-20 ק”מ אך עומקו 1860 מ’. עומקם של מצרי טיראן, במוצא מפרץ אילת לים-

סוף, רדוד יחסית, כ-250 מ’. בהמשך נראה כי לתכונות אלה חשיבות רבה בקביעת אופיו של הים. הים מי בטמפרטורת שינוי שיש לכך גורם דרום-צפון הכללי שכיוונו סגור ים ים-סוף של היותו הממוצעות. בקיץ, טמפרטורות המים בדרום ים-סוף כ-30 מעלות צלסיוס, ואילו באילת רק 26 מעלות. בחורף ירידת חום המים )ל-20 מעלות( בצפון ים-סוף ומפרציו יותר קריטית, שכן טמפרטורת מים נמוכה מזו איננה מאפשרת קיום שוניות אלמוגים. כמו כן, ניכרת עלייה במליחות מי-הים לאורכו של ים סוף. בעוד שבדרום היא כמליחות מימי האוקיינוס – 3.5%, בצפונו ובמפרץ אילת היא מגיעה לכדי 4.1%. זוהי המליחות הגבוהה ביותר בגוף מים המחובר לאוקיינוס. לשני אלה, הטמפרטורה והמליחות, השפעה להתקיים מסוגל הטרופי-ימי והצומח החי כל לא ומפרציו. בים-סוף והצומח החי תפוצת על רבה

בטמפרטורות ומליחות כה קיצוניות. בעידן הרביעון )במיליון השנים האחרונות( עברו על כדור הארץ כמה תקופות קרח, שהתבטאו בירידה להתכסות ואסיה, אירופה אמריקה, בצפון נרחבים לאזורים וגרמו בממוצע, חום מעלות כ-4-5 של בשכבות קרח, שנגרע ממי האוקיינוסים והוריד את מפלס המים בהם בכדי 130 מ’ בשיאן של תקופות אלה. ירידת מפלס המים בים-סוף אל גובה המפתן הרדוד שבפתחה גרמה לחסימה חלקית או מלאה של כניסת מי-ים לאגנו. חסימה זו, וההתאדות הרבה הנובעת מהקרינה וחום המדבר הגובל בו, גרמו

להתייבשות של ים-סוף – משבר שהתבטא בהכחדה מלאה או חלקית של החי שבו. עליית פני-הים האחרונה, שחלה לפני כ-6000 שנה, הביאה לתחייתו של הים. בעלי החיים והצמחים שחיו בו לפני המשבר, ומצאו מחסה בים הערבי, הסמוך למוצא ים-סוף, חזרו ואכלסו את הים כששבו

התנאים המיטביים לשרור בו. חלק משוניות האלמוגים בחוף האלמוגים של אילת הן שוניות קדומות, שמתו בעת המשבר והתחדשו בעקבות עליית מפלס הים. יש לזכור שירידה של 130 מ’ במפלס מי המפרץ סמוך לאילת שינתה את מפת החוף מאד באותה תקופה, והותירה את רישומה על הנוף שנקבע מאוחר יותר. החוף שנחשף אז התרחב והעמיק מאד, והנחלים שנשפכו לתוך המפרץ חרצו בו קניונים עמוקים, שחלקם מהווים כיום

חלק מהטופוגרפיה התת-מימית, נופים תת-ימיים שהם יעדי צלילה מבוקשים.

צילום: י. דפני

ים ומדבר נפגשים בראש מפרץ אילת

Genesis: How it came into being All open seas are interconnected directly or through sea straits. Therefore a change in one sea affects other water bodies, either directly or indirectly. Eilat is situated at the remotest end of the Red Sea, in the northern Gulf of Aqaba (Gulf of Eilat). One glimpse at the map may reveal much of the structure and origin of this sea, and the processes that created its shape and nature. It is common knowledge that the Red Sea is part of the geological rift system formerly known as the “African-Syrian Rift”, a geological process that undoubtedly touched the early history of mankind that evolved in Africa and spread to other parts of the globe. We will discuss here in short these pre-historicevents,andfigureouthowtheyaffectedthemarineenvironmentofourarea. Africa and the Arabian Peninsula are shreds of a larger tectonic plate that tore and its pieces -AfricanandArabiantectonicplatesdriftedapartasmuchas300km,inthe“Red Sea Rift”, for atleast35millionyears.Therateofcontinentaldriftistoosmalltoperceivevisually,anannual3-5cm,butifmultipliedbythemillionsofyearsthathaveelapsed,thewidthoftheRedSeaiseasily explained.

ThetopographyoftheArabianandAfricancoastsandtheobvious‘fit’-landheadsagainstbays in the other side - is a convincing evidence to such tearing. Geologists believe that the RedSeaistheearlystage,manifestationofanewocean,whichwillreachitsfinalsizemillionsof years from now. Like most rifts, the Red Sea Rift has a smaller rift connected to it, which separates the small Sinai Plate from the Arabian Plate. It is called the “Dead Sea Rift”. Unlike

Desert and sea meet in the Gulf of Eilat (Aqaba)

Four stages in the creation of the Red Sea and its Gulfs. After S. Marco (1986). Photo: J. Dafni

The Red Sea Rift, the Dead Sea Rift is a transform rift, meaning that land masses along this rift do not split, they move horizontally alongside each other in a “strike-slip” fault. The Arabian Plate moves northwards and the Sinai plate is shifted to the south, in a movement that accounts for about 105 km over the course of the last 20 million years. The Dead Sea Rift extends all the wayfromtheGulfofAqabathroughtheAravaDesertandtheJordanValley,formingseafloordeeps and the terrestrial basins of the Dead Sea and other lakes. The attached picture illustrates this process. Initially, the Red Sea was a terrestrial rift valley, like the present time African rift valley.Latertheseainvadedfromthenorth,andfinallythenorthernconnectionwasclosedandthe Red Sea became an extension of the Indian Ocean. TheRedSeabasin is3,500mdeep,but itsopening to theGulfofAden isnarrow,25km,andshallow,only130mdeep.TheGulfofAqaba–1860mdeep,hasalsoanarrowandshallowopening, whereas the Gulf of Suez is shallow throughout – only 80m deep. These properties deeply affect the oceanographic nature of the Red Sea. Being an enclosed sea with a south-north orientation explains the summer temperature decline,from300Cinthesouth,to260Cinthenorth,droppingaslowas200CinEilatduringthe winter (nearing the lower limit for coral reef existence). A similar gradient in the salinity brings the Gulf of Aqaba next to a world record for oceanic seawater – 4.1%. Temperature and salinity are both factors which limit the distribution of Indian Ocean fauna and flora along the Red Sea, and the cause for the high proportion of endemicspecies(upto50%inseveralfishfamilies). In the Quaternary Period the Earth underwent several glacial periods (ice ages), when average global temperature dropped by several degrees Celsius, causing seawater to cool and ice to accumulate in the world’s temperate regions. During the glacial periods the land surrounding the Red Sea became more arid than before, and the meager supply of rain or river water to the seastopped,whileevaporationsloweredtheseawaterlevelbeyondthe130msill,connectingtheRed Sea with the Gulf of Aden. It is believed that the Red Sea became partially or totally isolated, possibly dried out and salt accumulated in its bottom. In the inter-glacial periods, between the glacials, seawater level rose again, and connection with the ocean resumed. It is assumed that inthelasticeage,12,000-15,000yearsago,sealeveldropped130mbelowpresentlevel.Themore recent return of the sea, some 6,000 years ago, brought back most of the animals and plants, which sheltered in the Gulf of Aden and the Arabian Sea throughout the climatic crises, which is reflectedbythehighrateofendemism.ItisalsobelievedbysomescientiststhatEilat’scoralreefsarerejuvenatedpre-IceAgereefs.ThelatestIceAgetopographyhasbeentransformedintosomebeautiful underwater canyons and other attractive diving sites.

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Habitats: Tides and intertidalThe phenomenon of cyclic oscillation of water level, the tide, is known in all marine and estuarine shores. The link between the water level and phases of the Moon and Sun has been known since ancient times. Observations show that high or low tide peaks lag by 52 minutes from one day to the next, and that highest vertical tidal extension appear in the beginning of the lunar month (as in the Hebrew calendar, which is based on the phases of the moon), and two weeks later, when both the Moon and Sun, are in a straight line relative to Earth and their gravitational forces combine.

The intertidal zone is your introduction to the marine realm. It is a “hybrid” between marine (in high tide) and terrestrial habitats (in low tide). For marine organisms the intertidal zone is a forbidding terrain. They face twice daily extremely different conditions on a twice-daily cycle - being submerged at high tide, and totally exposed to strong solar radiation and dry air heat and high salinity several hours later when the water fall down. Furthermore, they have to withstand frequently strong wave conditions. On the other hand, the animals that adapted to inhabit the intertidal zone are less threatened by competition from other marine animals and usually develop larger populations. Generally, the intertidal zone has a much lower diversity of organisms than the submerged zones.

Intertidal rocks and tide pools

* Here, and throughout the book, the order of the pictures – if not stated otherwise – starts in the upper left, and continues in a clockwise direction.

Animals in the intertidal beach rock and pools*: Chiton (Acanthopleura vaillantii), Barnacles (Tetraclita squamosa), preyed upon by Whelks (Thais hippocastanum), Common Limpet (Cellana eucosmia), Polished Nerita (Nerita orbignyana), Mangrove Prawn (Palaemon debilis), Blennid fish (Istiblennius edentulus). Photo: J. Dafni Rocky Intertidal zone at Eilat: tide pools and beach-rock habitat. Small pictures: Shore Brittlestar (Ophiocoma

scolopendrina), Shorecrab (Metopograpsus messor) and Periwinkles (Nodilittorina subnodosa) at low tide, climbing on top of each other to escape the scorching heat of the rock. Photo: J. Dafni

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Habitats: Coral ReefThere are no creatures that better represent the shapes and colors of the underwater tropical habitat’s diversity than corals.The ‘living flowers’ roles extend far beyondmere beauty andsplendor - they make up the underwater habitat itself. The evolution of corals started a half a billion years ago, and is still acting constantly. Coral individuals are called polyps. They reproduce both sexually, by emitting eggs and sperm into the water, and asexually, by division of polyps which remain clumped together to form colonies. The colonies, with their many identical polyps, may endure for thousands of years with no substantial change in their DNA content. Coral polyps, especially the Hexacorallians, form a communal or colonial solid limestone skeleton that remains intact after their death, and which should become, part of the unique sedimentary rock – the coral reef. If we only could go back in time and visit the Tethys Ocean 200 million years ago, we could meet similar underwater reefs, which limestone secretions comprises the mainframe of many of the present-day’s mountain ranges. The key to this evolutionary success is, no doubt, their cooperation with monocellular algae, the zooxanthellae, which entered their host’s tissues eons ago, and established with them symbiotic relationships that enables the corals to free themselves from complete dependence on external food sources, i.e. predation. On the contrary, many corals – through their algal partners – produce more food than they consume, the surplus of which feeds the surrounding fauna - worms, shrimps, mollusks, etc. Even if we ignore the corals’ cooperation with the algae their trapping of atmospheric greenhouse gas CO2 into their skeletons and ultimately into the reefs, we are still amazed by the richness and diversityoftheirspeciesthatmakesupthecoreofthetropical“jungle”ofthesea. The existence of a coral reef ecosystem in the northern Gulf of Aqaba is remarkable. Favorable climate, clear water and other environmental factors turn the coral reefs into an underwater oasis in the nutrient poor “blue desert”. The cooperation between corals and internally active algae enables them to flourish and sustain thousands of species of fish and invertebrate animals ofgreat diversity. They exhibit an ideal answer to the challenge of living and prospering in an impoverished sea.

What is a coral - What is a reef? 1. A coral is a kind of small animal that reproduces asexually – by division or budding – to

formlargecoloniesofseveraltothousandsofindividualflower-likeanimalscalledpolyps, which feed on small organisms called plankton. The polyps also reproduce sexually, by either internalorexternalfertilization.Thejuvenilescalledplanules swim around for a while and settle on a solid substrate, starting new colonies. Many corals have a stony skeleton that grows gradually to immense size.

2. A reef is a geological formation produced continuously by many solid skeleton bearing organisms, whose dead skeletons later consolidate to form a solid framework that turns into a sedimentary rock.

3. Coral reef is a limestone structure made primarily by stony corals, consolidated by calcareous algae. A coral reef is usually three-dimensional, and has many fractures, crevices and caves thatprovidelivingspaceforthousandsofinvertebrateanimalsandfishes.Itisconsideredthemarineequivalentofthetropicaljungle.

4. The Reef environment is colorful, teeming with life and activity. Predator-prey relationships, symbioses between plants and animals or between animal species of different origin and modes of life, all continuously interact in order to increase their survival and creation of the next generations.

Zooxanthellae - algal symbionts of stony corals and other reef organisms. Right: coral colony and an individual polyp of the same species. Photo: H. Schuhmacher, J. Dafni

Two coral types: Hickson’s Fancoral (Anella hicksoni), a gorgonian (above), and a stony coral (Montipora cf. stilosa) displaying its violet polyps. Photo: I. Ben-Tov

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Gigantic coral colony of only one species: Boulder Coral (Porites columnaris). On the right, a large Organ pipe Sponge (Siphonochalina siphonella) protrudes from a crevice. Photo: J. Dafni Acoralreefismadeofmanycoralcoloniesofvariousspeciesandaccompaniedbyadiversefishfauna.Photo:M.Levin

Coral Colony vs. Coral Reef

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Habitats: the LagoonBetween the intertidal slope and the coral reefs of Eilat, stretches a narrow strip of shallow sand patches,strewnwithrocksandoccasionalcoralheads.Thisisthelagoon.Atfirstglance,nothingattractive appears to exist there, and the snorkeler, swimmer or diver moves through it to reach therichestpart–thecoralreefflat.Yet,thelagoonhasmuchmoretooffer.Manyinvertebrateanimals live here, but their survival depends mainly on their ability to dig into the sand and hidefrompredatorsorinthecaseofpredators,theyhavetocamouflagethemselvesinordertoapproach their prey. Footprints and other markings in the sand disclose intensive activities there, mainly at night and early mornings. The lagoon floor is partly overgrown by sea grasses, several species of grass-likemonocotyledon plants who invaded the shallow sandy areas and established there a lush cover of grass-like vegetation. Only two out of the 5 seagrass species known from the southern Gulf of Aqaba are found in Eilat shallows – Scaled Seagrass and the Oval Seagrass. The former is the main plant of the lagunar and reef front meadows, whereas the latter grows mainly around its margins.Alargevarietyoffishes–mainlyjuveniles–andmanyinvertebratesthriveamongtheseplants’ leaves.

Lagoon inhabitants

Long-spine Sea Urchins (Diadema setosum), Anemone carrier Hermit crab (Dardanus tinctor) and sand paste, emitted by an Acorn Worm (Ptychodera flava) (see page 100) hiding in the deep sand. Photo: J. Dafni

Green meadow of Scaled Seagrass (Halophila stipulacea) and Oval Seagrass (H. ovalis) (inset). Photo: J. Dafni Typical residents of the lagoon: Leather Anemone (Heteractis crispa)withajuvenileClownfish.Photo:M.Levin

Sand dwelling Comb Sea Star (Astropecten polyacanthus) markings on the sand, crawling about and righting itself after accidental overturn. Photo: J. Dafni

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Habitats: the Open SeaThe open sea is surprisingly close to the shore at Eilat. Because of the great depth of the Gulf (1860m),theouterslopeofthereefandtheexternalsandbottomflatsdescendsteeplytodeeperwater.Atadistanceof150mfromtheshore,theseafloormayalreadybe20mdeep,andyourfull attention turns towards the clear blue water. What is there to see in these waters? Towards the shore the forereefslopetowersupwardsandalongtheseaflooritselfseveralcoralheadsandreefknollsareteemingwiththousandsofsmallplankton-feedingfish. Fear of sharks? Larger sharks very seldom venture close to the shore. More frequently they visit thefish farms in thenorth shore,hoping tocatchfish strayingoutof thenets.Theonlycase of attack by a dangerous Mako Sharkwas30yearsago,andsincethentherehasn’tbeenasingle incident. All the same, be careful while swimming out to the open sea. Especially beware ofspeedboats.MorecommonfishpredatoristheBarracuda. It is quite large and its silhouette blends with the coloration of the seawater, and it wanders close to the reef, lurking for straying reeffish.Apropos sharks, onceor twice a year a loneWhale Shark, 10m or more in length swims all the way along the gulf to Eilat and can be spotted from the shore, or met in shallow water, attracting divers to touch or preferably, take pictures. It is a harmless plankton-feeding shark, and a welcomed visitor. The rarely seen Manta Ray (pages 106), another plankton-feeding cartilaginousfish, isalsoagiant,measuringover6macross its ‘wings’.Theonlyencounter Ipersonally had with this creature at Eilat was as I was aboard a commercial aircraft about to land attheEilatairport.Lookingthroughthewindow,Isawitdirectlybeneath,swimmingmajesticallyalongtheshoreatabout300mfromthebeach.

Theopenseaisaroute,alongwhichfishandinvertebratewander,withminimalcontactwiththeshore.Someopenseafishes,such as the Whale Sharksswimalongtheshore,whilereeffishpreyupontheplanktonicorganismslikethedelicateComb Jellies (Unknown sp.). Photo: M. Levin, J. Dafni Thelargestmidwatertopfishpredator,aGreat Barracuda (Sphyraena barracuda). Photo: B. Tamir

Open Sea life

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Flora: Algae and SeaweedsPlants are the foundation of all living systems. By means of photosynthesis - light energy and transforming it into organic matter – they economically sustain the entire food chain. The most common marine plants are algae, varying from microscopic single-celled algae to large, multicellular benthic algae called seaweeds. Except for the primitive prokaryotic (having no cell nucleus) blue-green algae, all algae are eukaryotic (i.e., having a cell nucleus). All algae alsolackthevascularsystem,typicaloflandplants,aswellasleaves,roots,flowersorseeds.They draw their water and minerals directly through their “skin”. Photosynthesis is carried out by organelles called chloroplasts. Since the chloroplasts’ shape and DNA structure is similar to that of the prokaryotic algae, it is believed that they evolved within the eukaryotic algae through a form of endosymbiosis. The algae are divided into divisions based on their pigments, Red algae, Brown algae, and Green algae etc. A group of one-celled eukaryotic algae, akin to the Red seaweed, are the free-swimming(planktonic)dinoflagellatesandtherelatedzooxanthellae. This last group’s role in the coral world cannot be exaggerated: They inhabit the body of most corals and many other marine organisms, carrying out their photosynthetic activity, providing their host with energy in the form of sugar and other carbon compounds. In the case of corals, they provide up to 90% of the host’s energy requirements, in return for protection and shelter, as well as their host’s respiration waste, the carbon dioxide, raw material for photosynthesis. Reef-building corals in particular depend on these endosymbionts both for nutrition and for calcium carbonate secretion. In the Gulf of Aqaba, both free-swimming algae and bottom dwelling seaweeds become abundant in the late winter and early spring, following the seasonal vertical mixing of nutrient rich water from deeper water, in the so-called Spring bloom.

A variety of Seaweeds

Green algae (Chlorophyta): Enteromorpha clathrata covering the coral reef during the spring bloom, and Saw-tooth Alga (Caulerpa serrulata) from the lagoon. Photo: M. Levin, J. Dafni

Codium arabicum, Dictyosphaeria cavernosa and Neomeris annulata – common benthic Green seaweeds in Eilat’s reefs. Photo: J. Dafni

Gracillaria sp., Asparagopsis taxiformis and Lithophyllum sp., benthic Red seaweeds in Eilat. Photo: J. Dafni

Turbinaria elatensis, Sargassum sp. and Padina gymnospora – common benthic Brown seaweeds in Eilat. Photo: J. Dafni

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Fauna: SpongesSponges (Porifera) are a diverse group of about 10,000 unique animal species, primarily inhabiting marine environments. In the past, they were mistaken for plants, because of their plant-like appearance, and their attachment to the rocks. Sponges are the oldest existing multicellular animals, and the simplest group, retaining a cellular level organization: similar cells do not combine to form tissue, and sponges have no body organs. In terms of gross morphology, sponges have no mouth or inner stomach, rather inner chambers interconnected by canals, open to the exterior. They have no muscle or nerve system, nor sensory organs. Feeding: seawater enters the body through tiny pores (ostia) in their outer surface, driven by the beating of whips (flagellae), located on specialized “collar cells” (choanocytes), that line the surfaces of chambers and the pore entrance. Food particles or micro-organisms are retained and ingested by the sponge cells. Theflowofwater through thecanal system isunidirectional, exiting through largeropenings(oscula). Sponges are either radially symmetrical or shapeless. Most sponges are supported by skeletons made up of the protein collagen and hard spicules, either calcareous or siliceous. The skeletal elements, collar cells and other cells are imbedded in a gelatinous matrix. The substance Spongin,intheformofflexibleorganicmesh,ispresentinmostlargersponges. Reproduction is either sexual or asexual. Sponges are either male or female (some are hermaphroditic). In sexual reproduction, male gametes are released into the water and enter the pore systems of its neighbors. Spermatozoa are “captured” by collar cells, which then lose their collars and transform into specialized, amoeba-like cells that carry them to the eggs. In most sponges the fertilized egg develops into a blastula, which is released into the water. The larvae may settle directly and transform into adult sponges, or they may spend some time drifting as plankton. Asexual reproduction is by means of external or internal buds, which can survive unfavorable conditions, when the rest of the sponge dies. Most sponges are highly noxious, and only a few animals, mainly nudibranch slugs (page 80), manage to overcome their poison and feed on them. Sponges may have peculiar shapes, from a simple coating of the rock to well-definedtridimensional structures. They are usually scientifically identified by the shape of theirspicules.

More Sponges

Sponges: Fire Sponge (Negombata magnifica), with its specific predator,Pajama Slug (Chromodoris quadricolor), Red Keyhole Sponge (Mycale fistulifera)withparasiticpolypsofajellyfishNausithoe sp. and Boring Sponge (Cliona vastifica) Photo: J. Dafni, M. Levin

More sponges. Grey Sponge (Crella cyathophora)acommonspongeofthelagoon,foundalsoonartificialstructuresandreefs, Tube Sponge (Siphonochalina sp.) and the Orange Sponge (Acanthella carteri). Photo: J. Dafni, M. Levin

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Cnidaria: HydrozoaFormerly known as Coelenterata, the Cnidaria are possibly the most important animals of the tropical marine environment. Including the classes Hydrozoa, Scyphozoa (jellyfish) andAnthozoa (corals and sea anemones), the Cnidaria are the most primitive multicellular animals. They appear both as colonies of sessile individuals called polyps, or in the form of a medusa. The class Hydrozoa is the most primitive cnidarian group, consisting of small solitary or colonial polyps that usually grow in subtidal areas or as marine fouling (organisms growing onsubmergedboatsandartificialsurfaceandpiers).Theyshowa largevarietyofshapesandlife-cycle forms. Most hydrozoans have an alternate stage life-cycle (not unlike the caterpillar-butterflyrelationship)–ofafeedingpolypstageandanalmostnon-feedingmodifiedstage,themedusa (hydromedusa), released to the water by the colony for sexual reproduction. Asexually, the polyps form – through budding – large colonies, that are either Leptothecata, having a solid, transparent cover (theca), into which the polyp’s tentacles retreat, or Anthoathecata, lacking this coverandthereforemoreflexibleandlessprotected.LikeallotherCnidariatheyhavestingingcells, cnidocytes, to paralyze their planktonic prey – shrimp, prawn or worm larvae, upon which the hydrozoans feed. At certain times they release to the water the hydromedusae, missioned to propagate the species by sexual reproduction. The spawned eggs and sperm develop into a planula, the typical cnidarian larva. It settles, after drifting a while in the open sea, on solid substrate, developing into a polyp. Several species are venomous to humans. The polyp stages of most hydrozoans are benthic,i.e.confinedtopermanentattachmenttothesubstrate. The hydrozoan polyps are normally overlooked by divers. They are usually small, mostly transparent, and less conspicuous than the corals or sea-anemones. In most cases they are mistaken for algae or bryozoans – other fouling organisms. The hydromedusae are rather felt than seen: at certain seasons they swarm in the water, and swimmers are stung by their piercing sting. Tubularia is an anthoathecate hydrozoan solitary polyp, while the Hydractinia appears as nude polyps covering many sea snail shells, like dense hairs or felt. Another order of the Hydrozoa is the Siphonophora. These swimming animals superficiallyresemble jellyfish,but theydiffer in several aspects. Jellyfishare singlemedusa-likeanimals,whereas siphonophores are transparent colonies made of several polyps and medusae bound together,driftinginmidwater,carriedafloatbysmallgas-filledbubbles-floats.Thelongtentaclescarry numerous stinging cells, and when they are seasonally abundant, their stinging touch is felt like whip lashes. Fortunately, our local species are less venomous than oceanic species

Hydrozoa: Division HydrocoralliaHere is a unique hydrozoan type that cannot be overlooked: the common Fire Coral. It is the only hermatypic (reef-building) hydrozoan genus. Its colonial calcareous skeleton adds to thestone-buildingeffortofcoralsandotherreef-builders.Liketruecorals,firecoralisheavilyladen with symbiotic zooxanthellae that give away their photosynthate products to its host. Typically,afirecoralhaspolypsandmedusaeinitslife-cycle,whereasAnthozoans–thetruecoralsandseaanemones–haveonlyonelifeform,thepolyp.Inaddition,firecoralhasthreepolyp types: mouthless dactylozoids that sting the prey, feeding polyps, called gastrozoids that ingest it, and the medusa-producing ampullae. As a rule, you can touch them (although it is not recommended)withyourfingertips,butbewarenottocontactthemwithyourbarechest,armor legs. Hydromedusae are released in season, at which time they reproduce and die, leaving behindtheirplanulalarvae.TwospeciesoffirecoralarefoundinEilat:Net Fire coral and Plate Fire coral. The aforementioned species, typical to the wave-beaten forereef is very sensitive to breakage by storms or humans – unwary divers and boat drivers.

