13-1 chapter 13 phylum cnidaria. copyright © the mcgraw-hill companies, inc. permission required...

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CHAPTER 13CHAPTER 13CHAPTER 13CHAPTER 13

Phylum CnidariaPhylum CnidariaPhylum CnidariaPhylum Cnidaria

Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.

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Phylum Cnidaria

Fossil specimensFossil specimens dated to over dated to over 700 million 700 million years agoyears ago

General Characteristics Soft bodied Carnivorous Stinging tentacles Examples: Jellyfish, sea anemones


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Phylum CnidariaPhylum Cnidaria

Classes of CnidariaClasses of Cnidaria Hydrozoa (Portuguese Man-of-War, Hydra)Hydrozoa (Portuguese Man-of-War, Hydra) Scyphozoa (True Jellyfish - Aurelia)Scyphozoa (True Jellyfish - Aurelia) Anthozoa (Sea Anenome, Corals)Anthozoa (Sea Anenome, Corals)


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Characteristics of Phylum Cnidaria Characteristics of Phylum Cnidaria All areAll are aquatic aquatic and mostly marine and mostly marine SymmetrySymmetry

RadialRadial Two body typesTwo body types

Free-swimming medusa Free-swimming medusa Sessile polypsSessile polyps

Acoelomates - No coelomAcoelomates - No coelom Diploblastic Diploblastic Blind (Incomplete) GutBlind (Incomplete) Gut


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Tentacles Tentacles usually encircle mouth or oral regionusually encircle mouth or oral region Equipped with specialized cells: Equipped with specialized cells: cnidocytes cnidocytes

CnidocytesCnidocytes: stinging cells located on their tentacles: stinging cells located on their tentacles NematocystNematocyst: : stinging organelle, poison-filled structure that stinging organelle, poison-filled structure that

contains a tightly coiled dart.contains a tightly coiled dart. Tactile stimulation of Tactile stimulation of cnidocilcnidocil, causes nematocyst to discharge, causes nematocyst to discharge After discharge, cnidocyte is absorbed and another developsAfter discharge, cnidocyte is absorbed and another develops

Mechanism of Nematocyst Discharge Mechanism of Nematocyst Discharge When stimulated, water rushes into the capsuleWhen stimulated, water rushes into the capsule The operculum (cap) opens and rapidly launches the filamentThe operculum (cap) opens and rapidly launches the filament Barbs