Hydrozoans: Tubularia sp., solitary polyps, and Eudendrium cf. ramosum a colonial anthoathecate hydrozoan common in thelagoon,foundalsoonartificialstructuresandreefs.Photo:J.Dafni

Fire corals: Net Fire coral (Millepora dichotoma) form large colonies on the reef edge and Plate Fire coral (M. platyphylla), in the protected lagoon, the latter species is often infested by a Parasitic Barnacle (Wanella milleporae) and tube dwelling Christmas-Tree Worms (see page 47). Photo: J. Dafni

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Cnidaria: JellyfishJellyfishes belong to the Cnidarian class Scyphozoa. They are found mainly in open seas throughouttheworld.Thebodyofanadultjellyfishisbell-shaped,madeupofupto98%water.The ‘bell,’ in addition to the basic layers of epidermis and gastrodermis, consists of a thick layer ofcompactjelly, termedmesogloea. In the lower part of the bell is the mouth, surrounded by longer or shorter tentacles. Each tentacle is equipped with many stinging cells, cnidocytes, which wound or kill their prey. As their shape is not hydrodynamic, jellyfishes swim slowly by pulsing their bodies andjettingwaterfrombeneaththeirbells.Bydefinition,jellyfishareconsideredplanktonicanimals,passively drifting along, carried by the currents for long distances. They feed on fish andzooplankton paralyzed and caught by their tentacles. The mouth is used both to take in food and to expel waste. Like the hydrozoans, they practice alteration of generations, and most species start their life as planulae, developing into a polyp that divides or buds asexually, and later forms and expels plate-like ephyrae which develop into adult medusae. So, contrary to hydrozoans, whose medusae are small and inconspicuous, Scyphozoans have tiny polyps and large medusae.

Mostjellyfishhavealifespanoffewweeks;fewlivelonger.MostpelagicjellyfishinvadetheGulf from the Red Sea, form large swarms pushed northward by the tidal currents, ending their lifeeitherbybeingdevouredbyfishandturtles,orthrownashorebythewaves.

Noneof the local common jellyfishes are dangerous to humans althoughnowand then amigratingspeciesmayappearandinflictapainfulsting.TheMoon Jellyfish is the most common planktonic species, appearing in huge numbers in springtime, whereas another common species, the Upsidedown Jellyfish, belonging to the order Rhizostomae, does not have tentacles and is adapted to benthic life by turning its bell upside down and harboring large numbers of zooxanthellae closely packed in its mouth arms and many appendages around its mouth. Actually, in theadultUpside-downJellyfish themouth is closedand theanimal totallydependson thealgae’s sugar product as food.

The Nettle Jellyfish (Chrysaora sp.), is an infrequent visitor in Eilat waters. be careful - It stings! Photo: O. LedermanJellyfish:Moon Jellyfish (Aurelia aurita), and Upsidedown Jelly (Cassiopeia andromeda), at rest and turning to swim about. The dark appendages contain zooxanthellae. Photo: A. Colorni, J. Dafni

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Cnidaria: Corals Corals are the “trees” of the underwater tropical forest. All other organisms are in one way or another associated with them. A coral head is commonly perceived to be a single organism, but it actually consists of thousands of individual, genetically identical polyps, derived from asexual division or budding of a single individual polyp, that settled on hard substrate and its one-parent offspring remained attached to it. Coral species differ by their polyp size and shape, by their communal arrangement in large colonies and other related properties. The most important facts you should consider when thinking of them are: The shape of the growing colony depends on polyp type, available space, and environmental factors, like available light, currents and interaction with neighboring corals or other sedentary organisms. The same coral species may show different growth forms under different conditions. Coralclassificationistricky–lotsoftechnicaltermsareinvolved.Tomakeidentificationsimpler,we will try to arrange them in a convenient way, while conveying relevant information about them.

Hard or soft?Two main coral sub-classes exist: Hexacorallia which have polyps with six-fold radial symmetry, i.e., 6, 12, 18 or more tentacles. It includes the order of stony corals, Scleractinia, the “reef-building corals” (hermatypic).Thehardcoralpolypshaveafixedcolonyshape,andthepolypresides in a 6-fold external solid calcareous cup, either solitary or in a larger colony (this subclass includes also the skeleton-less sea anemones and the black corals). In the other subclass, the Octocorallia (=Alcyonaria), known also as soft corals, polyps always have only 8 tentacles, fringed with secondary branches (pinnules), and an internal skeleton made of needle-like spicules. They are termed, with respect to their contribution to the reef, as “non-reef builders” (ahermatypic). Several other coral families are included among the Octocorallia, namely the gorgonians, the fan corals and the sea-pens. All coral polyps are predators, catching planktonic organisms and organic debris. They withdraw back into their skeletal or dermal surface in response to movement or disturbance, protruding later to feed. The polyps of stony corals usually extend their tentacles at night to capture the zooplankton that rises up from a depth of 200-400m. During daylight most of their tentacles retract, while their algal symbionts carry on their photosynthesis.

Coral Variety

Hexacorallian polyps have 6, 12 or more tentacles, while Octocorallian polyps carry always 8 tentacles. Photo: J. DafniA typical coral reef view, displaying the variety of coral types cohabiting the same habitat: 1, Hydrocoral (Plate Fire coral), 2-6 Stony corals, 7-9 Soft corals and 10 an Corallimorpharian anemone. Photo: J. Dafni

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Corals Division: Hexacorallia vs. Octocorallia Corals as HabitatApart from being the main contributors to the coral reef framework, branched or pillar shaped coralsofferlivingspaceformanyinvertebratesandfish.Theseinhabitantshavetoovercomethestinging of the polyps’ cnidocytes that provide their security against predators. It has been proven that these inhabitants pay back their host by enhancing water circulation at night – when the algae do not produce oxygen – as well as chasing away coral predators.

Similar but different: Above, Bird’s Nest Coral (Seriatopora hystrix), a branched stony coral (Hexacoral), and Fingered Soft-coral (Sinularia sp.) (Octocoral). Photo: J. Dafni

A branched Staghorn Coral (Acropora sp.) colony shelters Christmas tree worms (Spirobranchus giganteum). Below: Coral Crab (Trapezia tigrina) and Damselfishes (Chromis viridis). Photo: L. Dafni, I. Ben-Tov, J. Dafni

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Variety of corals: FamiliesThevarietyofstonycoralsinEilat’sreefsissomethingyoudonotseeatfirstglance.Superficially, many corals look similar. Only after getting closer and paying attention to smaller details, does the immense diversity become clear. In the next few pages we will demonstrate this variety at the family level, at the genus level in one family, and among species within one genus, Favia (arrow).

Variety of corals: GeneraThe variety of stony corals in Eilat’s reefs can be perceived by looking at the various genera that make up the family Faviidae: no less than 12 different genera, with up to 15 species to each genus, totaling about 50 species. The six genera showed here exhibit well the variety of this family. For the variety in the genus Favia we will look in the next page (arrow).

Stony corals of the families Pocilloporidae, Poritidae, Mussidae, Pectinidae, Faviidae and Agariciidae. The diversity within the family Faviidae (arrow) will be shown on the next page. Photo: J. Dafni

Stony coral genera in the family Faviidae: Diploastrea, Echinopora, Erythrastrea, Goniastrea, Favia, and Platygyra. The variety within the genus Favia will be shown on the next page. Photo: D. Weinberg, J. Dafni

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Variety of corals: SpeciesFavia is a most variable genus. It shows a high similarity among its various species. We chose here to show six out of at least 15 species recorded from the Gulf of Aqaba, and Eilat’s reefs. Only a dedicated expert will be able to identify each and every species. Since I do not pretend to be a coraltaxonomist,identificationofthesecoralsisarbitrary,opentocommentsandcorrection.Thecharm of the subtle differences in relative polyp size, coloration and sculptural design achieved through evolution cannot be denied.

Facts about CoralsAfter discussing and displaying some of the morphological variability of the stony corals, it might be helpful to present the main features by which the coral genera and species differ from each other. Obviously, it will be only in short paragraphs, and illustrated in the next few pages: • Polypsofstonycoralsaredividedintosixtypesbytheircorallitemorphology(page36).• Asexual reproduction by means of accretion of new polyps occurs either inside or outside

theexistingpolyp’stentaclecircle(intra-orextra-tentacularbudding)(page36).• Sincethegroupingofspeciesisbasicallyaccordingtocoralliteshape,sometimesbranching

and prostrate colonies may be grouped together as different species of the same genus (page 37).

• Thesameprinciplecanbeobservedwithinasinglecoralspecies–andevencolony–whichmay show much different morphology in different parts of the colony or under different ecological conditions (pages 41, 49).

• Stonycoralsareeithersolitarypolypsorcolonial.Somespecies,mainlythoserelatedtothemushroom coral family, of typically solitary polyps, are actually colonial, with only several polypmouthsopenedalongalongerfurrow(page38).

• Evensolitary corallites may result from a small colony. A mushroom coral (Fungia sp.) begins sometimes as small buds on a wounded polyp that grows and breaks off to lead a free-livinglifestyle(page39).

• MushroomCoralsarenotalwaysdetachedfromthesubstrate.ThecoralgenusCantharellus, although of the same family, is known to live permanently attached to the rock, sometimes in averticalposition(page38).

• Thebranched corals are probably the most important contributors to the spatial nature of the reef.Amongtheirbranchesmanyinvertebratesandfishfindtemporaryshelterorpermanentlodging. Many of these lodgers contribute to the welfare and security of their host-coral. Coral dwellingcrabschaseawaypredatoryseastars,anddamselfishesaerate the inter-branchedspaceatnight,whichhelpsthecoraltosurviveoxygen-poorconditions(pages31).

• Somemassive coral colonies are no more than branched corals with their branches densely packed, each corallite riding on top of a ‘handle’-like branch. When the colony breaks, the individual branches are exposed (page 45).

• Mostcoloniesowetheirgrossmorphologytothetypeofperipheraldivisionorpolypaccretion.Colonies in which all corallites divide equally will result with a ball shape, whereas those that divide or bud new polyps at their margin will produce plate or fan-like colonies. The same applies to branched colonies, such as plate-like colonies of Acropora cf. hyacinthus (pages 40, 51, 52).

• Stonycoralcolorationnormallyresultsfromthechlorophyll of symbiotic algae within the coral tissue. Under low light their number increase and the coral is darker. Chromo-proteins in the coral tissues add red, yellow or blue colors that mask the algal coloration (page 41).

• Notall stonycoralsarereef builders. Unlike the reef-building hermatypic corals, corals that lack symbiotic algae, as well as soft corals with no calcareous skeleton, are termed ahermatypic, i.e. not reef builders (pages 54, 55).

• Moststonycoralsarenocturnallyactive.Duringdaylighttheirtentaclesareretracted.Afewspecies such as Goniopora and Alveopora have their polyps extended during the day (page 60)

Favia species from Eilat reefs: Favia cf. veroni, Favia stelligera, Favia cf. pallida, Favia laxa, Favia favus, and Favia cf. rotundata. Photo: J. Dafni

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Stony corals: Corallite typesThe shape of individual coral cups, the corallites, is primarily determined by their heredity as well as by their mode of asexual reproduction to form the colony. Stony corals are divided into six basic corallite types: cerioid, plocoid, phaceloid, meandroid, flabellate and hydnophorid. A further complication relates to the manner of asexual division of the polyps. It is either intratentacular or extratentacular. Intratentacular division, most typical among massive coral types, starts by deforming the round corallite into the shape of the number 8, with the appearance of a small partition inside the polyp’s tentacle circle that ultimately develops into a permanent dividing wall. A vertical section will show that they still retain this connection below the surface. In the extratentacular division, the colony produces buds outside the tentacular circle, attached to the adult polyp cup’s outer side.

Corals: Shapes of CorallitesMost of the corals’ skeletons show clearly during the day, when the polyps retract into the corallite cups. Their beauty is best appreciated when the bare skeleton is exposed. In this book we try however to concentrate on themorphology of the living tissue, just aswewould not care tocharacterize our friends by their bare skeletons. The variability among species of the same genus is well demonstrated by the genus Echinopora. The next display (below) shows the delicate morphology and color of two related species.

Polyps’ division: Intratentacular division in Favia (left) and Extratentacular budding, in Echinopora polyps (arrows). Photo: J. Dafni

Corallite types: cerioid, plocoid, phaceloid, hydnophorid, flabellate, and meandroid. Photo: J. Dafni, M. Levin, I. Ben-Tov

Variability among the Echinopora genus: Echinopora fruticulosa, branched, Echinopora gemmacea, and Echinopora forskaliana, encrusting colonies. Photo: J. Dafni

Corallites of exquisite beauty: Favia cf. pallida and Diploastrea heliopora. Photo: J. Dafni, D. Weinberg

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Types of corals: SolitaryMost coral colonies start with one initial polyp that multiplies many times to form a colony. One has to be experienced to differentiate between a species that always consists of individual polyps, and an initial polyp of a new colony. Furthermore, some seemingly single polyps are in fact small colonies with inadequate borders between the polyps. The Fungiidae are typically free-living solitary polyps with some attached relatives (next page).

Solitary corals: Mushroom coralsMushroom Corals (family Fungiidae) are free-living individual stony corals. They form at youth a small sessile stalk that breaks off after a time and the polyps emerge to live individually. They live on the shallow sandy bottom, and even on a rock or reef surface. Mushroom corals, living on sand,areabletogetridoffinesedimentsbyemittingmucus,uponwhichthesedimentparticlesare carried away. Mushroom corals also have the capacity to rehabilitate from breakage. Further, from fractures and denuded areas small stalks (called anthocauli) develop into new polyps. Fungiids are known for their ability to move across the substrate.

Solitary polyps: Cynarina lacrymalis, Lobophyllia cf. pachysepta, Trachyphyllia geoffroyi and Fungiid corals – Fungia fungites, Ctenactis echinata, and Cantharellus doederleini – the latter is an attached species of the mushroom coral family. Photo: R. Cohen, J. Dafni, M. Levin

Unusual mushroom corals: Typical Mushroom coral (Fungia fungites), serrated septa, short tentacles and a central mouth (see previous page), a mushroom anthocaulus emerging from underneath an adult corallite, Sharp mushroom coral (Ctenactis echinata) and Sandal coral (Herpolitha limax), a colony with several mouths. Photo: M. Levin, J. Dafni, A. Colorni

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Growth forms: BranchingStaghorn coral Acropora is the most common circum-tropical coral genus. Acropora includes hundreds of species, most of them branched. Their typical feature is the single large polyp, or rather corallite cup, in the tip of each branch that grows faster than the other corallites along the branch, hence the scientificname(Acro=tip,Pora=hole).Althoughtheyengageinrelations with zooxanthellae that provide them with food, they huntplanktonusing their stingingcells. In thePacificOcean,Acropora often forms ‘forests’ of long and thin branches, highly vulnerable to breakage by storm waves. In the Eilat reef they usually mingle with other species. A notable exception are plate-shaped Acropora cf. hyacinthus that inhabit the lagoon areas closed to the public in the Eilat Nature Reserve (middle lower row, picture below).

More Branched CoralsOther branched corals are Stylophora, the most common coral in Eilat’s reefs. It has rounded blunt-topped branches with ca. 1 mm wide polyps. Coloration ranges from the usual cream-yellow to pink and violet. Under shaded conditions it turns dark, due to excessive accumulation ofzooxanthellaeinitstissue.Itisthefirsttosettleinanewhabitat,offeringsheltertocrabsandfish.Theothergenus,Pocillopora, less commonly named Cauliflower Coral, is a pink or violet dense bush with thicker branches that offer less access to epifauna. Another rare coral genus of the same family is Seriatopora.Asimpliedbyitsscientificnametheneedle-holesizepolypsarearranged in straight vertical lines. Colors range from cream to pink or blue. All three genera are opportunistic, rapidly growing corals (termed r-strategists), but poor competitors, short-lived, often replaced by longer lasting K-strategist corals.

Left: live Stylophora, Pocillopora, Seriatopora and Right: Seriatopora skeleton displaying the vertical arrangement of the polyps. Photo: J. Dafni

Stylophora in illuminated vs. shaded habitat. Photo: J. Dafni

Pocillopora in a wave-beaten vs. protected habitat. Photo: J. Dafni

Environmental factors alter the shape and coloration of the coral colony. In the picture below, Stylophora, bright colored in an illuminated habitat compared with a much darker form growing in a shaded habitat (right). The effect of wave action upon two Pocillopora colonies: colony from anundisturbedbackreefhabitat(right)vs.astronglyflattenedcolonyfromawavebeatenreeffront.

Acropora is the most common branched coral genus with over 15 species in Eilat’s coral reefs. They differ both in corallite size and form and of course in the colony shape*. Photo: J. Dafni, M. Levin

* For an updated guide to the Eilat coral species: http://www.dafni.com/corals

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Growth forms: MassiveMassive or Hemisphere corals are globular or boulder-shaped coral colonies that grow only on their outer periphery. They are known to be slow-growing, and their polyps divide equally in all directions.Because of their very stable profiles and strong attachment to the substrate,they are more immune to strong wave action. Unlike the branched corals, the massive ones live longer; growing to very large sizes, and are better competitors (K-strategists). Massive corals produce annual density bands in their calcareous skeletons. The skeleton carries isotopic and geochemical tracers that can be used for age determination and reconstruction of the past sea surface temperatures (SST’s), and other seasonal climatic variables, such as precipitation and evaporation. From such evidence it was found that individual massive coral colonies may reach the age of several thousands years. Since it is known that Eilat’s reefs rehabilitated from the Ice Age sea level drop of over 100m about 6,000 years ago, it is probable that some of the oldest massive coral knolls’ age may date back to this event.

Massive coral colonies: Boulder Coral (Porites cf. lutea), Moon Coral (Favia stelligera) and a related coral (Goniastrea peresi). Photo: J. Dafni

Interaction between coralsCorals, like any other sedentary or territorial organism, compete to gain and protect their living space. Opportunistic branched corals succeed better in settlement on vacant rock. They finditdifficult,however, toavoidbeingtakenoverbyslowergrowing,sturdiermassivecorals. Ininteractions between corals of different species both rivals emit chemicals that affect their rivals’ growth and welfare, some of which are more effective than the others. Colonies of the same species are usually compatible, and in many cases merge.

Above: a massive Brain Coral (Platygyra daedalea) interacting with a Branched Table Coral (Acropora cf. hyacinthus). Itisobviouswhoiswinning.Bottom:MergingofthreeadjacentBrain Coral (Platygyra daedalea) colonies which retain their individual, somewhat different coloration. Photo: J. Dafni

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Brain CoralsBrain corals are unique in the sense that neighboring polyps share a common groove, and the entire coral head is shaped like a folded human brain. The large colonies are often termed boulder corals.

Above: Folded partitions and deep grooves characterize the various species of Brain Corals (Platygyra spp.). Below: Huge Brain corals (same genus) dominate the lagoon view, Eilat Nature Reserve. Photo: J. Dafni

Colonies: Brain or branched?Superficially,aLobed Coral (Lobophyllia) looks like a brain coral, and is named so by many divers. Only when broken is the real nature of the colony revealed: each polyp rests upon a long dead ‘handle’ which is connected at its base to neighboring polyps (hence the Hebrew name – “torch coral”). This makes it very sensitive to breakage. A single broken polyp, glued to the substrate, will rehabilitate, and regenerate a new colony. Fragmentation under natural conditions of corals and regeneration is recognized as an alternative mode of asexual reproduction.

Lobed Coral (Lobophyllia corymbosa): entire colony and broken, exposing the individual polyp ‘handles’. Photo: J. Dafni

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Growth forms: EncrustingEncrusting corals cover the rock with little or no upward growth, but rather encompass the surface upon which they grow. They might differ in their polyp size or shape, but they never rise over the substrate. It is important to note that massive or even branched corals have an initial encrusting phase, in which they form their colony’s basis. Encrusting corals have the advantage over other types in wave-beaten reefs (next page).

Above:Twoencrustingjuvenilecoralcolonies:Staghorn Coral (Acropora sp.), Tubercle Coral (Montipora sp.), center and below: Galaxy Coral (Galaxea fascicularis) with a Coral Ghostfish (Solenostomus paradoxus). Photo: J. Dafni, M. Levin

Encrusting juvenile coloniesMost massive or branched colonies have an initial encrusting stage, when the colony covers a given stretch, before starting to grow upwards. Sometimes, the entire nature of the coral is concealed by the prostrate appearance of the colony. It is more pronounced in variable shaped coral species (page 50).

Initial stages of Brain Coral (Platygyra sp.), Staghorn Coral (Acropora sp.),flatcolonyshowingbranchbuds,Boulder Coral (Porites cf. mayeri), Platygyra daedalea,andjuvenilestageofPlate Coral (Turbinaria sp.). Photo: J. Dafni

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Growth forms: ColumnarSeveral massive corals show distinct “branching” of the large colony into pillars of variable height. In the picture below such a colony is shown. In the lower part of the pillars other species of corals more adapted to lower light intensities, and sponges, settled. Larger and medium sized fishseekshelterbetweenthecolumns.Thecolumnarshapeismaintainedbyexcessivegrowthofthe upper, distal part.

Columns of Boulder Coral (Porites cf. columnaris). Photo: J. Dafni

Growth forms: FoliaceousFoliaceous corals are leaf-like colonies whose main growth increment is at its margins, thus forming thin plates that tend to fold and form curved surfaces. Most Foliaceous corals have their polypsonone(upper)sideoftheflatsurface.

Above: Plate Coral (Turbinaria sp.); Middle: Lettuce Coral (Pavona cactus). Below right: Elephant-ear Coral (Mycedium umbra), left: Cup Coral (Pachyseris speciosa). Photo: J. Dafni

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Growth forms: variable “Hybrids”The Horn coral shows much different colony shapes in various parts of the colony. Below it appears as foliose or plate shaped, whereas above it appears as branches or pillars, making it difficulttoidentifybyappearanceonly.

Vertical variability in the shape of a Horn Coral (Hydnophora exesa) colony. Photo: J. Dafni

More “hybrids”Two Lettuce corals (Pavona) also show mixed morphological characteristics. Maldive Lettuce Coral ispartlyflat foliaceous,partlycolumnar,whileanotherPavona sp. shows a buttressed foliaceous morphology.

Two growth forms of the coral genus Pavona: P. maldivensis and Pavona sp. Photo: J. Dafni

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Growth forms: LaminarLaminar corals are very thin horizontal leaf-like colonies. Corallites concentrate mainly in the upper surface. This characteristic is common to several families: Siderastreidae, Merulinidae, Agariciidae, Pectinidae etc.

Laminar colonies of various coral species: Pavona cf. varians, Merulina cf. ampliata, and Leptoseris explanata. Photo: J. Dafni

Hermatypic CoralsAll the stony corals shown above are hermatypic, participating in the construction of the coral reef, together with the calcareous products of other invertebrate organisms - mollusks, polychaetes and other skeleton-bearing animals. Calcium carbonate secreted by calcareous red algae consolidates them into a solid, geologically stable framework.

Live coral reef: the hermatypic organisms provide the framework, the symbiotic algae harness light energy to produce food, fedbyamultitudeoffishandotherreefinhabitants.Thefishseenaroundthereefusethereefasbaseforplanktonhuntingin the incoming currents. Photo: M. Levin

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More Ahermatypic coralsCorals of one order in the Hexacorallia, the Zoanthidea, are ahermatypic: they lack stony framework,butunlikeseaanemones,theyformdensecoloniesthatencruststonesandartificialsurfaces with living cover. Zoanthids are highly toxic, protecting them from being eaten by animals.

The ahermatypic hexacoral Sun Coral (Tubastrea coccinea) lives in darker undercuts and caves, and relies on plankton feeding. It is azooxanthellate, and its coloration is derived from pigments (inset: the same, with stretched out tentacles); other species of the same family, Dendrophyllidae, are Tubastrea micrantha (left) and two Cladopsammia spp. Photo: M. Levin, A. Colorni, I. Ben-tov

Ahermatypic CoralsUnlike the hermatypic corals that are the main contributors of calcareous material to the reef structure, ahermatypic corals do not contribute much to the coral reefs due to a lower rate of calciumcarbonatedeposition. In thisdefinitionare includedhexacorals living indarkercavesor in deep water, azooxanthellate (lacking the symbiotic algae that provide corals with their nutritious products), and octocorals whose main skeletal elements are calcite spicules imbedded in their soft tissue. The spicules disperse after the octocorals die, and enrich the sand with calcium carbonate. Many of the octocorals have zooxanthellae, but all the same their calcium carbonate contribution to the reef structure is negligible.

Zoanthidea: Three Eilati ahermatypic Zoanthid corals. Photo: J. Dafni

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Types of corals: Black CoralsBlack coralisatermthatdefinestheAntipatharia, another order of azooxanthellate Hexacorallia. They are either tree-like, elongated like a whip, or bent into a spiral. The living tissue may be colorful,buttheflexibledurableskeletonisblackordarkbrown.TwomaintypesoccurinEilat’sdeeper reef – Tree Black-corals and Barbed-wire black-corals. Their contribution to the reef structure is limited. Black Coral skeleton was used for the production of high quality polished black prayer beads in Yemen. It was also rumored to have been produced in old-time Aqaba.

More Black CoralsBarbed wireisthefirstimpressiondiversgetfromseeingithangingorstandingoutfromthecoralreeftowardstheopenwater.Itishard,flexibleandwiry.

Two species of Black-coral: Brown Barbed-Wire Coral (Cirripathes anguina) and Spiral Whip Coral (Cirripathes cf. spiralis). Photo: I. Ben-Tov, O. LedermanA full-size colony of Tree Black-Coral (Antipathes cf. dichotoma). Photo: M. Levin

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Coral shapes: MicroatollsMicroatolls are environmentally-induced bagel-like massive coral colonies in the lower intertidal or subtidal reef environments. Their unique shape indicates that vertical growth is constrained by frequent exposures to lowest spring tides, killing the uppermost polyps. As a result, microatolls usually grow laterally. The upper eroded surface of the colony is often densely grazed by sea urchins, limiting the settlement of algae and coral polyps. In Eilat microatolls are found mainly inthereefflatandintheinnerlagoon.Microatollsfoundindeeperwatermayindicatelowersealevel in the past. The name microatoll implies its resemblance to an atoll reef.

Shapes: Soft but no Soft coralMost corals hunt at night. Only a few, like the Flower pot Coral, extend their polyps to feed during the day, and are thereforemisidentifiedbymanyobservers as soft corals.The picturebelowshowsthattheyaredefinitelyhexacorals,likeallotherstonycorals.Thisbecomesmoreobvious when examining their solid skeletons.

Left and center: Goniopora usually has 24 tentacles, twice the number of its closest relative genus, Alveopora (right). Photo: J. Dafni, A. Colorni

Above: Microatoll, a giant Brain Coral (Platygyra sp.) eroded in its middle. Note the exposed concentric growth-line pattern, the black-spine sea urchins, and the resettlement of other coral species – small massive, branching, and soft corals. Below:upperreefflat,wheremicroatollsareusuallyformed.Photo:J.Dafni

Flower pot Coral (Goniopora sp.) is an extraordinary example of a stony coral with long extended polyps during the day. Photo: J. Dafni

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Corals division: Soft coralsSoft corals are octocorals which do not produce massive calcareous skeletons. Their rigidity is obtained by the internally-contained liquid pressure (hydro-skeleton). Unlike the stony corals that secrete an external rigid skeleton, to be consolidated with the hard bottom below, soft corals skeletons constitute of minute needles or spines called sclerites or spicules, imbedded inside theirsofttissue.Theyareconsiderednonreef-buildingcorals.Aftertheydietheirscleritesjointhe sand grains in the lagunar sand.Octocorals are divided into two main orders, Alcyonacea and Gorgonacea, and several small groups.Thesoftcoralsthriveinnutrient-richwatersorsettleuponartificialstructures,growingrapidly. Many alcyonarians harbor zooxanthellae that provide their energy requirements, and their colors are green-yellowish, the color of the symbiont. Some species overcome oxygen shortage by rhythmic pulsation of their tentacles. Gorgonians are mostly azooxanthellate, feeding on drifting food particles and plankton. Accordingly they prefer deeper water or darker caves, and their colors are brilliant.

Leather Coral (Sarcophyton sp.) shows the typical octocorallian eight-tentacle polyps emerging from its upper surface. The lower surface lacks polyps. Photo: J. Dafni

Pulsating Soft coralsSoft corals of the family Xeniidae are unique among corals because of their “pulsing“, pushing water away from the colony in a constant rhythmic motion. This action, once believed to help in catching food, is now thought to increase oxygen availability in low circulation environments.

Pulsating soft corals, Heteroxenia (above) and Xenia (Ovabunda microspiculata). Photo: J. Dafni

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Broccoli Soft coralsIt is hard to believe, but this green ‘broccoli’ is an animal, a coral. This shape is a common growth form shared by several soft coral species. Some, like the Green Broccoli Coral, are zooxanthellate, whereas other, or rather most soft corals are azooxanthellate, and of vivid colors (facingpage).Wheningoodshapetheyareswollen,maintainingverticalfirmness.Understressthey become limp and hunched.

Green Broccoli Coral (Litophyton arboreum), accompanied by a sponge and a Black coral, is commonly growing upon artificialmetalstructures,liketheoneattachedtotheunderwaterrestaurant.Photo:J.Dafni

Colored Broccoli soft corals

Red and Violet Broccoli Corals (Dendronephthya sp.), mingled with sponges, ascidians and other sedentary invertebrates at Moses Rock, Eilat Nature Reserve. Below: Close look at another broccoli coral, showing the red polyps and spicules in their transparent tissue. Photo: J. Dafni

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More SoftiesThe eight feather-like tentacles are typical of all octocorals, but in one coral, the Waving hand coral, the pinnules,orleafletsofeachtentaclearelargeandwaveinthecurrent.Apale,almostcolorless variation of the Broccoli coral is the Azooxanthellate Pallid broccoli coral. Independent of the light, it grows in darker deep water. Through the transparent ‘skin’ the calcareous spicules are clearly shown.

Pallid Broccoli Coral (Dendronephthya sp.) grows in deeper water; Waving Hand Coral (Anthelia sp) (inset) loses its zooxanthellae in aquarium. Photo: M. Levin, J. Dafni

Encrusting and BranchingLike stony corals, soft corals may show various growth forms: branching, encrusting, mushroom-like etc. They interact with each other and with stony corals to compete for living space. Chemical warfare plays an important role in this struggle.

Zooxanthllate Fingered Leather Coral (Cladiella sp.) spreading over the rreef surface competing with algae and corals for space. Tree-Coral (Paralemnalia sp.), typically showing long and dense soft digits. Photo: J. Dafni

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Octocorals: GorgoniansGorgonians deserve more elaborate attention than the few words we can offer them here. This is because their habitat is well beyond the reach of the common visitor, or even diver. The smallest ones hide in deep and dark nooks and crannies, and the large ones, deepwater gorgonians, are easilyignoredsincetheirreddishcolorsturnblackatdepthsofover30meters.Themostcommongorgonian genus in Eilat is Acabaria, with several species, mostly red, yellow or violet. The skeletonisflexible,butfeeble.Polypsareusuallywhite.

Three Acabaria species, three colors: Splendid Acabaria (Acabaria cf. splendens), Red Sea Acabaria, (A. cf. erythraea) and Fair Acabaria (Acabaria cf. pulchra). Photo: M. Levin, J. Dafni

Fan CoralsThe largest gorgonian coral colony here is the fan coral; found mainly in the lower forereef, wheretheyspreadtheirerectandflatbranchestofilteroutplanktonicorganismsfromthecurrents.Abeautifulfishspeciesinhabitingthiscoralisapointed-muzzleLongnose hawkfish (see also page131)thatfindsshelteramongthecoral’sfinebranches.

Hickson’s Fan Coral (Anella hicksoni)prefersdeeperwater(15-40m)whereitreachesthesizeof5m.Inset:typicalfishinhabitant, Longnose Hawkfish (Oxycirrhites typus). Photo: I. Ben-tov, B. Tamir

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Organ Pipe CoralThe Organ-pipe coral is an Octocoral, related to the soft corals, but is often referred to as a hard coralbecauseof itssolidskeleton.Itsscientificname,Tubipora musica, refers to this coral’s colony shape formed from many vertical calcareous red tubes bound together by horizontal platforms: the entire skeleton resembles a pipe organ. Each tube is occupied by a single polyp thatcanretractintoit,andtheentirecolonyiscoveredbyathinandflexiblehornycover.Whenits polyps are extended they entirely cover the skeletal structure. The pictures below show the red skeleton, the platforms, and the greenish polyp tentacles. It is zooxanthellate and reproduces asexually by sending extensions (stolons) and forming buds.

Organ Pipe Coral (Tubipora musica) overview: Colony and tentacles (above), with some polyps retracted, exposing the solid skeleton. Below, bare skeletons, in situ and cast ashore. Photo: J. Dafni

Sea PensSea pens are nocturnal colonial soft corals belonging to the order Pennatulacea. Unlike other Octocorallia, sea-pens’ polyps are specialized: one polyp, axial polyp, develops into a rigid, erect stalk (the rachis), with a bulbous peduncle, or “root“. Other polyps branch out from this central stalk, forming siphonozooids, water intake and feeding polyps (autozooids). The entire colony is insomespeciesfortifiedbycalciumcarbonatespicules.

The common Sea Pen (Pteroides sp.): and an unknown relative species (below). They emerge at night, retracting into the sand by morning. Photo: M. Levin

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Sea AnemonesRelated to the reef corals, sea-anemones are predatory animals differing from their stony coral relatives by (1) being predominantly solitary, although they may congregate in large aggregations, and (2) not producing calcareous skeletons. Sea-anemone sizes range from 5 mm to 40 cm. They reproduce either sexually or asexually, through division or budding. Large sea-anemones are inhabitedbyfishorshrimps,formingsymbioticrelationswiththem.

Largest vs. Smallest Sea anemonesBydefinitionseaanemonesaresinglepolyps,andaswithcorals,seaanemonesmaybeofvaryingsize. The adhesive sea Anemone is probably the largest polyp among the Cnidaria. The smallest locally are the Crab-carried Anemones, associated with small crabs that carry them in their pincers (chelae) as weapons.

Adhesive Short-arm Anemone (Cryptodendrum adhesivum) - up to 40 cm, compared to the smallest Crab Carried Anemone (Triactis producta), 5 mm across (below right, arrows) held in the pincers of a small Anemone Carrier Crab (Lybia sp.). Left: a Squat Cleaner Shrimp (Thor amboinensis) is a commensal shrimp associated with large sea-anemones and sea cucumbers. Photo: L. Dafni, J. Dafni, O. Lederman

A variety of sea anemones: Sunray Anemone (Heteractis aurora) (above) and below, right to left: Leather Sea Anemone (H. crispa), usually accommodating juvenileclownfish; Commensal Anemone (Calliactis polypus), mostly associated with Hermit Crabs (see page 16) and Clownfish Anemone (Entacmea quadricolor), hosting the clownfish adults. Photo: J. Dafni, M. Levin

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Tube AnemonesCoral anemones are a unique division – order Ceriantharia - of sand-dwelling solitary corals with anemone-shaped, elongated bodies and pointed ‘sole’ to enable burrowing in the sand. The body is covered by a cylindrical sheath and is usually hidden in sandy or muddy substrate. Usually only the tentacles are visible above the ground. The mouth, placed on a central disk, is surrounded by two crowns of tentacles: short labial tentacles and longer marginal tentacles. The external ones, variously colored, capture the prey and pass it to the internal (oral) tentacles that pass it to the mouth.

Wrapper Sea-anemoneThese small Wrapper Sea-anemones, known also as Tiger anemones are always found enwrapped on branches of dead gorgonians or black corals. They are sometimes crowded on the gorgonian stalk to the point where no piece of the underlying coral skeleton is visible. Most of the anemones have uniform brown to orange color, while a few are whitish spotted with dark stripes. It is unknown whether they kill the coral or settle on the dead skeletons.

The Wrapper Anemone (Nemanthus annamensis) covering a dead sea whip and a fan coral showing both color patterns. Photo: I. Ben-Tov

Coral anemonesCorallimorpharia, or Disk anemones, are another group of sea anemone-like polyps with short ormissingtentacles,andaflattishappearance.Theirmusclesareweak,andtheycannotretractwhen threatened.

Corallimorpharian sea anemones: (right to left) unknown species; Actinodiscus nummiformis and Discosoma sp. Photo: J. Dafni

Ceriantharia: Tube Anemones (Cerianthus or Pachycerianthus sp.). The pictures were taken in the lagoon and in the sandflatsamongthereefknolls.Right,themembranoustubes,surroundedbyaschooloftinyMysid Shrimps (Idiomysis tsurnamali), planktonic crustaceans that seek shelter among their tentacles. Photo: M. Levin, B. Tamir

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Marine WormsThe term “worm” has been misused for many years as a common name for many kinds of animals, mostly drab and uninviting. Tropical marine worms, either Flatworms (phylum Platyhelminthes) or Bristleworms (phylum Annelida class Polychaeta) are diverse and beautiful, adorning the coral reef environment. The polychaete class is divided into two main groups – Errantia and Sedentaria. The errant worms are subterraneous, or hide inside reef crevices and seldom met by the casual diver, whereas the sedentary worms head carries long tentacles some of which convey to us their sheer beauty. They hide in soft organic or rigid calcareous tubes from which the tentacles emerge to catch plankton. Some species like the Eilat tubeworm, build a “reef” structure combining thousands of worm tubes into a magnificent flower-like bounty. Another highlight is the Christmas-tree worm.

Sedentary Polychaetes: Indian Tubeworm (Sabellastarte indica) and the variably colored Christmas-tree Worm (Spirobranchus giganteus). Photo: J. Dafni

Flat Worms and Tube-dwelling WormsOne group of flatworms, thePolyclad Turbellaria, shows a high diversity of crawling and swimming beauties. Here are two chosen representatives.

More Sedentary polychaetes: The “reef-forming” of Eilat Tubeworm (Filogranella elatensis),firstlydescribedinEilat,commontomanyIndo-Pacificlocalities;thesame,atcloserlook.Anotherreeftubeworm, Striped Tubeworm (Sabellastarte cf. sanctijosephi.) and an unknown Sabellid (Sabella sp.). All radiate exquisite beauty. Photo: M. Levin, A. Colorni, J. Dafni

An undetermined errant worm, found among coral debris in the lagoon. Photo: J. Dafni

Two worms, two life modes: swimming, Pseudobioceros sp. and crawling worm Pseudoceros. Colors are used for either for disguise or as warning coloration to deter predators. Photo: M. Levin

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Mollusca: GastropodaGastropods (snails) are the largest class in the phylum Mollusca, which includes three other common classes – Polyplacophora (chitons, see page 10), Bivalvia (clams) and Cephalopoda (squid and octopus) – well-represented in Eilat’s reefs. Over 800 gastropod species live here in a variety of habitats, from the intertidal to the deeper water. The gastropod shell is usually an externalspiralorcoiledshell,fromwhichthesnailbodyemergesandcrawlsonaflat“foot”.Theshell is formed by calcium carbonate secreting glands in the mantle, adorned by color pigments thatproducetypicalspecies-specificpatterns.Commonlythewordsnail is restricted only to those species which have an external shell. Those without a shell or with only a very reduced or internal shell are termed slugs. Primitive gastropods, such as limpets, Top shells and Conchs are herbivores, scraping algae from the rock, whereas more advances species, like Frog shells, Helmet shells and Cones are carnivores. Cowries havemixeddiets.Somepredatory snails specializeoncoralflesh (page157).The mollusk shells are no less beautiful than the living animal. Yet the sea slugs, shell-less crawling and swimming gastropods, are splendid, showing astonishing colors and patterns (pages 80-81), which apparently serve as warning coloration to notify predators that they are distasteful or poisonous.

Turban Snail (Turbo radiatus) equipped with a calcareous operculum known as ‘cat’s eye’. Frog Snail (Tutufa rubeta), with a horny operculum, and a Top Shell (Trochus dentatus). Photo: J. Dafni

Samples of Gastropod diversityThe Spider conch uses its operculum as weapon. It is sharp, claw-like and the animal pushes it against intruders as well as using it to turn itself upside down. The cowry shell is always kept shining because it is completely enveloped by the two-fold mantle that covers it constantly with fresh enamel layers. The Striped engina is a modest small snail, one of many inhabiting the lower intertidal zone.

Spider Conch (Lambis truncata sebae) a vegetarian, and the Arabian Cowry (Mauritia arabica immanis) a scavenger – both are endemic Red Sea species, whereas Striped Engina (Engina mendicaria) is common throughout the entire Indo-Pacific.Photo:J.Dafni.

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“Spider” strategy in Worm snailsBelow, a unique group of specialized snails of the family Vermetidae is shown. Their calcareous tubes are permanently attached to the rock or merge into massive coral colonies. Their mode of feeding is similar to that of spiders. They produce silk-like mucous strands, and spread them in the vicinity of their tube aperture. Tiny plankton is entangled in the web. Every now and then the web is drawn in and the planktonic organisms and organic debris are ingested.

Cluster of Large Tube Snails (Dendropoma maxima) totally covered by the mucous web and an Opercleless Tube Snail (Serpulorbis inopertus) (inset), with an emitted mucus strand. Photo: J. Dafni

Snail Reproductive behaviorSnails reproduce internally – males and females meet and copulate. The eggs are liberated in eggstrands,orinavarietyofcapsules,toprotecttheeggsfrombeingeatenbyfishandotherbrowsers. Sand-dwelling snails produce a unique protecting device – a ‘sand collar’ - in which the entire egg mass is mixed with sand grains and glued together with mucous.

A whelk (Nassa situla) female, and two Spindle Snails (Fusinus polygonoides) laying their egg in leathery. Moon Snail (Polinices mammilla) egg mass inside a “sand collar” (inset: bare shell) Photo: J. Dafni, M. Levin

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Opisthobranch snails - SlugsIn this subclass of Gastropods there is a tendency to lose the shell and adopt a bilateral symmetry, which shows best in the order Nudibranchia.Astheirscientificnameimpliestheseopisthobranchsreplaced the fore gills (prosobranchs)with a ‘bouquet’ ofmodified gills around the anus.Tocompensate for the loss of the protective shell they are equipped with a poisonous mucous coating and vivid color patterns to advertise their being unpalatable. Some carnivorous slugs, of the sub-order Aeolidina, prey on hydrozoans and store their cnidocytes secondarily in special club-like cnidosacs, in order to use them to defend themselves against predators.

Spanish DancerSpanish dancer Spanish dancer is the largest (up to 40 cm) nudibranch gastropod. It is known for its swimming behavior, gracefully flapping itsmantle edges – in amanner similar to thedressliftingofSpanishflamencodancers.Theblood-redcolorationisoftenadornedwithawhitemargin to their mantle, and is considered a warning pattern, indicating to its enemies of having poisonous substances obtained from their food – sponges. They are hermaphroditic, and deposit their eggs within a gelatinous spiral strand.

Spanish Dancer, or “bloody six-gills” (Hexabranchus sanguineus)exhibitedhere,showsin thefrontare twomodifiedtentacles (rhinophores),twooralflaps,andontherear-aclusterofsixbranchedgills.Spiraleggstrand(inset).Photo:Y.Aharoni, A. Gur

Several nudibranchs, the most advanced opisthobranchs: Shield Slug (Phyllidia undula), the Aeolid Favorinus tsuruganus, and the Doriids, Ceratosoma magnificum, and Hypselodoris infucata. Photo: J. Dafni

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Mollusca: BivalviaBivalves are mollusks of the class Bivalvia. As their name implies, their shell consists of two valves or half-shells, hinged by an elastic ligament. Usually the two valves are similar and equal in size, but in some forms such as the oysters they attach to the substratum by one valve. Muscles run between the inner surfaces of the valves, enabling the shell to close rapidly and tightly. The mantle cavity hides the hatchet-like foot, used for burrowing in free-living species. Burrowing bivalves have two siphons, long or shorter tubes extending from the rear end, one for intake of oxygenatedwaterandfood,andanothersiphonfortheoutflowofwastes.Thegills,withinthemantlecavity,functioninfilter-feedingaswellasinrespiration.Aswaterpassesoverthegills,tiny organic particles are strained out and carried to the mouth. Some bivalves attach themselves to surfaces by means of organic threads (called byssus), or by cementation. There are over 200 speciesofbivalvesintheGulf,amongwhichyouwillfindscallops, clams, oysters and mussels. Since the head is hidden, most bivalves have lost their eyes. Only a few, like the Coral clam shown here, have developed secondary eyes along the mantle edge.

Three bivalves: Coral Burying Clam (Pedum spondyloideum), displaying many eyes at the mantle’s margin, Sand buried Sand Pen Shell (Pinna muricata) and Egyptian Pearl Oyster (Pteria aegyptiaca). Photo: J. Dafni

Giant clams, Tridacna maxima (above) and T. squamosa (center) are both symbiotic bivalves, harboring zooxanthellae that provide the clams with their produced food, mainly sugars. A 40 cm

large clam is probably more than 20 years old. Protecting them from collectors and fishermen ensures their survival in theEilat Coral Nature Reserve. Below Right: a Swimming clam (Lima sp.). Photo: J. Dafni, O. Lederman

Bivalvia: Giant clams

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Cephalopods: Cuttlefish and OctopusThe Cephalopods are the most advanced class of the phylum Mollusca, both in their swimming, crawling, “jet propulsion” and other behavioral aspects. They are characterized by bilateral symmetry, carrying a distinct head, and an attachedmollusk foot which has beenmodifiedinto 8-10 tentacles (hence the name cephalo=head, pod=foot).The class includes squids and cuttlefishwhichhaveaninternalskeletonintheshapeofaboatorflexiblerod,whereasmembersof the octopus class lack any kind of hard skeleton. Cephalopods are regarded as the most intelligent of the invertebrates and have well-developed senses. They have special skin cells calledchromatophoresthatchangecolorandareusedforcommunicationandcamouflage.Allcepahlopods spurt black ink to ward off predators and as “smoke screen”. Octopuses have 8 arms, whilecuttlefishandsquidhaveanextrapairoflongertentacles,withwhichtheygrasptheirprey,and a powerful sharp beak.

Cuttlefish (Sepia aculeata) female has its egg mass attached to the underside of stones. Squid (Sepiotheuthis sepioidea) sometimes swim in large schools. Photo: J. Dafni

Cephalopods: OctopusesThe octopus has no internal skeleton or outer shell, which enables it to squeeze through narrow spaces.Itisveryintelligent,andpreysuponfishandinvertebrates.Likeothercephalopods,theoctopus male uses one of its eight arms, called Hectocotylus, to transfer his spermatophores (sperm-containing capsules) into the female’s mantle cavity during copulation. Octopuses have a highly complex nervous system, only part of which is localized in its brain, and an outstanding learning capability. They often break out of their aquariums in search of food. Some octopuses, such as the Mimic octopus (next page), move their arms in ways, that emulate the shape and movements of other sea creatures. A unique open sea octopus is Paper nautilus, of which the femalesecretesaspecialthinexternalshellbythegreatlyextendedwebofonepairofmodifiedarms to contain itself and her hatched brood.

A pair of White Spotted Octopus (Octopus macropus) copulating, and (below) in food search. Note the different and variable coloration. Female of a Paper Nautilus (Argonauta argo), cradled in its egg case. Photo: A. Gur, J. Dafni, N. Shashar

male female

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Octopus : BehaviorOctopuses show a wide range of behavioral patterns: aggressive postures, changing their shape tomimicpatterns, aswell asmodesofmovement– suchas“jetting“or even imitatingotheranimals’ “walking” or “running”. Many of these behavioral patterns are unexplained. They use their environment to hide or ambush their prey. The octopus female displayed here usually enters empty bivalve shells to lay her eggs, but has been observed doing so in plastic cups.

Unidentified octopus in an aggressive or ‘intimidating’ posture. Shell inhabiting octopus (Octopus marginatus) shelteringin a bivalve shell, apparently to hatch its eggs. Photo: D. Weinberg, I. Ben-Tov

Mimic octopusThe exceptional mimic octopus uses its arms, in their many arrangements, to mimic the shapes ofseastars,seasnakesandevenfish(lionfishandflounders).ItwasdiscoveredinIndonesia,andhas been found lately in Eilat.

Mimic Octopus (Thaumoctopus mimicus) in its natural habitat, among sea grasses: towering over its burrow, peeping out from inside, imitating a sea-snake and a brittle-star. Photo: J. Dafni

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Crustaceans: Lobsters and prawnsLobsters, prawn and shrimps are grouped in the order Decapoda Macrura, “Ten-legged, long abdomen”, shown on this page, whereas the “short abdomen” Brachyura are shown on the opposite page. They are too many to count here and only a representative few will be discussed. The Clam-killer slipper lobster is a nocturnal predator of giant clams, and the Marble shrimp has excessively long chelipeds. Hermit crabs are an intermediate group, Anomura, of crustaceans which hide their long soft abdomen in a dead snail’s shell, carrying it along.

Macrura and Anomura: Clam-killer Slipper Lobster (Scyllarides tridacnophagus), Hermit Crab (Dardanus lagopodes) in an empty cone shell (Conus tessulatus); Marble Shrimp (Saron sp.) with long pincers. Photo: M. Levin, I. Ben-Tov, R. Biran

Crustaceans: Crab varietyThe Brachyura, the short-abdomen crabs are the most advanced order of the Decapoda. Their short abdomen folds against the head-chest (cephalothorax), being widest in females, to store their eggs in the space between them. The coral crabs(page31)residebetweenthecoralbranches,taking part in their defense. The Variable Coral crab strolls around the reef, feeding on anything that crosses its path. The Sponge Carrier crab uses corals, sponges or ascidians to hide and protect it from predators. In the coral gall crabs the female imprisons herself in a gall created by the branched coral. The dwarf male enters into this ‘cage’ to fertilize her, and she remains there to care for her offspring.

Decapoda Brachyura, Above: Variable Coral Crab (Carpilius convexus), largest brachyuran in Eilat’s reef, a male (the female color is uniform brown). Below right: coral Gall Crab (Hapalocarcinus marsupialis) gall and a female with big abdomen (inset), Carrier Crab (Dromia sp.), carrying a large sea squirt. Photo: B. Levi, J. Dafni, J. Poupin, D. Weinberg

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EchinodermsThe animals’ name, echinoderms, implies strangeness - “spiny-skinned”. Taxonomists grouped together several thousand animal species that sometimes differ from each other very much into the eccentric phylum Echinodermata. A deeper examination of their morphology and anatomy proves this to be the right decision. They share among them exclusive characteristics, shown by no other group. Their most distinctive trait is being exclusively marine – no echinoderm species ever ventured into inland waters or onto land. Moreover they are always considered – in history, art and lore – as symbols of the sea. The biology and physiology of echinoderms are also quite unique. Although they are invertebrates - lacking skeletal backbone - they show advanced anatomical peculiarities that group them in the Deuterostomia division, together with the better-known vertebrates. They show however many “primitive”phenomena:theirsymmetryisround,five-fold(pentaradial)andtheyhavenolegsor other locomotor appendages– yet they move around using tubefeet, long tiny pipes carrying an adhering disc, which are activated by a hydraulic mechanism termed water-vascular system, unique to echinoderms. They have no eyes, yet they show remarkable ability to tell light from dark, through light-sensitive pigments in their skin, and light plays an important role in the diel activity cycle of many echinoderms (e.g. feather-stars, sea-urchins, etc.). Their breeding is also different from any other animal group: they release eggs and sperm from a series of genital pores to produce swimming larvae. This reproductive behavior is ‘contagious’: once one animal has started, all sexually ripe individuals in the vicinity contribute their eggs andsperm.Thefertilizedeggdevelopsintoafloatinglarva(namedpluteus in sea-urchins and brittle-stars, or auricularia in sea stars and sea cucumbers) that spends some weeks or even monthsdriftingintheopenseabeforedescendingtotheseafloortosettledownanddevelopintoa crawling adult. Thefive classes differ inmany aspects.While sea urchins are mainly grazers, sea stars are predators, able to prey on animals of their size or even – if the prey is strongly attached to the bottom – envelope their prey with the frontal part of their stomach, smothering it and starting to digest it externally. Feather stars and basket starsfilter smallplanktonicorganisms fromthe current, and sea-cucumberseat...sand!Theymoveontheseafloor,ingestlargeamountsof sand, dig out the organic particles and excrete ‘sausages’ of cleaned sand. There are many morepeculiaritiesinthemorphology,anatomyandphysiologyoftheechinodermswhichjustifythe saying “strange is their middle name”. So strange that a famous American zoologist, Libby Henrietta Hyman, once wrote, that it seems that echinoderms were specially created in order to bafflethezoologist.

Five classes of echinoderms: Sea-cucumbers, Sea-urchins, Brittle-stars, Sea stars and Feather-stars. Photo: J. Dafni, M. Levin, A. Diamant

Echinoderm PredatorManyfishcravetheinternalorgansofspinyechinoderms.Thebest-knownaretheBlue triggerfish, shown here. It blows water and exposes the sea urchin, turning it over to reach the less protected part of its body. Large wrasses are known to prey on brittle stars; they even seize long-spines sea urchins by their spines, carry and smash them onto rocks.

The ultimate echinoderm predator Blue Triggerfish (Pseudobalistes fuscus), crushing a Sand Dollar (Clypeaster humilis). Inset: half-buried (arrow) and exposed sand dollar. Photo: M. Levin; J. Dafni

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Sea StarsDo not be misled by the innocent beauty of the sea stars of the class Asteroidea, or as many erroneouslycallthem,starfish.Theserenityofthisgeometricallyperfectcreaturehidesaviciouspredatorofmollusksandother livingcreatures.They typicallyhavefiveormorearmswhichradiate from an indistinct central disk. The mouth is in the lower center of the disk, but there is no anus.Seastarsdonotrelyonajointed,movableskeletonforsupportandmovement,butinsteadpossess a hydraulic system for locomotion, based upon tubefeet on the lower part of the sea star’s arms. The Sea stars usually hunt for shelled animals such as oysters and clams. They have two stomachs, a frontal cardiac and a posterior pyloric one. The last one is used for digestion, while the cardiac stomach can be extended out of their mouth or even everted to engulf the prey. This feature allows the sea star to hunt prey that is much larger than its mouth would allow. Sea stars are known for the ability to regrow lost or damaged arms. In some sea stars, an entire sea star may be regenerated from a single arm attached to a portion of the central disk.

Themostinfluentialtropicalseastar–withalongtermeffectonentirereefs–istheCrown-of-thorns sea star (COTS in short); referring to the crown of thorns that Jesus wore before his crucifixion.Havingmultiple (12-20) armsanda large size (up to40cm), this sea star iswellequipped with long venomous spines for protection. The COTS is a coral predator that preys upon coral colonies by climbing onto them, extruding its cardiac stomach over them, releasing digestive enzymes, and ingesting the decaying tissue. The COTS’s main enemy is the huge Triton trumpet snail (Charonia tritonis). The small Harlequin shrimps bite small pieces from the sea star, and may even kill it. Coral crabs (Trapezia spp.) are known to chase the COTS away from their host coral.

COTS populations strongly fluctuate, and since the 1970s large outbreaks of this specieshavecausedtheneardemiseofmanyIndo-Pacificcoralreefs.Theseoutbreaksarebelievedthatto be caused by over-collection of the sea star predator, the tritons, while others blame pollution-induced algal blooms that increased the survival of the COTS larvae. The Red Sea suffered several outbreaks. In the last one, in 1998, many thousands of Acanthaster sea stars were removed from Ras Mohammed Natural Park, Sinai. At Eilat they are relatively rare, but their population is monitored to avoid damage.

From the largest to the smallest: Pigmy sea star is ca. 1-2 cm large, and has usually more than5arms.Asthepictureoverleafshows,itistheresultofdeliberatefissionoftheseastarsandregeneration of new arms, a form of asexual reproduction. They live unnoticed on the reef wall, scavenging coral and small sea anemone polyps.

Crown-of-thorns Sea star (Acanthaster planci):juvenileandanadult,devouringabranchedcoral.Right:Seastarpredator,Harlequin Shrimp (Hymenocera elegans). Photo: J. Dafni, O. Lederman, A. Diamant

Sea Stars

Common local sea stars: Cushion Sea star (Choriaster granulatus); Pearl Sea star (Fromia monilis); Pigmy Sea star (Asterina burtoni) fissiparous half (arrows point at the newly regenerating arms), and Ghardaqa Sea star (F. ghardaqana). Photo: L. Dafni, M. Levin, J. Dafni, B. Tamir

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Sea UrchinsSea urchins (class Echinoidea) have a circular body, either globular (as in the subclass Regularia) ovateorextremelyflattened(asintheIrregularia). Their body is totally covered by an internal rigid shell (called test),madeofclose-fittingcalcareous plates, with two openings: for the mouth in the lower (adoral) side, and the anus in the upper (adapical) side. In the regular sea urchins, fiveradiimadeofsmallerplates,calledambulacra,stretchalongthelongitudinalaxis,markedbytiny holes in the test, through which the ambulacral tubefeet emerge. These tubefeet adhere to the hard substrate and are either used to anchor the urchin in position, move it and even turn around. The test carries many large primary spines and more slender secondary spines, which in many species encircle the primaries. Specialminute spines, equippedwith three armed jaws calledpedicellaria, may be mildly venomous. The sea urchin feeds with a specialized chewing device called “Aristotle’s lantern”madeoffivehardteeth,toscrapealgaefromtherockanderodethemineral rock into sand. Five sex pores encircle the anus, the gonopores, whence the sperm and eggsarereleased.Apopularoldjokeasks:“Howdoseaurchinsmate?”Theansweris“Very,very carefully, because of the spines”. In fact, the spines are the main obstacle which prevents us from totally engrossing ourselves in the beauty of the reef. The long and sharp spine ‘forest’ of the Long-spine urchinisahavenformanycreatures-fish,shrimps,prawns,smallcuttlefish,nocturnalfishwho seek shelter duringdaylight andmanymore.Paradoxically, another blackurchin species, Double-spined urchin, with blunt primary spines, is the most fearful urchin. The secondary spines hidden between its primary spines are needle-sharp and their sting causes acute pain.Theyareapparentlythemostefficientofthereefprotectors: theykeepawaymanyevil-doers.Anyway,ifyourintentionsaregood,justavoidtouchingthem! In contrast to the above mentioned species, most sea urchins in Eilat reefs are harmless. Even the poisonous Fire urchin is so rare that its menace can be easily overlooked. A toxic sea urchin of the tropical family Toxopneustidae is the Short-spined velvet sea urchin. It is the largest and oneofthemostvariablespecies.Thisspecieshasbeensubjecttobizarredeformationsduetoseapollution (page 158).

Irregular echinoids: Common Sand Dollar (Clypeaster humilis) half-buried in sand and another one, fully exposed; a Fissured Sand Dollar (Echinodiscus auritus). Bottom left: Spiny Heart Urchin (Lovenia elongata) ventral face and a Helmet Shell (Casmaria sp.) killing this urchin. Photo: J. Dafni, M. Levin

A gallery of regular Sea urchins: Ten-lined Urchin (Eucidaris metularia), Velvet Sea Urchin (Tripneustes gratilla elatensis); Double-Spined urchin (Echinothrix calamaris); Fire Urchin (Asthenosoma marisrubri), Geometric Urchin (Microcyphus rousseaui) and Slate Pencil Urchin (Heterocentrotus mammilatus). Photo: J. Dafni, M. Levin, I. Ben-Tov

M

Sea urchins: Regular or IrregularThe regular sea urchins are globular, and radially symmetrical. Sea urchins of the other group, the Irregularia, are bilaterally symmetrical and have a distinct length axis and orientation. They aredividedinto(1)theflattenedSand dollars (order Clypeasteroida), whose mouth is in the ventral (lower) middle of the skeleton, but the anus is far behind in the ventral side, and (2) the almost globular Heart urchins (order Spatangoida) whose mouth is in the frontal ventral side (M, in the picture below) and the anus is in the posterior edge. Since all the irregular sea urchins burrow in the sand, the tubefeet system is much reduced and used mainly as respiratory organ, inaflower-shapepetaloid. They use their spines as oars or paddles to move beneath the sand surface.Theurchinsoftheformergroupareflatandmoveslowlyatshallowdepth;itiseasytolocate them through their wide sand marks, whereas the heart urchins dig deeper and move faster, leaving no trace on the sand.

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Sea CucumbersSea cucumbers are echinoderms of the class Holothuroidea that have an elongated worm-like bodycoveredwiththickskin.Theycrawlontheseaflooringestingsand,digesttheorganicmatterand excrete their droppings as sausage-like sand strings. Their skeleton is reduced to typical imbedded calcite ossicles,whoseshapesarespecies-specific,bywhichthepreciseidentificationof sea cucumber species is made. Most common sea cucumbers of the order Aspidochirota (=shield-hand), are favored food in the FarEast, under the name“trepang”.Afish parasite,pearlfish (Carapus sp.) enters the cucumber through its anus, and feasts on its intestine. A probablemeansofprotectionagainstthispestarethefiveanal teeth that surround the anus of the sea cucumber Actinopyga (see opposite page).

Sea Cucumbers: Black Sea Cucumber (Holothuria atra),seafloorfeedingandwithexcretedsandstring;Tubercle Sea Cucumber (Stichopus sp.); Noble Sea Cucumber (Holothuria nobilis); Tigertail Sea Cucumber (H. hilla) and Edible Sea Cucumber (H. edulis). Photo: J. Dafni, M. Levin

Black Rope-Cucumber (Synapta reciprocans), Grey Rope Cucumber (Opheodesoma grisea), and Greenish Synapta, (Euapta godeffroyi). Photo: B. Tamir, M. Levin, J. Dafni

More on Sea Cucumbers

Behavior: When disturbed, the half-buried Sticky Sea Cucumber (Holothuria impatiens)ejectssticky threads called Cuvierian tubules, to deter and obstruct enemies. Left: Upright posture of the sea cucumber Actinopyga bannwarthi, shared by all ripe members in the area at reproduction, whentheysynchronicallyejecteggsandsemen.Asemenstringisshowninthefarrightcornerofthe picture. Fertilization takes place in the water. Photo: J. Dafni, K. Levy

The second order of cucumbers is Rope cucumbers, Apodida.These flexible, elongatedsnake-like creatures lack tubefeet, moving about by peristaltic contraction of their peripheral muscles, using their skin’s anchor-like ossicles to hold to the ground, gathering food with their long oral tentacles.

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Brittle StarsBrittle stars, class Ophiuroidea,arecloselyrelatedtoseastars.Theygenerallyhavefivelong,slender,whip-likearms.Unlikeseastars,theyusetheflexiblearms,consistedofvertebra-likecalcareousdisks,tocrawlorclingtosolidobjects,suchasspongesorcorals.Thetubefeet are used mainly to collect food and move it to the mouth, situated in the lower middle of the disk, and there is no anus. Reef inhabiting stars are small, and readily overlooked. They resist predation by self-amputation of arms, and their later regeneration.

Subtidal Brittle Star (Macrophiothrix hirsuta), Speckled Brittle Star (Ophiocoma valenciae) and Reef Brittle Star (Ophiothrix propinqua) associated with a large Tube Sponge (Callispongia sp.). Another bizarre ophiuroid is the Basket Star, shown in the opposite page. Photo: J. Dafni, M. Levin

Feather- and Basket StarsFeather stars represent the echinoderm class Crinoidea. They are nocturnal animals that spread their arms against the current to trap small planktonic organisms and carry them to the mouth in its center. During the day they hide in shaded crevices with folded arms. At late afternoon theyemerge,crawlupwardsandholdfasttothereeftopbytheshortflexiblefinger-likecirri, spreading their arms against the plankton-rich current. The Basket star is similar in its behavior, but belongs to the brittle stars (class Ophiuroidea – see opposite page). Although both have no eyes they are able to sense the light, and their diel activity is triggered by light or darkness.

Reef Feather Star (Lamprometra klunzingeri) with extended, or with folded arms. Below left: Juvenile Basket Star (Astroboa nuda) reposing among soft coral branches. Photo: I. Ben-Tov, M. Levin

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Sea SquirtsSea squirts or Ascidia are the most primitive group in the phylum Chordata, and at the same time they are included among the invertebrates. They possess a central nerve chord (notochord) at their larval ‘tadpole stage’, losing it later in life when they are developed into sac-like solitary sessile animals or complex colonies of the same, often mistaken for sponges. They extract their food from seawater, taken in through an oral siphon,flowingthroughmucus-coveredgillslitsinto a chamber called the atrium, and exiting through the atrial siphon. They are covered by a tough outer “tunic”, hence their alternative name Tunicata.

Above: A Solitary Sea Squirt showing its oral and atrial siphons. Below: Two color variations of compound or Social Ascidian (Botryllus eilatensis) showing many small oral openings and larger atrial siphons. Photo: J. Dafni

Tunicata: SalpsSalps are planktonic barrel-shaped tunicates, swimming by contraction, pumping water through their transparent gelatinous bodies. They strain the pumped water and feed on phytoplankton. Salps reproduce asexually, forming long living colony chains seen in the water column at Eilat.

Hemichordata: Acorn WormsHemichordata is a sub-phylum related to the chordata. The only representative of this group in our area is the Acorn worm. It lives buried deep in the sand, using its smooth proboscis and gill slits to sieve organic particles from the wet sediments in which it is embedded. The acorn worm is very seldom seen on the surface. More commonly found are its excreted sand strings emerging from below, like toothpaste from its tube.

Giant Salp string (Salpa maxima), an infrequent visitor. Inset: a solitary salp invaded by a Pram Bug Amphipod (Phronima sp.). Photo: M. Shpigel. Y. Esh.

Acorn Worm (Ptychodera flava) sand paste emerging from the bottom. Photo: J. Dafni

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Reef FishOf all the creatures dwelling on coral reefs, none are more colorful and vivacious than the fishes.Thehighdiversityofthefishcommunitiesinthecoralreefsismaintainedmainlybythereef’s complexity, which translates into many different types of foods, shelter, and motion and reproduction opportunities. Of the more than 1200 species living in the Red Sea, approximately half have been recorded at Eilat, most of them in the reef environment. Below we will show the most common, interesting or exceptional species. Contrary to the invertebrate planktonic drifters, fisharetermednekton, meaning “swimmers.

Thehighreeffishdiversityiswellillustratedintheabovepicture.Sixfisheseachofadifferentspeciesaregatheredinoneframe: Broomtail Wrasse, Klunzinger’s Wrasse, Parrotfish, Snake Eel and a Speckled Sand Perch showing interest in a Blue Triggerfish (Pseudobalistes fuscus) burrowing in the sand for sea urchins. Photo: M. Levin

Reef Fish

Itishardtoimagineacoralreefwithoutthecolorfulandlivelycoralfishes.Withoutthemthisseascapewouldhavebeendullanduninviting.Twomainfishfamiliesareshowninthesepictures,theGroupers (Serranidae) and the Damselfishes (Pomacentridae). We will address them in more detail in the coming pages. Photo: M. Levin

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SharksSharksarefishofthesubclassElasmobranchii, with a cartilaginous skeleton and a typically streamlined body. They extract oxygen from seawater as it passes over their gills, exiting through fivegillslits.Theshark’sbodyiscoveredbysmalldermaldenticlesthatarealsousedasreplaceablelarger teeth. Unfortunately, reef sharks are entirely missing from Eilat - they obviously lost in the competition with man. Yet several sharks are met occasionally: in deeper water the small Hound Shark (Iago omanensis) is rather common. In shallow water Whale Sharks–thelargestfishonearth - visit the shore once or twice a year. This shark feeds on small plankton oraganism like the crustacean Krill, the favorite food of baleen whales, which are abundant in temperate seas, and infrequently become stranded on the beach.

Recent shark encounters (Above): Two photographs of a welcomed Whale Shark (Rhincodon typus), photographed whileswimmingalongtheshoreinthesummerof2005.Belowrighttoleft:anunidentifiedMako Shark (Isurus sp.), an infrequentvisitor,attractedtothefishcagesnearEilatnorthernshoreandKrill (Euphasia sp.) Photo: J. Grinfeld, A. Kendler, M. Levin, J. Dafni

Batoidea- Skates and RaysSkates and rays are also of the Elasmobranchia. Their pectoralfinsmergewith theirheads,formingfrontallylargedisc-likebodies.Thefrontalpartisflattofacilitaterestingandpreyingonthe sea bottom, while the posterior part is reduced, in some cases ending with a long thread-like tail. Unlike the sharks (order Selachii) having lateral gill slits,fishoftheorderBatoidea always havetheirgillslitsintheventral(lower)surfaceoftheflatbody.

The common reef Sting Ray (Taeniura lymma) usually rests in the lagoon, occasionally half-buried in the sand. The Electric Ray (Torpedo sinuspersici) uses its electric organs to stun and hunt its prey, and as a weapon. Photo: J. Dafni, M. Levin

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Batoidea- Skates and raysAmong the largest rays there is an evolutionary tendency to return to swim in midwater, shown by Eagle rays. Their pectoralfinsarepointedsideways,andtheeagleraysusetheminawaysimilarto birds’ wings. A step forward was made by Manta rays who adopted midwater swimming and plankton feeding similar to the whale shark.

Eagle Ray (Aetobatus narinari), agood swimmerhunts animalsburied in the sand, suchashidingfish, alsousinganelectro-sensory mechanism; and Manta Rays (Manta birostris), a midwater plankton feeder. Below: Oral lobes of the Manta Ray. The picture shows also several Suckerfish (Echeneis naucrates) hitching a ride close to the manta ray’s ventral surface. Photo: B. Tamir, I. Ben-Tov

Fish as PredatorsMostofthefishesarepredators,andonlyasmallpercentageeatsplants.Avegetariandietrequiresanatomical adaptations such as longer intestines, specialized teeth, and in many cases symbiotic bacteriainthegut.Noneofthesharks,themostprimitivefish,areherbivorous.Formostfish,predation is the rule. Large-prey predators hunt either singly, ambushing their prey, or in schools. Some,likelionfishandgroupers,swimamongtheirprey,waitingforanopportunitytopickoffsickorweakfish.

Two predators, two tactics: Above, Common Lizardfish (Synodus variegatus) ambushes passing fish. Below: PigmySweepers (Parapriacanthus guentheri) keep a safe distance from a Redmouth Grouper (Aethaloperca rogaa) that swims among them. Photo: I. Ben-Tov, J. Dafni

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Eels and Moray eelsThe eels (order Anguilliformes) have many representatives in tropical waters. The most common are Moray eels (family Muraenidae). They are large, multi-colored and resourceful nocturnal predators, hiding daily in crevices or meandering between the corals. Other eels are the subterranean Snake eels, and last but not least, the Garden eels, plankton feeders that live in permanent holes in large colonies, forming a spectacular attraction in Eilat’s seaward shallow seafloor.

Common reef moray eels: Snowflake Moray (Echidna nebulosa), Grey Moray (Siderea grisea), Yellowmargin Moray (Gymnothorax flavimarginatus) and Zebra Moray (Gymnomuraena zebra). (Another moray species is shown on page 115). Photo: Y. Aharoni, J. Dafni, M. Levin, E. Halevy

Sand Dwelling EelsAdapted to subterranean life, the Snake eels (Ophichtidae) have a narrow body and pointed head. The common Marbled snake eel is known to divers by its head popping out of the sand. When moving it leaves a zigzag pattern in the sand. No less unique are the Garden eels of the familiy Congridae, hundreds of which live in three large colonies, each burrowed in permanent holes in the sand, at a depth of 7-15 m off the southern beach of Eilat. They stay in their individual burrows, catching passing plankton. Potential mates stretch over from adjacent burrows andentwine their bodies.

Spotted Snake Eel (Myrichthys maculosus), mimicking the pattern of venomous sea snakes (common in the Indian Ocean but luckily entirely missing from the Red Sea); Marbled Snake Eel (Callechelys marmorata) in a typical head-out posture and an exposed animal, possibly in stress. Below: Garden Eels (Gorgasia sillneri) in their colony, forming a unique habitat, known as “Eel Garden”. Photo: Z. Movshowits, M. Levin, J. Dafni

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Sea horses and ShrimpfishesIn the order Syngnathiformesareincludedsomeofthemostbizarrefish-species–Seahorses, Pipefishes, Ghost- and Cornetfishes.Theirscientificnamereferstothetypicallong,tube-likesnout,madeoffusedjaws.Anotherpeculiarity:infishofthefamilySyngnathidae males have a brood pouch in which the female deposits the eggs; the males fertilize and incubate them.

Shrimpfish (Aeoliscus punctulatus), moving and hiding among sea urchins spines; Common Pipefish (Corythoichthys shultzi) group on a Favia coral, and a solitary Thorny Seahorse (Hippocampus histrix). Photo: J. Dafni, M. Levin, Y. Aharoni

Pipefish and Ghost pipefishPipefishes are relatives of the seahorse. They share their male brooding habit. Ghost pipefishes aredifferent;theyareperfectlycamouflagedandblendinamongalgaeorseagrassforprotection.The exquisitely colored Coral Ghostfishfitsthecolorofsoftcorals.Contrarytomostpipefish,theghostpipefishfemalecarrieshereggsinamodifiedbroodingpouch,madeof itsenlargedpelvicfins.Allareplanktonfeeders.

Pipefish:Multibar Pipefish (Dunkerocampus multiannulatus), middle row, pair of Coral Ghostfishes (Solenostomus paradoxus), the larger female shows its brooding pouch, and below, two color varieties of the Seagrass Ghostfish (Solenostomus cyanopterus). Photo: Y. Aharoni, M. Levin, B. Tamir

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Dragon fishSurprisingly, this strange creature is rather common inEilat’s lagoons.Their scientific name,Pegasus reminds us of the mythological winged horse that the Greek hero Perseus rode to rescue Andromeda, chained to the rocks of Jaffa, from a terrible sea monster. The dragon-shaped fish,completelyencasedintoughbonyplates, isotherwisevulnerable,anditseemsasif theywerenamedsoasajoke.Thealternativename,Seamoth,maybetterdescribethem.Thesefishtranslucent ‘winged’ pectoral finsareunfitforswimmingorgliding,ratherforcrawlingslowlyon the coarse sand in pairs, using their pelvic fin rays as digits. They have no swim bladder and barely swim. The thick skin protects them from predation, while they feed on small organic debris, with their tiny mouth, hidden beneath an elongated snout.

Dragonfish (Eurypegasus draconis)pairandafrontallookatthefish.Photo:M.Levin,J.Dafni

Lionfish and preyUnlikeothermembersof thevenomous scorpionfish familyScorpaenidae, Lionfish are not camouflaged(claimshavebeenraisedthatintheirnormalhuntingbehaviortheyimitatefeatherstarsorotherinnocentcreaturesornon-livingobjects),andslowlypatrolthereefedge,stalkingtheirfishprey.Theyareactiveintheearlymorningsandlateafternoons,sometimesinhuntinggroups not unlike a lion pack.

Lionfish (Pterois miles) keeping watch over Basslets (Pseudanthias squamipinnis).Below:Anunexplained‘flag’-ararecoloredheadtentacle–frequentlyseeninlocallionfish.Photo:M.Levin,B.Tamir

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Scorpion fish and Stone fishInthenexttwopages,othermembersofthescorpionfishfamily,subfamiliesofscorpionfishes and stonefishes are discussed. They are armed with highly venomous dorsal spines to discourage biggerfishwhomight attack themwhile they lie inwait for prey.Particularlyvenomous arestonefish,whicharesoperfectlycamouflagedthateventhebreathing‘pumping’movementofthe gill covers and mouth is obscured. The Devil scorpionfish, when threatened, upturns its lower side of its pectoralfins,exposingfora‘blinkofaneye’thebrightcolorsofthelowersurface,asa startling warning to its potential enemy.

Shortfin Lionfish (Dendrochirus brachypterus) and Clearfin Lionfish (Pterois radiata) challenge their enemies with their flamboyantredcolor;Devil Scorpionfish (Scorpaenopsis diabolus),camouflaged,andshowingitswarningcolors(inset).Photo: J. Dafni

StonefishThe Stonefishisacarnivorousfisharmedwith13venomousdorsal spines. It usually rests on the ground, perfectly blending with its surrounding, to ambush its prey. When threatened it spreads its fins,exposingitsspines.Itsrelation,thestingfish lives on lagunar sand, moving along using its pectoralraysas“fingers”.Toadvertiseitsvenom,thestingfishflarestheundersideofitspectoralfins,andspreadsitstailflashshowingadefiantexquisitewarning coloration.

Twomembersofthestonefishsubfamily(Synanceinae)ofthescorpionfish:theperfectlycamouflagedStonefish (Synanceia verrucosa), and the Two-Stick Stingfish (Inimicus filamentosus) in warning display. Photo: K. Levy, J. Dafni

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GroupersGroupers have a large head and heavy body, and spiny dorsal fins. Some grouper species rank among the largest top predators (except sharks) of the reef environment. They relate to the Serranidae, the largest family in the order Perciformes. At least 20 species of groupers are present in the Red Sea, most of them encountered in Eilat’s reefs. The most common and the smallest among them is the Blacktip grouper, and the largest – which lives long enough to reach the size of 80 cm – is the Lunartail grouper. Somewhat smaller are the Coral groupers. They werehuntedbyspearfishermeninthepast,andsincetheirsizeisage-dependent,theiraveragesize decreased. Protection measures taken at present have started to affect their numbers and increase their size.

Four typical Eilati groupers: Blacktip Grouper (Epinephelus fasciatus), Lunartail Grouper (Variola louti), Coral Grouper (Cephalopholis miniatus) and Red Sea Roving Grouper (Plectropomus pessuliferus marisrubri). An additional grouper – Redmouth Grouper (Aethaloperca rogaa) - is shown on page 107. Photo: J. Dafni, M. Levin

Basslets or GoldiesThereisnoquestionwhichisthemostphotogenicfishinthereefsofEilat.ItistheFairy basslet, known also as Goldy,apinkororangefish;noreefphotographwillbeperfectwithoutitsorangetinge. Basslets comprise the subfamily Anthiinae of the grouper family Serranidae. These agile plankton feeders swarm around every coral knoll or reef front, always facing the incoming current. Basslets are protogynous hermaphrodites, meaning that they are born females, to live in “harems” of up to a dozen females for the most productive part of their life, always surrounded by fewer dominant males. The territorial males perform an acrobatic U-swim (dive and rise) display and vigorously defend the water section they consider their ‘plot’. Non-territorial males join a “bachelors’” school, ready to take over if a dominantmale perishes.Alternatively, analpha female will change its sex to become a dominant male. At depths greater than 20m another species, the striped basslets, is common.

Above: A school of orange colored Fairy Basslets (Pseudanthias squamipinnis): females and several violet-pink males shown in the lower half. Below, male (right) and a female. Striped Basslets (P. taeniatus), males in deeper water. Photo: J. Dafni, M. Levin, R. Koslawsky

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ButterflyfishesButterflyfishes are conspicuous tropical reef fish of the family Chaetodontidae. About 15 species live in the northern Gulf of Aqaba. They are named for their brightly colored and striking patterns in shades of black, yellow, red and orange. Their deep, laterally compressed bodies are eye-catching in the reef background. Since they have no weapon for self-defense, they rely on deception to ward off enemies. Most species have dark bands or patch across their eyes, and some have bogus eyespotsontheirflanks,todeceiveorintimidatepredators.Butterflyfishesfeedoncoralpolyps.Theyareterritorial,swimminginpairsalongthereefflats.Bynighttheyhideamongst the crevices of the reef and some exhibit markedly different night coloration pattern. Below and overleaf are 8 common local species:

The animals went in, two by two…Butterflyfishes have brought pair bonding almost to perfection. They most frequently move together, male and female. Even within a school, pairs are very often visible.

Butterflyfish pairs: Crown Butterflyfish (Chaetodon paucifasciata), Threadfin Butterflyfish (C. auriga), Exquisite Butterflyfish (C. austriacus), a school of Bannerfishes (Heniochus diphreutes) and Lined Butterflyfish (C. lineolatus). Photo: J. Dafni, M. Levin

Six common Butterflyfishes from Eilat:Crown Butterflyfish (Chaetodon paucifasciata), Threadfin Butterflyfish (C. auriga), Masked Butterflyfish (C. semilarvatus), Striped Butterflyfish (C. fasciatus), Lined Butterflyfish (C. lineolatus) and Chevron Butterflyfish (C. trifascialis). Photo: J. Dafni, M. Levin

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AngelfishesMarine angelfishes, of the family Pomacanthidae,arerelatedtothebutterflyfishes.InHebrewthey are calledEmperors, and indeed, they are large, colorful andmajestic.Theydiffer frombutterflyfish by having a color-enhanced sharp spine for protection emerging behind the gill covers (hence their scientific name “mouth-spined”).Their poster-colored compressed bodiespossibly provide a territorial declaration. Their aggressive behavior is apparently the reason why thecolorsofangelfishjuvenilesoftendiffermarkedlyfromtheadults,possiblyaimedtoavoidbeingattackedbythem.Angelfishesareneverabundant;onlythesmallestspeciesgoinpairs.Yellowbar angelfish is the largest. Emperor angelfishesandRoyalangelfishes,althoughsmaller,exhibit more vibrant coloration.

Yellowbar Angelfish (Pomacanthus maculosus), adult and juvenile(inset).Photo:M.Levin

more Angelfishes

Royal Angelfish (Pygoplites diacanthus); Yellow-ear Angelfish (Holacanthus xanthotis) and below, Emperor Angelfish (Pomacanthus imperator)adultandjuvenile(inset).Photo:M.Levin,J.Dafni,A.Diamant

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Damsel fishDamselfishes, members of the family Pomacentridae,areamongthemostcommonsmallerfish species associated with coral reefs. They form territorial schools or associations - dominated by a male or in some cases by a dominant female. During the day they venture out to open water, feeding on zooplankton, hurrying back in case of emergency or during the night to hide among the coral branches. In the mating season, males adopt conspicuous ‘poster coloration’, choosing a smaller or larger rock plot whereto the females are invited to lay their eggs, upon which the malesejecttheirsemen.Themalesthenprotecttheeggsuntiltheyhatchandthetinyfingerlingsarecarriedawaybythecurrentstofindanewhome.Damselfishesareprotogynous sequential hermaphrodites(femalefirst)sexchange.Othersliketheclownfishshowprotandrous (male-first)sexchange.

Typicaldamselfishes:Sergeant Majors (Abudefduf saxatilis and A. sexfasciatus, behind), Banded Dascyllus (Dascyllus aruanus), Domino Dascyllus (D. trimaculatus) pair (mating male is grey), Green Chromis (Chromis viridis) (male), Sulphur Damselfish (Pomacentrus sulfureus), Royal Damselfish (Paraglyphidodon melas),acoloredjuvenile(adultispitch black) and Footballer Damselfish (Chrysoptera annulata). Photo: J. Dafni, M. Levin

Damselfishes in actionDamselfishesareterritorialfish,alwaysattachedtoananemoneorabranchingcoral.Theyseeksheltertherewhenalarmed.Ithasbeenfoundthatbywrigglingtheirfinsandtailsatnightthedamselfishesaeratethespacebetweenthecoralbranches,improvingthecoralmetabolism.Mostdamselfishusethecoralenvironmentaspreferredbreedingsites.

Damselfish interactions:Clownfish (Amphiprion bicinctus) symbiotic with a Cushion Anemone (Stoichactis gigas), Green Chromis (Chromis viridis)andbluejuveniles(inset),surroundingtheirhomebase,aStaghorncoral.The Banded Dascyllus (Dascyllus aruanus) shelters in a Stylophoracolony,frequentlytogetherwithotherdamselfish.Photo:M.Levin,J. Dafni

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WrassesCoralfishof the familyLabridae (=lipfish), are among themost abundant and conspicuousfishes in tropical reefs around theworld. There are approximately 50 species in theGulf ofAqaba. They appear in a diverse range of colors, shapes and sizes, often varying considerably according to their age and the available food. Wrasses feed on a large variety of invertebrates, and zooplankton. Some wrasses have protractile mouths, pointed snout to collect worms, or thick lipsandcanineteethtocrushmolluskshellsandseaurchinskeletons.Somewrassesfillausefulroleinthecoralfishcommunityascleaners.Fewwrassesaresexuallydimorphic,organizedintoharem-based social systems and exhibit protogynous sex change. Juveniles are often different from their parents.

Common wrasses: Klunzinger’s Wrasse (Thalassoma klunzingeri), Thicklip Wrasse (Hemigymnus fasciatus), Bird Wrasse (Gomphosus coeruleus), male (female see in page 181), Yellowtail Wrasse (Anampses meleagrides), Spottail Wrasse (Coris caudimacula), Clown Wrasse (Coris aygula) adult and juvenile, Eightline Wrasse (Parachelilinus octotaenia) and Hog Wrasse (Bodianus anthoides). Photo: J. Dafni, R. Koslawsky, Z. Movshowits, M. Levin

Wrasses in actionThe Broomtail wrasse is the largest wrasse in Eilat’s coral reef. The mature males reach 50 cm and show a long and tattered tail. A small vertical orange half moon-shaped mark, displayed at all ages,isahelpfulidentificationaid,reflectedinitsscientificname.Thiswrassefeedsonspinyseaurchins, among other prey, smashing their hard shells on the reef wall.

Broomtail Wrasse (Cheilinus lunulatus), attended by two Cleaner Wrasses (Labroides dimidiatus) (see next page). Right Inset:juvenileBroomtail Wrasse. Left inset: Broomtail Wrasse wounded by Long Spine urchin spines. Photo: J. Dafni, Y. Aharoni.

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Cleaning stationsA cleaning station is a location in the reef vicinity where fish congregate to be cleaned bycleaner-fishorshrimps.Thecleanersremoveparasitesanddeadskinfromtheir‘clients’bodies.The principal cleaner is the cleaner wrasse, which has developed a special behavioral pattern to advertise its services: it swims in a kind of wavy ‘dance’, pursuing and slightly touching approachingfish.Thefishestobecleanedshowtheirinterestbyposinginunconventionalways,even changing their color pattern – possibly to highlight the parasite or dead tissue – and opening their mouths and gill covers to facilitate the cleaner’s approach. The cleaner wrasse removes the parasitesdirectlyfromthecleanedfishskin.Cleaning stations are often located in cave entrances or on top of a coral head. The cleaner wrasse genus Labroides is the most specialized. All of its species are cleaners. But cleaning is also performed by other wrasses. Juveniles of the Fourline cleaner wrasse are similar in shape and behavior to those of the common cleaner, while the adult changes its feeding habits. An experiment done in the 1960’s showed that removal of the cleaner fishes froma coral reef resulted in a significant reduction infishnumbers andan increaseofdermalinfectionsintheremainingfishes.

Cleaner Wrasse (Labroides dimidiatus) with Damselfish (Dascyllus trimaculatus) and while cleaning a gaping Needlefish (Tylosurus sp.). Spottail wrasse (Coris caudimacula)wasalsoseenseveraltimesapproachingfishinasimilarway.Photo:I. Ben-tov, D. Weinberg, J. Dafni

Who else is in the Cleaners’ guild?Cleaner shrimps are long-tailed ‘swimming’ crustaceans (suborder Natantia) that also clean fishattheirowncleaningsites.Cave-dwellingfish,likemorayeelsandsmallerschoolingfishtoo small for cleaner wrasses, are attended by these shrimps. Several families have one or several memberswhodothisjob.ThemostcommoncleanershrimpisBanded boxer shrimp of the family Stenopodidae; another common cleaner is White banded cleaner shrimp of the Hyppolytidae. The smaller Squat cleaner shrimp cleans the sea anemone, to which it is commensal.

Variety of cleaners: Banded Boxer shrimp (Stenopus hispidus), and White Banded Cleaner Shrimp (Lysmata amboinensis), displaying their advertising white antennae, and while cleaning a Yellowmouthed Moray (Gymnothorax nudivomer) teeth. Partner Shrimps: Pereclimenes imperator keeps a sea cucumber’s skin clean and the transparent Pereclimenes longicarpus cleans a Lizardfish. The Squat Cleaner Shrimp (Thor amboinensis) is associated with sea anemone, removing organic debris from its surface. Photo: J. Dafni, M. Levin, A. Stern, I. Ben-tov, B. Tamir, E. Halevi

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Parrot FishThe Parrotfish (genus Scarus) is a notable example of specializationanddiversityamongreeffish.Itisnamedafterboth, its beaklike dental plates made of fused teeth and its brilliant coloration patterns. A special adaptation for scraping algae includes the stone-cutting beak and pharyngeal teeth, a grinding device inside the pharynx made of two bony toothed grinding plates which turn the calcareous pieces into chalky paste from which algal material is digested in its gut, exiting pure calcareous sand through the anus.

Heavybeak Parrotfish (Scarus gibbus), male. Photo: J. Dafni

Variations on a themeParrotfish are the main coral reef eroder. The fifteen parrotfish species in the Gulf exhibitbewildering color diversity because of their sexual dimorphism – females differ from males, and juvenileshavetheirowncolorationpatterns.Likemanycoralfishtheyexhibitprotogynous sex change.Theso-called‘terminalmales’showthemostintenseandvibrantcoloration.Parrotfishare mainly diurnal feeders. At night they seek shelter inside caves and crevices where they lay immobile, some even produce a transparent mucous ‘blanket’ to mask their scent from predators. The following showspictures of four of the commonparrotfish species -males, females andjuvenile-onEilat’sreefs.Allarecommonatthe“Caves”site,atadepthof1-5m.

CommonEilatParrotfishes, leftmalesand right, females, top tobottom:Dusky Parrotfish (Scarus niger), Heavybeak Parrotfish. (S. gibbus) Bullethead Parrotfish (S. sordidus) and Bicolor Parrotfish (S. bicolor), male, female and a juvenile(inset).Photo:J.Dafni

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GoatfishGoatfishesaretropicalfishofthefamilyMullidae.Theyextractfoodfromtheseafloor,usingapair of long barbels protruding from their chins to dig out worms and mollusks of the sand. The barbelsarealsochemosensoryorgans,abletolocateburiedfood.Severalfishspeciesaccompanythem, hoping to share in the booty.

Red Sea Goatfish (Parupeneus forsskali) searching for food, while a Spinecheek (Scolopsis ghanam) watches from above. Belowleft:asmallwrasseaccompaniesthegoatfishes,hopingtogetabite.Notethevarietyofcolors,displayedbyonespecies.Anothergoatfish(P. cyclostomus) is shown in page 181. Photo: J. Dafni

HawkfishHawkfishes,familyCirrhitidae,aresmallpredatoryfishes.Theyhavelargeheadswiththick,somewhatelongatedbodies.Theiranteriordorsalspineshaveseveraltrailingfringingfilaments- termed cirri-ontheirtips,hencethescientificfamilynamemeaning“fringefins“.ThePixy hawkfishisoneofthemostcolorfulfishinEilat’sreefs.AdistinguishedrelativeistheLongnose hawkfish, associated with large sea fans. (See also page 67).

Hawkfish.Above:twocolorformsoftheBlotched Hawkfish (Parachirrhites forsteri) on ambush. Middle: Pixy Hawkfish (Cirrhitichthys oxycephalus) and Longnose Hawkfish (Oxychirrites typus), below. Photo: M. Levin, B. Tamir, J. Dafni

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Flat fishFlatfisharedeformedfishes,whichunderwentanevolutionarymodificationtoswimsideways:during ontogeny (individual development) one eye migrates from the “blind side” around the head, the dorsal and anal fins elongated, and the anus, usually in the rear end of the body moved towardthehead,pushedforwardsbytheelongatinganalfin.Thus,anewsymmetryhasdeveloped- both eyes lie on one side of the head, and the entire body lies on one side. They are naturally camouflagedandoftenhideinthesand.ThecommonspeciesLeopard flounder has both eyes on the left side, whereas Moses sole has them on the right. The last species is known to emit a milky poisonous substance known to deter sharks.

Leopard Flounder (Bothus pantherinus) and Moses Sole (Pardachirus marmoratus). Note the opposite orientation – left in the former, right in the latter – and the lateral line seen along the middle of the former’s body. Photo: J. Dafni

Low-lying fishFish living on sand without shelter must adapt both in shape and coloration to the uniform environment.Thismayinvolveeitherbecomingextremelyflattened,orbybehavior.ThreetypesofflatfisharefoundinEilat:thecartilaginousskatesandrays(seepage105),andfishoftheFlathead family, such as the Crocodile fish,obtainthelowprofilebyflatteningtheirdorsoventral axis. The other type are the side-lying flounders (opposite page). Stonefish, Stargazers and Lizardfishadaptbyburrowinginthesand(page153).

Aboveandmiddleleft:asideandfrontalviewoftheflatheadedCrocodile Fish (Papilloculiceps longiceps), a large predator. Below: the Arabian Tongue Sole (Cynoglossus sinusarabici),aflatfish.Notethatboththeelongateddorsalandanalfinsthatreachthemouth,enablingthefishtoswimonitsside,andthelaterallineatitsmidst.Their‘blind’sidefacingtheseaflooriscolorless,andlacksalateralline.Middleright:thesamefish’twistedmouth.Photo:J.Dafni,M.Levin

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BlenniesBlennies – family Blennidae–aresmallfishwithelongatedandflexiblebodies.Apairofwhisker-like cirri often protrudes from their forehead. Most of them are benthic (bottom oriented), burrowing in the sand or dwelling inside empty shells of worms or tube-shaped mollusk shells. TheyaresuperficiallysimilartomembersoftheGobiidae. Due to the lack of swim bladders, they are not neutrally buoyant, and normally rest on the hard substratum, or in their hiding crevices. A specialized member of this family is the Sabretoothed blenny, which mimics the color pattern of acleanerfishandbitesoffpiecesofskinandscalesfromits“clients”.

Above: Lance Blenny (Aspidontus dussumieri),asolitaryfishthathidesinemptytubesnailshells(aboverightofpicture),venturing out to feed on algae and organic debris. Shortbodied Blenny (Exallias brevis) lives among Fire Coral (Millepora) plates; an innocent Mimic Blenny (Ecsenius gravieri) imitates another, bite-inflictingBlackline Blenny (Meiacanthus nigrolineatus) (not shown); and Rockskipper (Istiblennius edentulus). Photo: J. Dafni, I. Ben-Tov

More Blennies…

Red Sea Leaping Blenny (Alticus kirkii) is an amphibious fish, perches on rocks, stickingout of the sea, and feeds on benthic algae. In an emergency it leaps to other rocks so quickly that it barely dips in the water. It breathes both air and oxygen dissolved in water. Highfin Blenny (Petroscirtes mitratus) isasmallfishfoundnearseaweedcoveredpiersandfloatingobjects.Themale has a typical elevated frontal fin.Other blennies appearing in the reef areArabian Fangblenny (Petroscirtes ancylodon) and Sabretoothed Blenny (Plagiotremus rhinorhynchus),anaggressivefishwhichpestersandbitesdiversandshelters in tubesnail’sshells. Photo: J. Dafni, M. Levin

.…and Nocturnal PredatorsCardinalfish family Apogonidae, and Soldierfish (Holocentridae) are the main small and medium-sized nocturnal predators (see also page 142). During the day they congregate, and inhabit all the reef’s nooks and crannies.

The small Goldstriped Cardinalfish (Apogon cyanosoma) is nocturnal. Male of a Tiger Cardinalfish (Cheilodipterus sp.), mouth brooding the eggs laid by the female. Photo: J. Dafni, D. Weinberg

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GobiesGobies, family Gobiidae, are small bottom-adaptedfishes, able to use their fused pelvicfinsas disc-shaped suckers to adhere to the rocky substratum to resist waves. They form symbiotic relations with other organisms. The special relation between the goby and the Bulldozer shrimp was initially studied at Eilat. The shrimp, almost blind behind the sand it carries out of its burrow, depends on the goby to warn against danger, in which case they both rush into the burrow. The shrimp ‘keeps in touch’ with its “sentry” by constantly stroking it with its long antennae.

Above: two Shrimp gobies (Cryptocentrus steinitzi) are shown sharing a burrow with a Bulldozer shrimp (Alpheus djibutensis) for protection. Below: The Graceful goby (Lotilia graciliosa) hovers over its “partner” shrimp (Alpheus rubromaculatus). Photo: A. Stern, M. Levin

Gobies and other small fishesIn addition to the Gobiidae, many colorful small- andmedium-size fish of various families(Pseudochromidae, Grammistidae, Nemipteridae) preside over the Eilat underwater vista. Some are shown here.

Small and beautiful: Orchid Dottyback (Pseudochromis fridmani), colored a fluorescent lilac-violet, which inhabitscaves and shaded crevices,wasfirst discovered inEilat and named afterDavidFridman, thefirst curator of the “CoralWorld”Aquarium.Anothersmallfish,Citron Goby (Gobiodon citrinus) inhabits branched corals. Yellowface Soapfish (Diploprion drachi), Common Soapfish (Grammistes sexlineatus), Frontal view of a Comet Longfin (Calloplesiops altivelis)inatypical“frightposture”inwhichthefish’longtailmimicstheshapeofamorayeelpeepingoutfromitsshelter;a common Eyebar Goby (Gnatholepis anjerensis), Speckled Sandperch (Parapercis hexophthalma) which inhabits the sandy lagoon, and a Spinecheek (Scolopsis ghanam). Photo: M. Levin, J. Dafni, A. Diamant, B. Tamir

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SurgeonfishesThe family of surgeonfishes, Acanthuridae includes ten species in the Gulf of Aqaba, all herbivorous, grazing and browsing algae with their specialized teeth. Fish of this family are distinguished by a pair of erectable spines, sharp like a surgical lancet in the caudal peduncle, in some species it is highlighted by a striking warning color pattern. Brown surgeonfish schools roam the reef and lagoon, grazing the short algae. Sohal surgeonfish’ feeding tactics are different –itisasolitaryterritorialfish,violentlydefendingitsplot.Brownsurgeonfisharealsofamousfortheirreproductivebehavior,firstobservedinEilat.Atsunset,theygatherinlargeschools;whencegroupsofseveralmalesandfemalesrushtothesurface,simultaneouslyreleasingjetsofeggsandsperm into the open sea.

A school of Brown Surgeonfish (Acanthurus nigrofuscus), and a solitary Sohal Surgeonfish (A. sohal). Photo: M. Levin, J. Dafni

Surgeonfish and UnicornfishesUnicornfishesdifferfromsurgeonfishesintwoaspects:theyhavetwopairsoffixedbonytaperingplates instead of one pair of erectable spines, and a grotesque shorter or longer spike protruding from their foreheads. They are mainly browsers, feeding on leafy brown seaweeds. Some species turned to zooplankton feeding.

More surgeonfish, and unicornfish: Sailfin Tang (Zebrasoma desjardinii), adult and juvenile (inset), Blackbarred Surgeonfish (Acanthurus gahhm) and Yellowtail Tang (Zebrasoma xanthurus), Bluespine Unicornfish (Naso unicornis) and the spike-less Orangespine Unicornfish (N. lituratus). Photo: B. Tamir, J. Dafni, E. Halevi, M. Levin

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RabbitfishesRabbitfishes,ofthefamilySiganidae, are also herbivores, seen frequently in seaweed-covered shallow lagoons. The most common species, Rivulated rabbitfish and Squaretailed rabbitfish live in larger schools, whereas the exquisite Stellate rabbitfish are seen mainly in pairs traveling across the reef.Rabbitfishareknown for thepoisonous sharp spinesfixedat the endof theirpelvic fins, and a hidden frontal dorsal spine that,unlike inotherfish, ispointed forwards–inflictingapainfulstingwhencarelesslyhandled.Theyalsochangetheircolorpatternquicklytomatch the vegetation, an effective measure against predators.

Squaretail Rabbitfish (Siganus luridus)schoolandanindividual,bearingcamouflagecolors(inset),andapairofStellate Rabbitfish (S. stellatus). Photo: J. Dafni, B. Levi, M. Levin

Twobar Bream (Acanthopagrus bifasciatus) the common natural seabream in Eilat. Fugitive Gilthead Breams (Sparus auratus) from the fish farms off the northern shore are found throughout the entire area.Circular Spadefish (Platax orbicularis), known also as Batfish, infrequently appears in larger schools. Photo: J. Dafni, M. Levin

Sea Breams and SpadefishThe Seabream, family Sparidae, isaprizedediblefish.ThebeautifulTwobar bream is their only representative in Eilat’s reef environment. Other edible species of this family are less conspicuous, and found in too small quantities to sustain commercial fishing. Mariculture practicedfor20yearsinfloatingcagesoffthenorthernshoreofEilat,wascenteredmainlyonthe Gilthead bream,anintroducedMediterraneanfish,thatwentwildandspreadalsotothereefenvironment. The related Spadefish (orbatfish),of theEphippidae, is vertically exaggerated, andoftenmistakenasbutterflyfish.

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Nocturnal fishesWhen diving at night, the light torch reveals myriad of small plankton organisms, that rise to the surfaceatnight,butrelativelyfewfishpredatorstofeedonthem.Mostnocturnalfisharesmallsolitary plankton feeders as well as their medium size predators. During the day they assemble, seeking shelter in caves and crevices. Most of them have large eyes, adapted for night vision, andarered-coloredor translucent.Atnight,whenyoupointyourflashlightatacardinal fish (Apogonidae),apearlylusterisreflectedbacktoyouduetoalayeroflight-reflectingguanine crystals in its skin. Other nocturnal fish families are the Soldierfishes (Holocentridae) and Bigeyes (Priacanthidae) , most of which are red colored with patterns of white or dark lines and patches.

Nocturnal fishes. Cardinal fish: Black-ringed Cardinal (Apogon annularis) and Fiveline Cardinal (Cheilodipterus quinquelineatus) in a mixed school with Goldstriped Cardinalfish.Soldierfish:White-edged Soldierfish (Myripristis murdjan), Crown Squirrelfishes (Sargocentron diadema)schoolduringthedayandasolitaryfishatnight,hidingbeneatha massive coral with extended tentacles and lastly, the Bigeye (Priacanthus hamrur). Photo: J. Dafni, M. Levin

Keeping the bed warm…

Nocturnal (White-edged soldierfish) and diurnally-activefishes (Basslets)meet in the reef corner just before changingshifts. Photo: J. Dafni

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SweepersTwospeciesofsweepers,nocturnalplankton-feedingfishesofthefamilyPempheridae are met diurnally in Eilat reef knolls and caves, the larger Cave sweeper and the smaller Pigmy sweeper. Both form dense population: the former is yellow-green and iridescent, changes colors according totheanglefromwhichthefishisviewedwhereasthealmosttransparentlatterspeciesjustlyearned its popular nickname ‘glass fish’.

Above: The Cave Sweeper (Pempheris vanicolensis) is a nocturnal plankton-feeder, spending the daylight hours in large schools in large caves or crevices. Below: Dense schools of Pigmy Sweeper (Parapriacanthus guentheri). They inhabit Moses Rock,themostpopularcoralknollintheEilatNatureReserve(seealsopage173).Photo:J.Dafni,Y.Aharoni

Life in the CurrentAlthough the reef is economically self-sustained, there is an energy trade-off between the corals and the surrounding sea. The reef exports nutritious substances secreted by the corals onto the sea,whileaninfluxofplankton,nourishedbythiscontributionisharvestedbymanyfishandinvertebrates of the reef. Planktonic organisms are carried along by currents that brush the reef edge.Smallfish,livingatthereefedgeorinoffshorereefknollsventureouttowardstheincomingcurrent to feed. It is evident that without the plankton, the reef ecology would be less rich and diverse.Largerpredatorslurkinthebackground,eagertoenjoythisbounty.

Small reef fishes, Basslets (Pseudanthias squamipinnis), Green Chromis (Chromis viridis), Miry’s Damsel (Neopomacentrus miryae) face the incoming current. The normal current off Eilat’s shore moves in a southerly direction. Whenthecurrentsshiftaroundthefishesheadintheotherdirection.Below:AschoolofBicolor Puller (Chromis dimidiata) and a Striped Butterflyfish (Chaetodon fasciatus) Photo: M. Levin, J. Dafni

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TriggerfishesTriggerfishes (familyBalistidae)have round, laterallyflatbodies.Among theanteriordorsal finsthefrontalfinspinesareerectile:thefirstspinelocksitsposition,andthesecondunlocksit(hencethenametriggerfish).Thisandasimilarerectileventral spine prevent predators from swallowingthemorpullingthemoutofhidingcrevices.AtleastsixtriggerfishspeciesliveinEilat. Picasso fish is the most colorful, and the largest of its family is the Blue triggerfish. The latter is a main predator of sea urchins. A pointed mouth and very thick skin protect it from the stinging sea urchin’s spines.

Triggerfishvariety:Bluethroat Triggerfish (Sufflamen albicaudatus); Red Sea Picasso fish (Rhinecanthus assasi), Adult andjuvenile(inset);Yellowmargin triggerfish (Pseudobalistes flavimarginatus); and Blue triggerfish (P. fuscus), in the process of eating a long-spined sea urchin. (See also page 91). Photo: J. Dafni, M. Levin

FilefishesMembers of the family Monacanthidae are related to the Balistidae. Their ‘trigger’, i.e. the second dorsal spine, is short, internally hidden and activated by muscles, and only one erectile spine shows, hence the scientificname“one spined”.A large specieswithvivid colors is theScribbled leatherjacket. The Unicorn leatherjacketisararespecies,anditisthefirstrecordofthisfishinEilat.Honeycomb filefishisanattractivefilefishwithapaleorvividcolorpattern.

Scribbled Leatherjacket (Aluterus scriptus) in an upright position and swimming; Unicorn Leatherjacket (A. monoceros) and below: the Honeycomb Filefish (Cantherinus pardalis)intwocolorvariants,andthreeunidentifiedfilefish.Photo:Y.Aharoni, M. Levin, D. Weinberg

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TrunkfishesThe bodies of Ostracionidfisharesolid,encasedinatriangularorquadranglebonycarapace, formedbyfusionoftheplate-likescales.Onlythefinsandtailarefreetowaggle.Membersofthisfamily come in a variety of colors, and are notable for the hexagonal or “honeycomb” patterns in their skin and dermal outer skeletons. Two common Eilati species are the Cube trunkfish and Thornback trunkfish, the former common both on the coral reef and in sandy habitats, while thelatter–beingwellcamouflaged-mostlyroamsthelagoonflats.Inspringmanyminuteblackdottedyellow‘dicefish’areseenamongseaurchinspines.TheyarethejuvenileCubetrunkfish.A close relative, Blue-tail trunkfish is less common.

Thornback Trunkfish (Tetrosomus gibbosus) sub-adult, Cubefish (Ostracion cubicus),newlybornjuvenile(‘dicefish’), a sub-adult and adult, Bluetail Trunkfish (Ostracion cyanurus) sub-adult and adult. Photo: J. Dafni, M. Levin

Porcupine fishTetraodontiformes isa taxonomicaldivision,groupingmembersof threefamilies:Trunkfish, Pufferfish andPorcupinefish.The last two are known also asblowfish because they are able toinflatetheirbodiesbyswallowingwater forprotection,morethandoublingtheirsize.Theporcupinefish,Diodontidae further enhances this characteristic by being armed with short or long erectile spines covering their entire body.They are also equippedwith a beak-like jaw,obtainedby fusingall the teeth ineach jaw tosharpplates,which theyuse tocrushshellsofmollusksandseaurchin.Theirjawismadeoftwo‘teeth’(hencethescientificname,‘twoteeth’).LiketheotherfishesoftheorderTetraodontiformes,theirskinispoisonous,anotherprotectingmeasure.

TwoPorcupinefishes:Yellow spotted Burrfish (Cyclomycterus spilostylus),normalandinflatedstate(inset);Long-spine Porcupinefish (Diodon hystrix). Photo: J. Dafni, A. Colorni, B. Tamir

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PufferfishesAnotherfamilyofblowfish,closelyrelated to theporcupinefish, is theTetradontidae (=fourteeth). Similarly, they have their teeth fused into plates, although with a distinct line of division (which ‘doubles’ their number).Another difference: they lack the porcupinefish long spines.Instead, their almost sandpaper-like skin carries minute spines. They are even more poisonous than other relatives: their inner organs contain a deadly poison called Tetradotoxin which may cause death in very low concentrations.Nevertheless, in Japan these fishes are processed byexpert chefs and served in restaurants as a dish called Fugu, as kind of “Japanese roulette”.

TwoPufferfish:Masked Puffer (Arothron diadematus), and a Stellate Puffer (A. stellatus). Photo: J. Dafni, M. Levin

TobiesThese two Tobies are also Tetradontids, although they are smaller and their blowing capacity ismuchlesseffectivethanthatoftheirblowfishrelatives.Theyshareothercharacteristics,suchas a long snout and being poisonous. The third, named Red Sea Minipuffer, is a typical lagoon inhabitant.

Crowned Toby (Canthigaster coronata), Pearl Toby (C. margaritata) and Red Sea Minipuffer (Torquigener flavimaculosus). Photo: J. Dafni

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FrogfishesFrogfishes, family Antennariidae, are highly specialized benthic fishes. They have three extended dorsalfinspineson theirheads, the frontalofwhich ismodified intoafishing lurecarryingasmallworm-like‘bait’ toattractsmallfishprey.Theyarewellcamouflaged,colorschange, in adaptation to their background. They also show a unique ‘walking’ and ‘climbing’ motion,enabledbyelbow-likejointsintheirpectoral and ventralfins.

TwoofthemostcommonfrogfishesofEilat:Freckled Anglerfish (Antennarius coccineus); and below, the variable colored Spotfin Anglerfish (A. nummifer). Photo: M. Levin, Y. Aharoni

On the Sand and beneathLiving on sand means digging, and this is what razorfishes do best. Their laterally compressed foreheadenablesthemtopenetratethesandattheblinkofaneye.Hereonefollowsagoatfish.Below, a lizardfish digs in to ambush and catches a green damselfish that strayed from the reef.

A Razorfish (Xyrichthys pavo) joins aGoatfish (Parupeneus cf. heptataenia) digging out sand dwelling worms or crustaceans. Inset: a juvenileX. pavo; Lizardfish (Synodus variegatus) in ambush and in the process of swallowing a damselfish,Green Chromis (Chromis viridis) (see page 122). Photo: M. Levin, J. Dafni

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Sea TurtlesSea turtles, descendents of terrestrial reptiles who went to sea many millions of year ago, are the only strictly marine reptiles now alive. Nevertheless they maintain their link with the non-marine environment in two ways: they breathe air and the female has to climb to the shore to lay her eggs in the wet sand. Interestingly, the sex of sea turtle babies is determined by the temperature in their nest. Of the three species in the Red Sea, the vegetarian Green turtle is the most regularly encountered by divers at Eilat. The Hawkbill turtle is rare, easily distinguished by its sharp, curving beak and tiled dorsal scales. It feeds on sponges and other reef sedentary animals, but juvenileseatplankton.Throughouttheworldseaturtlesareconsideredendangeredspecies.Theyarehunted,andtheireggstakenbynest-robbers.Turtlesarefondofjellyfish,andarequiteoftentempted to swallow pieces of plastic bags, leading to intestinal blockage and possible death. Several turtles in the“CoralWorldPark” inEilat layeggseveryyear inanartificialsandhatchery, and their offspring are released to reinforce the natural population. Eilat’s shore is mainly covered with coarse rock debris, not ideal for sea turtle nesting. Nevertheless, in 2007 one female Green turtle laid her eggs in the Nature Reserve beach. Baby turtles emerged after two months and ran into the sea. Special measures are taken to keep the beach dark at night to preserve anenvironmentfitfornestingseaturtles.

Hawkbill Sea Turtle (Erethmochelys imbricata):Above,juvenileandbelowatypicaladultmoveacrossthedeeperlagoon.Photo: M. Levin

Whales: Dolphins and kinWhales, the order Cetacea, are marine mammal predators. The large cetaceans, plankton-feeding baleen whales, are absent from the Red Sea, the smaller ones, of the family Delphinidae, better known as dolphins, are common. The most common one is the Bottlenose dolphin (Tursiops adduncus), whose natural schools swim freely in the Gulf. Less common are the open-sea Pantropical spotted dolphins. They are spotted mainly far from shore. Both are small dolphins, 2-2.5 m long. Still rarer is the dark-colored False killer whale, a relative of the oceanic killer whale (Orca). The “Dolphin Reef” inhabitants are Mediterranean bottlenose dolphins (T. truncatus), imported from the Black Sea. They are larger than the local species, reaching the length of 4 m. The “Dolphin Reef” trainers dedicate considerable time and effort to monitor the wild dolphins in the Gulf. Most of the lonely dolphins in Eilat’s vicinity are named and observed by them. The female Holly left her natural school and lived for several years next to a Bedouin village,maintainingcloserelationswithablindfishermaninNuweiba,Sinai,andwasatouristattraction for years. She used to swim with the Dolphin Reef’s dolphins outside their enclosure. Shewaskilledbyfishermen.Threeofhercubs,bornseparately,diedalsoduringthelastdecade,in unexplained circumstances. Marco is a juvenile bottlenose dolphin,whosemother died inunknown circumstances in Aqaba several years ago, and he became attached to divers at Eilat.

Dolphins in Eilat: False Killer Whale (Pseudorca crassidens), Spotted Dolphin (Stenella attenuata) and a small school of Red Sea Bottlenose Dolphins (Tursiops adduncus). Photo: O. Armosa

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Moderating the Human impactHumaninfluenceontheseaisinevitable.Technologyandhumanactivitycausestressandkillseaanimals. It is our duty to do everything possible so that our encounters and interactions with these organisms will be as tolerable as possible, even at the price of our own convenience. We have to protect the marine environment from evil-doers, either purposeful or unintentional. The seascape may include man, but his activity and footprints should disturb its welfare as little as possible. We shall present here some aspects of these activities.

A Rusty Parrotfish (Scarus ferrugineus) seeks shelter at night inside a boat wreck, adorned by ahermatypic colorful corals. Theambiguousattitudetowardsartificialobjectsisenhancedbythepotentialshelteritprovidesforcertainreeffishes.Photo:M. Levin

1.What is species diversity?2.Pollution:definitionandpollutiontypes3.Coralpredationunderecologicalstress4.Coralsettlementonartificialsubstrates5. Abandoned structures – what is their fate?6. Species disappearance and reappearance7. Coral nurseries8.“Tamar”artificialreef9. Diving and underwater activities

10. Shipwrecks as diving sites11. Underwater photography12. Diving sites in Eilat13.EilatCoralNatureReserve14. Coral World Underwater Observatory15. Dolphin Reef Resort16. Underwater restaurant17. Educational Nature Reserve

High Diversity

Low Diversity

Diversity: the variety of species in a sample, community, or area. In these pictures two reef patches are shown, the upper showing a high diversity of small coral colonies of different species, whereas the lower picture shows large colonies of 1-2 species, and low variety of smaller colonies, i.e. Low diversity. Photo: J. Dafni

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PollutionDefinition: an undesirable state of the natural environment being contaminated with harmful substances as a consequence of human action.

Types of pollution• Chemical pollution: introduction of chemical contaminants into a water body.• Terrestrial waste pollution: waste dumping into the water, e.g. garbage, sewage.• Thermal pollution: introduction of heated water into the sea. This reduces oxygen and causes

thermal stresses in animals.• Genetic pollution:influxofgeneticallyengineeredlivingmaterials.• Introduction of exotic creatures that may replace or change the original fauna and flora.• Euthrophication: enrichment resulting from chemical input of excessive nutrients, resulting

in excessive algal growth.• Noise disturbances: noise that may interfere with communication of natural organisms.

Marine mammals are highly affected by this disturbance.• Light disturbances: artificial change in the light regime thatmay affect the naturaldiel

periodicities (e.g. sea turtle hatchlings failing to navigate to the sea).• Physical damage to reefs and other habitats (breakage of corals, etc.).

The different types of pollution affect organisms in many ways. They reduce their resistance to disease or parasitism, and cause their demise. Generally, a pollution-free coral reef environment has a high diversity of corals and accompanying invertebrates andfish,which translates intoattractivenesstodiversandbeneficialrevenuetothelocalcommunity. A special effort is being made to facilitate access of a wide range of visitors to the reef in the form of an underwater observatory, coral reef nature reserves – while imposing strict rules and excluding divers from some areas. Divers who earlier complained of these rules and exclusions are beginning to cooperate, and the damage done by them seems to be decreasing. The entire humancommunitywillbenefitasaresult. Different pollution factors were discovered throughout the last decades that caused a notable decrease in biological diversity: Oil pollution from oil port and marine tankers, phosphate pollution, from both Eilat and Aqaba ports, sewage spills and other pollution sources. Several of these sources were reduced, but the danger that is caused by the urbanization processes and coastal development is still imminent. Only public awareness and consistent treatment of most threats will ensure the prosperity of this underwater habitat.

Effects of chemical pollution on reef inhabitants: two types of skeletal deformities in the Shortspine Velvet Urchin (Tripneustes gratilla elatensis) from the northern beach; “Goggle eyes” in the White-Edged Soldierfish (Myripristis murdjan). It is uncertain whether pollution or maltreatment is responsible for this last deformity. Photo: J. Dafni

Coral PredationLike any other animal, corals are threatened by many predators. Some, such as small gastropods, seastars and butterflyfishes consume the living tissue, whereas others, such as parrotfishes and pufferfishes, break off pieces of coral to extract the living tissue and the symbiotic algae within. It is known that pollution promotes the survival of undesirable predators or parasites that are otherwise kept in low numbers. In a polluted site on the northern shore of Eilat an outbreak of Drupella, a predator snail of branched corals, was observed during the early 2000’s. Hundreds of snails attacked all types of corals there and killed them. Another corallivorous snail, Coralliophila, which attacks only the coral Porites, was also abundant there. An alternative explanation – that wrasses, known predators of these snails, were missing, and thus the snails grew unchecked – was also suggested to explain this phenomenon. A later visit showed that indeed, all the corals there died, and the snails disappeared along with the corals. The Crown-of-thorns sea star, a known coral predator, also increases its populations in disturbed reefs.

Coral predators: Coral Predating Snails (Drupella cornus), gather to devour a Brain Coral (Platygyra), Corallivorous Snail, (Coralliophila neritoides), crowded on a Boulder Coral (Porites lutea) (Inset shows the typical violet aperture of the snail), a Crown-of-thorns Sea Star (Acanthaster planci) and Threadfin Butterflyfish (Chaetodon auriga) consuming stony coral polyps. Photo: J. Dafni, M. Levin

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Artificial reefsIntroducing artificial substrates that may be populated by marine sedentary organisms willencouragetheincreaseoffishandinvertebratepopulationstocompensateforover-exploitationof thenatural reefs. Ingeneral, artificial reefswill increase the carryingcapacity forfishandinvertebrates in the northern Gulf of Aqaba that otherwise is considered a “blue desert”. Some of theseartificialreefsmaybeattractivetargetsfordivers,helpingtoreducethedensityofdiverson the natural reefs.

Iron pilings of piers and marine scaffolding are covered with soft corals, sponges and ascidians, and is rapidly populated by fishandotherreeforganisms,practicallybecomingartificialreefs.Inset:ABroccoli coral (Dendronephthya sp.) hanging from an iron beam. Photo: M. Levin

Artifacts – take them or leave themObjectssuchasthisraiseadilemma:toremovetheseartificialobjects,justlytermed terrestrial waste,orleavethemunchanged.Artificialobjectsmayhoweverprovidehidingplacesforjuvenilefishes,spawningsitesforcuttlefishesordaylightrefugefornocturnalfishes.

A pipe sticking out of the sand has become covered with the Encrusting Soft Coral (Rhytisma sp.) and the Clownfish Anemone (Entacmea quadricolor) along with its symbiotic Clownfish (Amphiprion bicinctus). Photo: J. Dafni

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Hoist a thrown stone…An old proverb says “One fool throws a stone in the well and a thousand wise men can’t retrieve it”Artificialobjectsthrownintotheseamanyyearsagoposeanotherdilemma:intakingthoseout you may cause damage to the environment, but leaving them in is equally wrong. The solution maybetotrytoburythembeneathartificialreefcomponents–brokencoralboulders,transplantedcorals, etc. Some of these artifacts attract divers.

Nothing more to say. Photo: J. Dafni, M. Levin

Man-made Structures as habitatThemainsedentaryorganismsthatsettleonmetalobjectsintheseaaresoftcorals,spongesandtunicates. The question why some materials and surfaces are unattractive to both coral types is a commendabletopicforresearchandexperiments.Anartificialreefisdefinedas“aman-made,underwater structure, typically built for the purpose of promoting marine life in areas of generally featureless bottom.”

Even the repulsive appearance of an underwater garbage dump such as this holds some promise for a pair of Red Sea Bannerfishes (Heniochus intermedius),attractedtothesoftcoralsthatovergrowtheironobjects.Photo:M.Levin

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Faunal fluctuations, they come and go…Long term observations on the distribution of mollusks and other invertebrates show great fluctuationsofmanyspecies,fromabundancetoneardecimation.Thesefluctuationsarepartlynatural occurrences and partly the result of pollution.

Mollusks andcrabs thatunderwent extremefluctuationsobserved in a long termstudy.Above: Trush cowry (Erosaria turdus), covering its shell with its polishing mantle, replaced the Twin-blotched Cowry (Erosaria nebrites) that was common during the 1980’s; Land hermit crab (Coenobita scaveola), a nocturnal beach prowler, that hides during the day under rocks or among rubble. Once common, Sea harp, (Harpa amouretta) entirely disappeared. Bottom: once common, now rare or gone (left and clockwise): Strombus mutabilis, Gibberulus gibberulus, Erosaria nebrites, Casmaria ponderosa, Bursa grannularis, Murex ramosus, Terebra maculata, Modiolus auriculatus, Laevichlamys superficialis, Cardites rufa and Tellinella virgata. Photo: J. Dafni

Coral NurseriesThe natural recovery of coral reefs may take many years. The damage to natural coral reefs across the tropics in the wake of the 2004 tsunami accentuated the need for an alternative “gardening” technique to rehabilitate denuded reefs. A nursery component in an active reef restoration program is a tool that provides coral source material for the rehabilitation of denuded reefareas.Here,amid-waterfloatingcoralnurseryispresented,animprovedprototypeofearlierattached-to-substrate coral nurseries off Eilat’s northern shore. Thousands of fragments from coloniesofbranchingandmassivespeciesweregrownonanartificialsubstrateatasix-meterdepth,14metersabovetheseafloor,closetofish-farmingfacilitiesinthisarea.Totalmortalityof fragments during 10 nursery months was very low (less than 10%) while growth rates were high(upto6-foldinheight).Atthatdepththenurserygetssufficientlightanddoesnotinterferewith recreational activities. Mariculture procedures include removing sediments and protection against corallivorous organisms.

AcoralnurseryoffthenorthernshoreofEilatissuspendedonanet,14mabovetheseafloor.Photo:S.Shafir

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“Tamar” Artificial reefBased on the observations mentioned above, and considering the various factors that may determine thepreferablematerialsandspatialmorphologyforanartificialstructure,anexperimentalartificialreef has been erected, and a study devised, which will answer the following questions:

• Willthisstructurehaveaneffectonthelocalenvironment?• Willfishandother(noncoral)invertebratesacceptitandsettleintoit?• Willitcontributetoincreasethecarryingcapacityofthenaturalreef?• Willthecoralcommunitysettledonitbestable?• Willdiversfinditadesirablelocation?• And finally, can it be used to lure divers away from natural reefs and onto artificiallocations?

This research is carried out by Ben-Gurion University of the Negev, Eilat Campus in cooperation with the Authority of Nature ProtectionandfinancedbytheUSAID-MERCandWhitely Foundation,asajointIsraeli-Jordanianproject.ThelocalcoordinatoroftheprogramisDr. N. Shashar. The Interuniversity Institute and the National Center for Mariculture provide scientificsupport.

The “Tamar” concrete artificial reef was constructed by the Israeli company OBS, andsunkonanoffshoresandflatintheEilatNatureReserveinApril2007.Fivemonthslater,coralfragments (nubbins) of several species were transplanted from a nursery into prefabricated holes in the concrete structure. Preliminary results look promising - coral fragments have adapted to the substrateandfisharealreadyattractedtothenewenvironment.

Elevencoralspeciesweretransplantedintheproject; in situ fragmentbatch.Photo:S.Shafir

“Tamar” Artificial reef

The concrete and metal parts were prefabricated in the country’s center, brought to Eilat, sunk, and assembled in situ. Five months later coral fragments (inset) were transplanted into small holes in its surface. A Broomtail Wrasse shows interest in moving in. Photo: M. Levin, J. Dafni

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Divers – what are they up to?Eilat’s reefs accommodate a record number of divers. They support many diving clubs, hotels and local guides and provide the community with high revenue. Yet their impact on the reef may beharmful:breakingcorals,raisingsandwhichsettlesonthecorals,chasingfishesoutoftheirshelters, and other undesirable activities. Measures taken by the Nature Reserve Authority have started to show some results. Habitats that suffered serious damage have started to improve. Strict enforcement, combined with self-discipline on the divers’ side, encourages our belief that Eilat’s reefs will survive, and that the corals and divers will live together for many years to come. Photo: J. Dafni

ShipwrecksShipwrecks are the remains of ships sunk in storms or by hostile activity. Apart from their archaeological or historical importance, wrecks in shallow water turn out to be favorite diving sites.Thecoverofalgae,spongesandcolorfulsoftcoralsattractsfishandothermarineorganisms.Fortunately the coast of Eilat has not witnessed any marine disaster, but small and medium size ships have been deliberately sunk to increase the carrying capacity of the northern part of the Gulf for fish and to provide diverswith picturesque diving sites.The best-known shipwreckin Eilat is the military vessel “Sufa”, a missile boat that served for 20 years protecting Israel’s Mediterraneanshores.Itshistoryisquiteeventful.ThiswasoneoffivenavalboatsthatIsraelbought from France in the early 1960’s. It was built in Cherbourg harbor, but after the Six-Day War in 1967, French President Charles de Gaulle declared an embargo on the sale of military equipment to Israel. Diplomatic efforts to free the boats failed, and on Christmas Eve, 1969, the Israeli missile boats - which had already been paid for - sneaked out of the harbor to the open sea and sailed to Israel. They were known as the “Boats of Cherbourg”. The long service of the “Sufa” ended in 1994, when it was purposely sunk off the coast of Eilat in 27 meters of water. Other naval boats like the “Yatush” were also sunk in the vicinity, and they have become an important co-production of technology and nature.

Divers survey the ship’s hull and growth of corals on deck and on the bridge structure of the “Sufa” wreck. Photo: M. Levin

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Underwater photographyThis is the modern form of hunting. Taking pictures in a non-destructive way is advantageous to nature in a variety of ways: it enhances awareness of sea life, provides data on animal behavior, and records problems developing in the natural environment. It might however be destructive ifphotographersencroachuponsmallfishesorslugs,disruptingtheirroutineandendangeringtheir very existence. Considerable effort should be invested in education and enforcing proper regulations to prevent damage by too enthusiastic photographers.

Underwater photographer in action. Photo: M. Levin

Diving sites in EilatThe short, ca. 15-km long coast of Eilat offers the diver many diving sites. In this short account, based on the popular Hebrew Book “44 Diving Sites along Israel’s Coast,” we list here a dozen sites and point out the highlights of each and their maximal depths (according to safety regulations). The reader should consult one of the many local diving clubs for updated information on new attractions and for regulations and limitations concerning diving at these sites. A local diving “buddy” is highly recommended.The sites (from north to south) are:1. The Pyramid:artificialreefandobjectsoffthenorthernshore(depthupto32m)2. Wadi “Dekel”:drownedwadi,reefandtopographicalviews(upto30m)3. “Dolphin Reef”:aprivatebeachresort:reef,naturalandartificial,divingwithdolphins (<10 m) – entrance fee. Diving is only via the Dolphin Reef Club.4. “Sufa” Wreck: known locally as “Satil” – a naval boat wreck (see page 169) (depth 27 m)5. “Yatush” Wreck and Garden Eels: another small “wreck” and natural reefscape (depth33m)6. Coral Beach Nature Reserve: a protected area. Includes Joshua and Moses Rocks. Entrance

fee.DivingorganizedbyEilaticlubs(depth33m).Nonightdives.7. “Japanese Gardens”: a protected area. Entrance only by boats. Entrance fee. Diving

organizedbyEilatclubs(depth30m)8. The “Caves”: opposite the Lighthouse. A shallow dive (depth 5 m). 9. “Veronica Shore” (shallow): shallow dive along the coast. Starting south of the Lighthouse

(depth 6 m)10. “Veronica Shore” (deep): deeper dive along the coast. Starting opposite Princess Hotel,

diving northwards (depth 24 m)11. “Princess Hotel” dives: deeper dive. Beautiful coral knolls. Entrance through the hotel’s

southern seaward walkway. Closed at night (depth 25 m)12. “Neptune’s Tables”: next to the Egyptian border is a large concentration of flat-topped

branched corals, partly capsized. Entrance and exit from the Princess Hotel beach (down to 25 m)

Important notice: Along the Israeli Coast it is forbidden to dive solo. Diving with knives, sharp metal instruments or spear guns is prohibited. For safety reasons, it is forbidden to swim beyond thefloatlinewheretheareaisopentoboattraffic.Divingbelowitispermitted.Alongthesouthernshore, enter the sea via designated entrance points. Further information is available in the above-recommended book (alas, only in Hebrew).

Photo: M. Levin

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Eilat Coral Nature ReserveAlthough theentireshore lineofEilat’scoralsandcoral reefs isprotected, theofficialCoral Nature Reserveextendsalonga1.5kmstretchoffencedbeach(entrancefeerequired),and3km of open shore with free access. This is a preferred diving site.

A fringing reef along the shore of the Nature Reserve protects a narrow lagoon. Along the seaward drop of the front reef, coral colonies and patch reefs – the “Japanese Gardens” – continue to a depth of 50m and more (picture taken from the underwater observatory walk-bridge). Inset: annual exposure of the reef flat due to extremely lowtide. Photo: J. Dafni

Opposite page: the most impressive habitat of the Nature Reserve is the 8-10 m high Moses Rock. It is rich in plankton-feedingfishandcolorfulsoftcorals.Intheshallowlagoonsbouldercoralsandflat-toppedbranchedcorals(pp44,157)dominate,nexttolargegiantclams(page83).Photo:J.Dafni

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Underwater Observatory Marine ParkIn1974thefirstunderwaterobservatoryintheworldcameintobeing.Ametalstructuresunkinto10mdeepwateroftheEilatNatureCoralReserveofferedinthefirsttimedirectobservationintothedomainofthecoralsandcoralfish.Fromtheviewpointofnatureconservation,itisagolden opportunity to introduce thousands of people to the underwater world without intervening with the ecological system. Through the windows and in the many aquaria in the park, hundreds offishandinvertebrateanimalsliveinanalmostnaturalhabitat,sincemanyof theseanimalsenter the park as larvaeintheseawaterinfluxdirectlyfromthesea.Thedisplayedcorals,seaanemones,andmanyotherseaorganismsglowunderthefluorescentlightoftheaquaria(nextpage),inasplendorthatcannotbeseeninnature.Rarefishes,andevencommonones,shytothehuman observer, like the Flashlight fish,liveintotaldarknessandflickerwiththeirlight-emittingorgan to lure small prey to theirmouth. In special aquaria, juvenilefishes of extremebeautyare displayed. Educational programs carried out by the “Coral World” team for local k-6 pupils rehabilitate broken corals and facilitate sea turtle and seahorse reproduction for their later release to the sea. A visit to the park is a must, even for the experienced diver.

Theunderwaterobservatory;Panoramicviewofthe“Eilatreef”circularAquarium;Exquisitecoralsandfishdisplayintheaquaria department. Photo: J. Dafni

Where else…Where else would you meet a curious parrot fishlookingatyoufromclosedistancewithoutgettingwetoralarmingthefish?

Where else would you see a large variety of reef fishes that call this artificial metalframework home?

Where else can you see living corals at full size, glowing mysteriously in eerie light conditions?

UnderartificialilluminationappliedintheCoralWorldaquariatheproteinsinthecoraltissuesandtheirsymbiotic algae glow.Thescientificexplanationisthatonlypartoftheultravioletlightenergyisabsorbedbythecoraloritssymbioticalgae,and the remaining energy is emitted as light in the visible spectrum. This phenomenon cannot be seen in nature. Photo: J. Dafni

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The “Dolphin Reef”The Dolphin Reef is a recreational site that includes an enclosed public swimming area and a wide space for a school of captive bottlenose dolphins. The dolphins are treated by the trainers with respect and trust as they carry on their normal daily routine of feeding, breeding and playing. Small reef patches and the fence between the two areas are populated by many invertebrates and fish.Themainattractionofthissiteistheopportunitytodivewiththedolphinsinanaturalcoralreefcombinedwithanartificialreef.Visitorscanwalkalongafloatingbridgetothedolphins’areatowatchthem.Ipersonallyenjoysnorkelingalongthenetfenceborderingthedolphins’enclosure,next to the public beach with its supple growth of corals and colorful fouling organisms.

Above: Diver and instructor on an introductory dive with a dolphin. Below right: A white soft coral growing on the fence bordering the dolphins’ enclosure next to the public swimming area. View from the reef knoll of Black Ascidian and Basslets; andabeautifulcamouflagedTunicate (Halocynthia sp.). Photo: J. Dafni

Underwater RestaurantIt is a very unusual restaurant in that it is located underwater, 5 m below sea level in the vicinity oftheUm-Rashrashsite(overleaf).Itissurroundedbywindowsfacinganartificialreef,richwithsoftcorals,spongesandfish.Through thewindowsavividpanoramaappearsduring theday,shiftingatnighttoaghostlyvisionofdiurnallyactivefishtakingshelteramongthecoralswhilenocturnal predators emerge from the dark, approaching and peeping through the windows.

Awalk-bridgeconnectstheunderwaterrestaurantwiththeshore,artificialreefteemingwithcolorfulcoralfish,andafishschool gathering at the restaurant windows. Photo: J. Dafni, M. Levin

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Educational Coral Reserve“Um-Rashrash Reef”OnMarch10,1949thefirstIDFsoldiersarrivedinEilatinamilitaryoperationthatconcludedthe War of Independence. Upon reaching the shore they found several mud huts and a God-forsaken police station named Um-Rashrash, andhoisted thenow-famous“inkflag”.On thebeachoppositeUm-Rashrash(presentlyamemorialsite)theyhadtheirfirstexperiencewithRedSea marine life in the form of sea urchin spines. The small coral reef, said to be the northernmost coral reef in the world, has survived all events since and is now one of Eilat’s swimming beaches. Lately a plan has been initiated to make this reef an Educational Coral Reserve. On the reef andintheadjacentlagoonandintertidalzone,morethan50coralspeciesandover100fishandinvertebrate species have been recorded. Many of them appear in this book.

Um-Rashrash Reef, General view: Pajama Slug (Chromodoris quadricolor), Brain Coral (Platygyra sp.) and a giant Boulder coral (Porites sp.). Photo: J. Dafni.

The programmed activities in the Educational Reserve include guided swims and dives, studying thenaturalhabitat,andindividualstudentlearningprojects.Beingapublicbeachwithallnecessaryfacilities and an easy approach to the reef and other habitats assures coexistence between nature and human activities. Only wise and sustainable development will preserve this natural habitat.

SomeoftheReserveinhabitants:juvenileLionfish (Pterois miles), a large colony of Plate Coral (Turbinaria), a slightly damaged very large Lobed Coral (Lobophyllia corymbosa), and an Anemone Carrier Hermit Crab (Dardanus tinctor). Photo: J. Dafni, I. Ben-Tov.

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Eilat Coral reefs in the 21st centuryCan we return to the pristine 1960’s? Probably not, but we can preserve seawater quality and protect theremainingcoralreefs.Furthermore,artificialreefsandstructuresliketheoneillustratedbelowcan serve as substrate for corals and their accompanying fauna, preserving Eilat’s underwater environment as a tourist attraction for ages to come.

Eilat 1966

Eilat 2006

Photo: M. Levin Photo: J. Dafni

How will Eilat’s coral reef fare at the mid-21st century?Throughout the world, coral reefs will be in constant danger emanating from climate change. Global warming and environmental pollution have already affected coral reefs throughout the tropics. The same may well apply to our coral reefs, which are dangerously close to a commercial harbor, industrial facilities and urban and recreation centers. The human population density poses a dilemma - whether to turn the reef into a backdoor coral garden, or set a limit to the extent of human exploitation by visitors and divers at all costs. How can we both “have our cake and eat it, too?” Eilat’s coral reef is too dear to let it be neglected or mistreated. Its exploitation must use sustainable development principles that will ensure that this natural resource will not fall victim to developers’ zeal. Itiswellknownthatfishandinvertebratebehaviorisstronglyaffectedbyhumanintervention.A group of several divers mobbing a small seahorse, slug or octopus interferes with their routine activity, causing them long-lasting trauma. Therefore Iwant to put forward several ideas thatmay enable large crowds to enjoy theencounter with coral reef life without placing an extra burden on the environment. One option is theuseofhightechnologytosparemarineorganismsfromhuman-inflicteddamage:

1. Creating hiding places for divers to approach and observe marine organisms without interfering withtheirnaturalhabits.Theycanbeincludedinthedesignofartificialreefs,enablingdiversto witness extraordinary activities in situ, such as the Eel gardens, shipwrecks etc.

2. Placing tele-operated cameras at ‘strategic’ points in the reef environment or on board unmanned submarines and relay audiovisual material to an auditorium ashore. The aim is to show it to the public in real time, instead of their swimming onto the reef. The relay can be used also as database material or in research.

3. Photographedfootagecanbesoldtovisitorsorbroadcasted.4. Asubmarinesculpturegarden,createdbyskilledartistsonunderwater shallowsandflats,

empty of corals, will attract divers both for its artistic value as well as for the combination ofcorals andother sedentaryorganismattached to it.Suchartificial reefs aremuchmorevaluable and attractive than ordinary artificial reefs. It should be built fromdurable non-corrosivematerialssatisfyingtechnicalandsafetyspecifications.

5. An electronic database of the animals and plants on the reef, available to the public, will be (a)anidentificationaid,(b)achecklistforthepresence/absenceoflivingorganisms,and(c)a basis for long term monitoring of the natural populations.

6. A periodical bulletin issued by local experts will increase awareness of the coral reef, and monitor seasonal and long-term changes.

Thebehavioroffishandmarineinvertebrates,especiallythemutualrelationsbetweenthemareanimportantresearchtopicthatwillkeepmanyscientistsbusyinthefuture.Here,unexplainedrelationshipbetweentwofishes–parasitism,symbioticrelationship or what? – Yellow Goatfish (Parupeneus cyclostomus) and a female Bird Wrasse (Gomphosus coeruleus). Photo: J. Dafni

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Further ReadingDafni. J. (1995) Eilat: Routes and trails in the Eilat Region. Gefen Publishing House, JerusalemDafni, J. (2000) Gulf of Eilat, from the Red Sea to the red line. Cherikover Publishing Company, Tel Aviv (Hebrew)Dafni, J. (2008) Eilat’s Coral Reefs, optimistic view. Yeela Publishing, Eilat (Hebrew)Debelius, H. (2001) Red Sea Reef Guide. IKAN, FrankfurtDor, M. (1984). CLOFRES: Checklist of the Fishes of the Red Sea. Israel Academy of Sciences and Humanities, JerusalemEdwards, A.J. & Head, S.M. (Eds.) (1987). Key Environments: Red Sea. Pergamon Press, OxfordGur, A. (2004) MAPA’s Guide to Israel’s Best Diving Sites. MAPA Publ. Tel Aviv (Hebrew)Marco, S. (1988). The Geological History of Israel in light of Plate Tectonics. Eilat Field School Publication (Hebrew)Por, F. D. (1978). Lessepsian Migration: The Influx of Red Sea Biota into the Mediterranean by Way of the Suez Canal. Springer, BerlinRandall, J.E.(1983).Red Sea Reef Fishes. 192 pp. Immel Publ. Co., LondonReiss, Z. & Hottinger, L. (1984). The Gulf of Aqaba: Ecological Micropaleontology. Ecological Studies no. 50. Springer, BerlinRichmond, M. D. (ed.) (1997) A Guide to the Seashores of Eastern Africa and the Western Indian Ocean islands. Swedish International Development Cooperation Agency (Sida)Schuhmacher, H. (1976) Korallenriffe. BLV GermanyShpigel, M. (1997) Fishes of the Red Sea. Red Sea Magazine, Ra’anana, IsraelVine, P. (1996) Red Sea Invertebrates. Sea Challengers Publ. Co., LondonYonow, N. (2008) Benthic Opisthobranchs of the Red Sea,PensoftPublishers,Sofia

From the same author:

EndnotesAs the reader might have already noticed, the gallery of animals that take part in the ecological wonder of the reef is wide, and is still revealing new secrets – new kinds of animals, new ways of life, new insights. Eilat has its roots in the sea. The coral environment is its main attraction. Small as it is compared to the vast areas and long beaches of neighboring countries, Eilat offers a more qualitative approach to the sea. Three academic institutions practice marine biology and ecology in Eilat, and other educational institutions study its economical potential, and its preservation. The Underwater Observatory Marine Park is unique. It is not as spectacular as the huge aquaria and museums of the largest cities in the world, but it is connected to the sea. It is within a coral beach, and many of the smaller organisms inside its tanks came from the sea as larvae. ThefirstunderwaterobservatorywasestablishedinEilat,aninventionthatenablesvisitors tomeeteye-to-eyethefreereeffishesthatapproachbytheirownchoice,curioustomeetthehumansacross the observatory window glass. This book displays only a small sample of the large variety of life forms revealed in the Eilat reef environment. Many more can be seen in the observatory and in the Park’s aquaria.Throughout the world, coral reefs are losing ground alarmingly. Pollution reduces their diversity; global seawater warming causes coral bleaching, a phenomenon of zooxanthellae expulsion from their coral host, leaving it to die, along with predation of corals by sea stars and other predators and coral diseases; and on top of the other plagues, there is the over-exploitation by fishermenanddiversalike.Luckily, the Gulf of Aqaba (Eilat) is only slightly affected by these factors. The cooler water prevents bleaching, pollution is relatively mild, and other factors are - partly, at least - under control.Public support is vital to protect the reefs, to rehabilitate damaged habitats and to monitor and foresee any danger to this fragile ecosystem.

As author I wish to acknowledge the help of many divers who trusted their photographs with me, especiallythoseofthe“Tapuz”websitediversforum,whoreplacedthefishing rod with a camera: Y. Aharoni, O. Armosa, I. Ben-tov, R. Biran, M. Chen, R. Cohen, A. Colorni, L. Dafni, A. Diamant, Y. Esh, J. Grinfeld, A. Gur, E. Halevi, A. Kendler, R. Koslawsky, O. Lederman, B. Levi, K. Levy, A. Lynn, E. Meidan, Z. Movshowits, L. Pintchover, B. Tamir, S. Shafir, N. Shashar, M. Shpigel, A. Stern, D. Weinberg and D. Zakai.Special thanks are due to Michael Levin, whose observations and photographs broadened the book’s scope. Dr. Jeffrey Gansburg and Mr. Binyamin Koretz reviewed the English text, and their contribution is highly appreciated.To the organizations and individuals who supported the publishing of this book.To my family, who supported my old craving for unfolding the sea’s secrets.To my daughter, Lior Dafni, who designed and shaped the book. Jacob Dafni

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GlossaryAhermatypic: non-reef-building corals.Alpha female: the individual dominant female in the community.Ampullae: medusa forming polyps in hydrozoans.Anal fin:thefinbehindthefishanus.Anal:oftheanus(=vent).Anthocaulus: Juvenile attached polyp of mushroom corals (pl. anthocauli).Aristotle’s lantern: mouth-apparatus of a sea urchin.Asexual: reproduction not involving the union of male and female germ cells.Atoll reef: circular or continuous barrier reef surrounding a lagoon.Atrial: of the atrium (in sea squirts).Autozooid: a fully developed polyp (in corals).Azooxanthellate: not having zooxanthellae, contrary to zooxanthellate.Baleen:insomewhales,thecomb-likefibrousplateshangingfromtheupperjaw,usedtosievefoodfromsea water.Barbels:Whiskerslikeprojectionsthathelpthefishlocatefoodinthesand.Benthic: pertaining to the bottom of a sea, the Benthos.Bilateral symmetry: with left and right sides that are approximately mirror images.Bioherm: A rock structure built up by sedentary organisms, as corals,algae,mollusks(=reef)Blastula:ball-shapedfirstlarvalstageinmulti-cellularorganisms.Bleaching: discoloration of zooxanthellate corals, caused by the death or release of the symbiotic algae.Bogus eyespot: eye-shaped color pattern, aimed to fool a predator.Browsing: feeding on higher vegetation- stems, leaves etc.Byssus:fibersissuingfrombetweenthevalvesofabivalveforattachment.Calcareous: made of calcium carbonate, chalky.Calcareous algae: containing calcium carbonate, chalky.Carapace: In crustaceans, the part of the external skeleton that covers the cephalothorax.Carnivore: an animal that eats other animals.Cartilaginous: made of cartilage (as in sharks and rays).Caudal: of the tail.Cephalothorax: combined head and thorax in crabs and lobsters.Chela: a moveable lateral toe like the claws of a crab or lobster.Cheliped:incrustaceans,thefirstpairoflegswhichbearthechela(claws).Chlorophyll: green pigments in plants that facilitate photosynthesis.Choanocytes:collarcells–flagellaebearingcellsinsponges.Cirri (fish):finspinessplittingtotassel-likefilaments.Alsofinger-likeclingingprocessionsinthefeatherstars (Crinoids).Cleaning station:locationwherefishandothermarinelifecongregatetobecleaned.Cnidocyte: The “stinging cell” of a cnidarian.Cnidosac: a sac of a nudibranch gastropod, containing undischarged cnidocysts.Commensal: “eating from the same table”- loose symbiotic relations.Corallite: skeleton produced by an individual polyp.Cuvierian tubules: defensive structures expelled through the anus of sea cucumbers.Dactylozooid: Stinging polyp in hydrozoans.Deuterostomia:majorgroupwithintheanimalkingdom,inwhichvertebratesincluded.Diel: a 24-hour period, usually encompassing one day and one night.Dorsal: pertaining to the back, or situated near to or on the back.Dorsoventral: axis between the dorsal and ventral sides.Endemic:confinedtoacountry,seaorland.Endosymbiosis: relations, where the symbiont lives within his partner’s body.Ephyra: the earliest free-swimming stage of scyphozoan medusa.Epifauna: fauna living on the ground.Errantia: worms with a freely moving lifestyle.Eukaryotic: cells containing internal organelles, especially a cell nucleus.Euthrophication: excessive primary production due to enrichment in nutrients.Extratentacular: form of budding in hermatypic reef corals.Fauna: all the animal life in a particular region or period.Flagellum:whip-likeorganelleofthecell.(pl.flagellae).Flora: all the plants in a particular region or period.Forereef: seaward facing reef end.Fouling:organismsgrowingonsubmergedboats,artificialsurfacesandpiers.Fringing reef: reef fringing the shoreline in shallow depth.Gastrozoid: Eating polyp in hydrozoans.Gill covers:lidorflapcoveringthegillapertureinfish.Gill slits:slitsorgillopeningincartilaginousfish.Grazing: feeding on low vegetation, such as grass.Guanine: one of the main nucleobases in DNA.Hectocotylus:armofmalecephalopodsmodifiedforfertilization.Herbivore: animal that eats only plant material.

Hermaphroditic: Having both male and female reproduction organs.Hermatypic: reef building corals, stony corals.High tide: high water level within the tidal range.Hydromedusa: medusa stage of hydrozoans.In situ: In its natural position or place.Intertidal: region between high and low tide.Intratentacular: polyp division in hermatypic reef corals.Irregularia: Sub-class in the Echinoidea showing bilateral symmetry.K-strategist: animal that grows slowly and lives longer.Larva: earliest stage of animals that undergo metamorphosis, differing from the adult (plural larvae).Lateral line:seriesofpore-likeopenings(tosensorycanal)alongthesidesofafish.Low tide: low water level within the tidal range.Mantle: an organ in mollusca, covering the body, secreting calcium carbonate tocreate a shell.Mariculture:marineaquacultureoffishandinvertebrates.Medusa:free-swimmingsexualstageofacoelenterate,suchasajellyfish.Mesogloea: Jelly-like middle layer in cnidaria.Monocotyledon:Anyofvariousfloweringplants,suchasgrasseshavingasinglecotyledon.Nekton:collectivenameforactiveswimmingorganisms,suchasfish,squidsetc.Notochord:along,flexiblerodwhichrunsthelengthofthebackinanimals belonging to the phylum Chordata.Nutrients: minerals needed for photosynthesis or life sustaining processes.Ontogeny: the development of an organism from egg to adult. Operculum: cover of a snail’s aperture, when it draws in.Oral: of the mouth. Oral arms:armssurroundingajellyfishmouthOscula (pl. of osculum): The mouth-like opening in a sponge, used to expel water.Ossicle: any small bone, embedded in soft tissue (Echinoderms).Ostia (pl. of ostium): any of the small openings or pores in a sponge.Pectoral fins:pairedbreastfinsinfish.Peduncle:thefleshyareatowhichthecaudalfinisattached.Pelvic fins:pairedventralfinsinfish.Petaloid:flower-likeinechinoids.Photosynthesis: process of turning CO2 to carbohydrate by plants.Pinnules: side branch structure on the tentacle of soft corals.Plankton: drifters, passive moving marine organisms.Planula: Larva of cnidarians (plural larvae).Proboscis: The elongated mouthparts, snout or beak.Prokaryotic: single-celled living organisms, not having cell nucleus.Protandrous:insequentialhermaphrodites,sexchangingfish-malefirstProtogynous:insequentialhermaphrodites,sexchangingfish-femalefirst.Quaternary: Geological period starting at ca 2 million years ago to present.Rachis: axis or central line of a sea pen coral.Regularia: Sub-class in the Echinoidea showing circular symmetry.Rift: a place where the Earth’s crust and lithosphere are being pulled apart.r-strategist: animal that grows quickly and dies sooner than a K-strategist.Sedentaria: collective name for sedentary polychaete worms.Sexual dimorphism: organism in which both sexes are different in shape or color.Siphon: tube-like structure in clams or octopuses, for passage of seawater.Siphonozooid: specialized polyp in colonial soft corals, which functions as intake for water.Spicules: skeletal structures that occur in sponges and soft corals.Spongin: protein building the structure of most sponges.Spring bloom: seasonal abundance of algae, occurring in early spring.Spring tide: excessively high and low tides, occurring twice a month.Stolon: horizontal stem which grows along the surface.Strike-slip: in geology, fault involve motion which is parallel to the strike of the fault.Swim bladder:agas-filledsacinfishesthatprovidesbuoyancy.Symbiotic: mutual positive relations (symbiosis) between two or more organisms.Tadpole stage: free-swimming larva of ascidians, with a tail like an amphibian.Test: a hard outer covering as of some amoebas and sea urchins .Tide: rising and falling of Earth’s ocean surface caused by forces of the Moon and the Sun.Transform rift: horizontal moving faults, such as in the Dead Sea Rift.Tubefeet:flexibletube-likelocomotionandattachmentsystemsin echinoderms. Valve: one shell of a clam, usually having two valves (shells attached at the hinge).Vascular: water and nutrient conductive tissue in plants.Ventral: of the belly, or lower side.Warning coloration: intended to make an organism more noticeable.Zooplankton: plankton consisted of animals.Zooxanthellae: unicellular yellow-brown algae living symbiotically in the tissues of corals.

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Scientific IndexAbudefduf saxatilis 122 Abudefduf sexfasciatus 122 Acabaria cf. erythraea 66 Acabaria cf. pulchra. 66 Acabaria cf. splendens 66 Acanthasterplanci3592159Acanthellacarteri.23Acanthopagrus bifasciatus 141 Acanthopleura vaillantii 10 Acanthurusnigrofuscus138Acanthurussohal138Acanthurusgahhm139Acroporacf.hyacinthus3540435152Acroporasp.4647123159166Actinodiscus nummiformis 72 Actinopyga bannwarthii 96 97 Aeoliscus punctulatus 110 Aetobatus narinari 106 Alpheusdjibutensis136Alpheusrubromaculatus136Alticuskirkii135Aluterus monoceros 147 Aluterus scriptus 147 Alveopora3559Amphiprionbicinctus1770123161 Anampses meleagrides 124 Anellahicksoni1367131Antennarius coccineus 152 Antennarius nummifer 152 Anthelia 64 Antipatharia 56 Antipathes cf dichotoma 56 Apogon annularis 142 Apogoncyanosoma135Argonauta argo 85 Arothron diadematus 150 Arothron stellatus 150 Ascidia 89 100 176 Aspargopsis taxiformis 21 Aspidontusdussumieri134Asterinaburtoni9293Asthenosoma marisrubri 94 Astroboa nuda. 98 99 Astropecten polyacanthus. 17 Atheloperca rogaa 107 116 Aurelia aurita 26 Bodianus anthioides. 124 Bothuspantherinus132Botrylloides spp. 100 Brachiodontes pharaonis 164Bursa granularis 164 Callechelys marmoratus 109 Calliactis polypus 70 Callispongia sp.. 98 Calloplesiopsaltivelis137Cantharellus35Cantharellusdoederleini38Cantherinus pardalis 147 Canthigaster coronatus 151 Canthigaster margaritata 151 Cardites rufa 164 Carapus 96 Carpilius convexus 89

Casmaria ponderosa 94 95 164 Cassiopeia andromeda 26 Caulerpa serrulata 20 Cellana eucosmia 10 Cephalopholis miniatus 116 Ceratosomamagnifica80Cerianthus spp. 72 cf. Cladopsammia 55 Chaetodon auriga 118 119 159 Chaetodon austriacus 119 Chaetodon fasciatus 118 119 145 Chaetodon lineolatus 118 119 Chaetodon paucifasciata 118 119 Chaetodon semilarvatus 118 Chaetodon trifascialis 118 Cheilinus lunulatus 91 125 167 Cheilodipterus quinquelineatus 142 Cheilodipterussp.135Chelonia mydas 154 Chicoreus ramosus 164 Choriastergranulatus93Chromis dimidiata 145Chromisviridis31122123145153Chromodoris quadricolor 22 178 Chrysaora / Pelagia 27 Chrysiptera annulata 122 Cirrhitichthysoxycephalus131Cirripathes anguina 56 57 Cirripathes sp. 62 Cladiella 65 Clionavastifica22Clypeaster humilis 91 94 102 Codium arabicum 21 Coenobita scaveola 174Conus tessulatus 88Coralliophyla neritoides 159 Coris aygula 102 124 Coris caudimacula 124 126 Corythoichthys schultzi 110 Crellacyathophora23Cryptocentrussteinitzi136Cryptodendrum adhesivum 71 Ctenactisechinata3839Cyclomycterus spilostylus 149 95 Cynarinalacrymalis38Cynoglossussinusarabici133Dardanus lagopus 88 Dardanus tinctor 16 179 Dascylusaruanus122123Dascylus trimaculatus 122 126 Dendrochirus brachypterus 114 Dendronephthyasp.60,63Dendropoma maxima 78 Diadema setosum 16 125 146 Dictyospaeria cavernosa 21 Diodon hystrix 149 Diploastreaheliopora3337Diplopriondrachi137Dromia sp. 89 Drupella cornus 159 Dunkerocampus multiannulata 111 Echeneis naucrates 19 106 Echidna nebulosa 108 Echinodiscus auritus 94 95

Echinopora333637Echinoporaforskaliana37Echinoporafruticulosa37Echinoporagemmacea37Echinothrix calamaris 94 Ecseniusgravieri134Engina mendicaria 77 Entacmea quadricolor 70 161 Enteromorpha clathrata 20 Epinephelus fasciatus 116 Erethmochelys imbricata 154 Erosaria nebrites 164 Erythrastrea33Euapta godeffroyi 97 Eucidaris metularia 94 Euphasia sp. 104 Euphendrium cf. ramosum 24 Eurypegasus draconis 112 Exaliasbrevis13495Faviacf.rotundata34Faviacf.pallida3437Faviafavus34Favialaxa34Faviastelligera3442Faviaveroni34Favorinus tsurganus 80 Filogranella elatensis 75 Fromiamonilis.93Fungiaspp.353839Fusinus polygonoides 79 Galaxea fascicularis 46Gobiodoncitrinus137Gomphosus coeruleus 124 181 Gonioporasp.33423559Gorgasia sillneri 109 Gracillaria 21 Grammistessexlineatus137Gymnomuraena zebra 108 Gymnothoraxflavimarginatus.108Gymnothorax nudivomer 127 Halocynthia 176 Halophila spp. 16 Hapalocarcinus marsupialis 89 Harpa amouretta 164 Hemigymnus fasciatus 124 Heniochus diphreutes 119 Heniochusintermedius119,163Herpolithalimax39Heteractis aurora 70 Heteractis crispa 17 70 Heterocentrotus mammilatus. 94 Heteroxenia sp. 61 Hexabranchus sanguineus 81 Hippocampus histrix 110 Holacanthus xanthotis 121 Holothuria atra 96 Holothuria edulis 96 Holothuria hilla 96 Holothuria impatiens 97 Holothuria nobilis 96 Hydnophora exesa 50 Hydractinia 24 Hymenocera elegans 92 Hypselodoris infucata 80 Iago omanensis 104 Idiomysis tsurnamali 72 998

Inimicusfilamentosus115Istiblennius edentulus 10 Istiblenniusrivulatus.134Isurus sp. 18 104 Labroides dimidiatus 125 126 Laevichlamyssuperficialis164Lambis truncata sebae 77 Lamprometra klunzingeri 99 Leptoseris explanata. 52 Limariafragilis83Lithophyllum 21 Litophyton arboreum 62 177 Lobophylliacf.pachysepta38Lobophyllia corymbosa 45 179Limariafragilis83Lithophyllum 21 Litophyton arboreum 62 177 Lobophylliacf.pachysepta38Lobophyllia corymbosa 45 179Lotiliagraciliosa136Lovenia elongata 94 Lysmata amboiensis 127 Macrophiothrix hirsuta 98 Manta birostris 18 106 Mauritia arabica immanis 77 Meiacanthusnigrolineatus134Meomeris annulata 21 Merulina cf. ampliata 52 Metopograpsus messor 11 Microcyphus rouseaui 94 Milleporadichotoma25134Millepora platyphylla 25 29 Modiolus auriculatus 164 Monacanthus spp. 147Montiporaspp.1346Mycalefistulifera22Mycedium umbra 49 Myrichthys maculosus 102 109Myripristismurdjan142143158Naosithoe 22 Nasolituratus139Nasounicornis139Nassa situla 79 Negombatamagnifica2262Nemanthusannamensis73Neopomacentrus miryae 145 Nerita orbignyana 10 Nodilittorina subnodosa 11 Octopus cf. cyaneus 85 Octopus marginatus 86 Opheodesoma grisea 97 Ophiocoma scolopendrina 11 Ophiocoma valenciae 98 Opiothrix propinqua 98 Ostracion cubicus 148 Ostracion cyanurus 148 Ovabunda macrospiculata 61 Oxycirrhtestypus67131Pachycerianthus 72 Pachyseris speciosa 49 Padina gymnospora 21 Palaemon debilis 10 Panulirus sp. 88 Papilloculicepslongiceps133Paracheilinus octotaenia 124 Paracirrhitesforsteri131Paraglyphidodon melas 122

Paralemnalia 65 Parapercishexophthalma102137Parapriacanthusransonneti63107Pardachirusmarmoratus132Parupeneusforsskali130Parupeneus cyclostomus 181 Pavona cactus 49 Pavona cf. varians 52 Pavona maldivensis 51 Pedum spondyloideum 82 Pempheris vanicolensis 144 Periclimenes imperator 127Periclimenes longicarpus 127Petroscirtesancylodon135Petroscirtesmitratus135Phronima sp. 101Phyllidia undulata 80 Pinna muricata 82 Plagiotremusrhinorhynchus135Platax orbicularis 141 Platygyra deadalea4347Platygyrasp.334458159178Plectropomus pessuliferus marisrubri 116 Pocillopora 41 Polinices mammila 79 Pomacanthus imperator 121 95 Pomacanthus maculosus 120 Pomacentrus sulfureus 122 Porites cf lutea 42 Porites cf. mayeri 47 Porites columnaris 14 48 Porites sp. 159 178 Priacanthus hamrur 142 Pseudanthiassquamipinnis113117143145176Pseudanthias taeniatus 117 Pseudobalistesflavimarginatus146 Pseudobalistes fuscus 91 146 Pseudobiceros Pseudoceros 75 Pseudochromisfridmani137Pseudorca crassidens 155Pteria aegyptiaca 82 Pteroides sp. 69 Pteroismiles107113179Pterois radiata 114 Ptychoderaflava16101Pygoplites diacanthus 121 Rhincodon typus 18 19 104 Rhinecanthus assasi 146 Rhytisma 161 Sabella sp. 75 Sabellastarte indica 74 Sabellastratecf.sanctijosephi75Salpa maxima 101 Sarcophyton 60 Sargassum sp. 21 Sargocentron diadema 142 Scarus bicolor 129 Scarus ferrugineus 102 156 Scarus gibbus 128 129 Scarus niger 129 Scarus sordidus 129 Scleronephthya 64 Scolopsisghanam130137

Scorpaenopsis diabolus 114 Scyllarides tridacnophagus 88 Sepia aculeata 84 Sepioteuthis sepioidea 84 Seriatoporahystrix3041Serpulorbis inopertus 78 Siderea grisea 108 Siganus luridus 140 Siganus stellatus 140 Sinulariasp.30Siphonochalinasiphonella1423Siphonophora 24 Solenostemus cyanopterus 111 Solenostemus paradoxus 46 111 Sparus aurata 141 Sphyraena barracuda 18 Spirobranchusgiganteus3174Stenella attenuata 155 Stenopus hispidus 127 Stichopus spp. 96 Stoichactisgigas123Strombus spp. 164 Stylophora41123Sufflamenalbicaudatus146Symbiodinium(=zooxanthellae)12 20Synanceia verrucosa 115 Synapta reciprocans 97 Syngnathus 111 Synodusvariegatus107133153Taeniuralymma105133Tellinella virgata 164 Terebra maculata 164 Tetraclita squamosa 10 Tetrosomus gibbosus 148 Thais hippcastanum 10 Thalassoma klunzingeri 124 Thaumoctopus mimicus 85 87 Thor amboinensis 71 127 Torpedosinuspersici105133Torquigenerflavimaculatus151Trachyphylliageoffroyi38Trapeziatigrina3192Triactis producta 71 Tridacna448388157172Tridacnamaxima83Tridacnasquamosa83Tripneustes gratilla elatensis 94 158 Trochus dentatus 76 Tubastrea cocinea 55 Tubastrea micrantha 55 Tubipora musica 68 Tubularia larynx 24 Turbinaria elatensis 21 Turbinaria mesenterina 49 179 Turbo radiatus 76 Tursiops spp. 155 Tutufa rubeta 76 Tylosurus sp. 126 Variola louti 116 Xyrichtyspavo153Zebrasomadesjardinii139Zebrasomaxanthurus139

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Common NamesAcabaria 66Acorn worm 16 101Adhesive Anemone 71Aeolidid slug 80Ahermatypic corals 54 55Anemone carrier crab 71Anemone mysid 72Angelfish120121Arabian cowry 77Arabianfangblenny135Arabiantonguesole133Banded boxer shrimp 127Bannerfish77Barbed wire black-coral 56 57Barnacles 10 25Barracuda 18Basket star 99Basslets113117145175Batfish141Bicolor puller 145Bigeye 142Bird wrasse 124 181Bird’snestcoral30Black ascidian 175Black corals 56 57Blackbarsurgeonfish139Blacklineblenny134Blackringedcardinalfish142Blennies10134135Bluetriggerfish91102148Boring sponge 22Bottlenose dolphins 175Boulder coral 14 42 -48 159 178Boxfish(=Trunkfish)148Braincoral43-4758159178Branched coral 40 41 45 65BranchedTablecoral43Brittlestar 90 98Broomtail wrasse 102 125 167Brown algae 21Bulldozershrimp136Burrfish149Butterflyfish118119Carrier hermit crab 16 179CauliflowerCoral41Cave sweeper 144Cephalopods 76 84 85ChevronButterflyfish118Chiton 10 76Christmastreeworms3174Circularspadefish141Citrongoby137Clam-killer lobster 88Clams 164Cleaner shrimps 71 126 127Cleaner wrasse 125 126Clearfinlionfish114Clown wrasse 124Clownfish1770122123161ClownfishAnemone70161Coloredbroccolicoral63160Columnar corals 48Combjellies19Commensal Anemone 70Conch snails 164

Cones snails 76Coral burying clam 82Coralcrabs318992Coral gall crab 89Coral grouper 116Coral nurseries 165Coral predating snail 159Corallimorpharian Anemone 29 72Corallivorous snail 159Cowries 76 164Crab Carried Anemone 71Crocodilefish133Crown-of-thorn sea star 92 159Cubefish148Cup coral 49CushionAnemone123Cushionseastar93Cuttlefish84Damselfish31122123126Devilscorpionfish114Domino dascyllus 122Dorid slug 80Double-spined urchin 94 95Dragonfish112Eagle ray 105Egyptian pearl oyster 82Eightline wrasse 124Eilat tubeworm 74 75Electric ray 105Elephant-ear coral 49Emperorangelfish121Encrusting corals 46 65Eyebargoby137False killer whale 155Fancorals67131Feather-stars 90 99Filefish147Finger leather coral Fingeredsoft-coral30Firecoral134Fire sponge 22Fire urchin 95Fissured sand dollar 95Fiveline cardinal 142Flashlightfish174Flatfish132Flat worms 74 75Flower pot coral 59Foliaceous corals 49Footballerdamselfish122Fourlined cleaner wrasse 126Freckledanglerfish152Frog snail 76 164Frogfish152Galaxy coral 46Garden eels 108 109Geometric urchin 95Ghostfish46111Giantclams83172Giant salp 101Gilthead bream 141Goatfish130153Gobies136137Goldies113117145175Goldstripedcardinalfish135Gorgoniancorals1366

Gracefulgoby136Green algae 20 21Green broccoli coral 62GreenChromis31122123145153Green sea turtle 154Greenish synapta 97Grey moray 108Grey rope cucumber 97Greysponge23Groupers 116Harlequin shrimp 92Hawkbill sea turtle 154Hawkfish131Heart urchin 95Heavybeakparrotfish128129Helmet shell 76 95 164Hemisphere corals 42Hermatypiccorals53hermit crab 16 70 88Hickson’sFancoral1367Highfinblenny135Hog wrasse 124Honeycombfilefish147Horn coral 50Hound shark 104Hydroids 24Indian tubeworm 74Jellyfishpolyp22Juvenile coral colonies 47Klunzinger’s wrasse 102, 124Krill 104Laminar corals 52Lanceblenny134Land hermit crab 164Large tube snails 78Leapingblenny135Leather Anemone 17 70Leather coral 60Leatherjacket147Leopardflounder132Lettuce coral 49 51Limpet 10 76LinedButterflyfish118119Lionfish113114179Lizardfish127133153Lobed coral 45 179Lobsters 88Longspine urchin 16 94 125LongnoseHawkfish57131LongspinePorcupinefish149Lunartail grouper 116Maculate Terebra 164Mako shark 18, 104 Mangrove prawn 10Manta ray 18, 106Marble shrimp 88Marbled snake eel 109Marine worms 74Maskedbutterflyfish118Masked puffer 150Massive corals 42Microatolls 58Mimicblenny134Mimic octopus 87Miry’s damsel 145Moon Coral 42

MoonJellyfish26Moon shell 79Moray eels 108Mosessole132Multibarpipefish111Mushroomcorals39Mutable conch 164Mysid 72Spotted dolphin 155Needlefish126Net Fire-coral 25Nettlejellyfish27Noble sea cucumber 96Nudibranchs 80Octocorals 28 60 - 66Octopuses 76 84-86Open Sea life 19Opercleless tubesnail 78Opisthobranch snails 80Orangesponge23Orangespineunicornfish139Orchiddottyback137Organ pipe Coral 68Organ pipe sponge 14Ornatepipefish111Pajamaslug22178Pallid broccoli coral 64Paper nautilus 85Parrotfish102128129174Partner shrimps 127Pearl oyster 82Pearlseastar93Pearl toby 151Pearlfish96Periwinkle 11Pigmyseastar9293Pigmy sweeper 107 144 Pipefish110111Pixyhawkfish131Plate coral 47 49 179Plate Fire-coral 25 29Plate-like corals 52Polished Nerita 10Porcupinefish149Pram bug Amphipod 101Prawns 88Prostrate soft corals 161Pufferfish150Pulsating soft corals 61Rabbitfish140Rays 105Razorfish153Red algae 21Redandvioletbroccolicoral63Red keyhole sponge 22RedSeabannerfish163Red Sea bottlenose dolphin 155RedSeagoatfish130Red Sea minipuffer 151RedSeapicassofish148Red Sea roving grouper 116Redmouth grouper 107 116Reef brittle star 98Reef feather star 99Rockskipper134Rope cucumber 97

Royalangelfish121Royaldamselfish122Rustyparrotfish156Sabretoothedblenny134135Sailfintang139Salps (tunicates) 101Sand dollar 91 95Sand penshell 82Sandalcoral39Scribbledleatherjacket147Scyphozoa 26SeaAnemones70-73127161Sea breams 141Sea cucumber 90 96 97 127Sea harp 164Sea horse 110 111Sea Pen 69sea slugs 76 80Sea squirts 89 100Sea stars 17 90-92Sea turtles 154Sea urchins 90 94 95Seagrass 16Seagrassghostfish111Sergeantmajors122Sharpmushroomcoral39Shell octopus 86Shield slug 80Shore brittle star 11Shorecrab 11Shortbodiedblenny134Shortfinlionfish114Shortspine velvet urchin 94 158Shrimpgobies136Shrimpfish110Siphonophora 24Skates and rays 105 106Slate pencil urchin 95Snake eel 102 108 109Snowflakemoray108Soapfish137Social ascidian 100Soft corals 28 29 54 60-66Sohalsurgeonfish138Solitarycorals38Spanish dancer 81Speckled brittle star 98Speckledsandperch102137Spider conch 77Spindle snails 79Spinecheek130137Spiny Murex 164Sponge carrier 89Spotfinanglerfish152Spottail wrasse 124 126Spotted snake eel 109Squaretailrabbitfish140Squat cleaner shrimp 71 127Squid 76 84Squirrelfish142Staghorn coral 40 46 47Stellate puffer 150Stellaterabbitfish140Sticky sea cucumber 97Sting ray 105Stingfish115Stonefish114115

Stonycorals1329-52StripedButterflyfish118145Striped Engina 77Stripedgoldfish117Striped tubeworm 75Subtidal brittle star 98Suckerfish106Sulphurdamselfish122Sunray Anemone 70Surgeonfish138139Sweepers 144Swimmingclam83Tenlined urchin 95Thicklip wrasse 124Thornbacktrunkfish148Thorny seahorse 110Threadfinbutterflyfish118119159TigerAnemone73Tigercardinalfish135Tigertail sea cucumber 96Tobies 151Top shell 76Tree Black-coral 56Tree-coral 65Triggerfish148Triton trumpet 92Trunkfish148Trush cowrie 164Tube Anemone 72Tubesponge2398Tube worm 75Tubercle coral 46Tubercle sea cucumber 96Tunicate 175Turban snail 76Twobar bream 141Unicornfish139Upside-downJellyfish26Variable “hybrids” 50 51Variable coral crab 89Waving hand coral 64Whale shark 18 19 104Whales 155Whelk 10 79White Banded cleaner shrimp 127White spotted octopus 85White-edgedsoldierfish142158Worms 74 75WrapperSea-Anemones73Wrasses 91 124-126Yellowspottedburrfish149Yellowbarangelfish120Yellowearangelfish121Yellowfacesoapfish137Yellowmargin moray 108Yellowmargintriggerfish148Yellowmouthed moray 127Yellowtailtang139Yellowtail wrasse 124Zebra moray 108

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Photo Credits The book contains 560 photographs, generously donated by the following photographers, most of them members of the “Tapuz” divers’ forum*

Pagesphotographers*81 , 110 , 111 , 125 , 144, 147 , 152Aharoni Ygal155Armosa Omer 19,31,36,55,57,67,73,86,88,89,99,107126,179Ben-Tov Ilan 88Biran Ronen 7Chen Mori 38Cohen Razi26,39,55,59,75,149Colorni Angelo 14,31,54,71,117,171Dafni Lior90 , 92 , 121Diamant Ariel 101Esh Yahav104Grinfeld Javier 81 , 85Gur Amir108,127,139Halevi Elad104Kendler Assaf 117 , 124Koslevski Robert 27,57,71,83,92Lederman Oren 89,140,193Levi Bader 97 , 115Levi Keren118Lynn Anat118Meidn Eldan109 , 124Movshowitz Ziv176Pinchover Liron 89Poupin J. 12Schuhmacher H. 40 , 165 , 166ShafirShai101Shpigel muki 85Shshar Nadav127,136Stern Amir18,72,93,97,111,113,137,139,149Tamir Ben33 ,37,86,89,126,135,147Weinberg Danny

*All other pictures were taken by Jacob Dafni and Michael Levin** Throughout the book, the credits are arranged according to the order of the pictures from the

upper left, and in a clockwise direction.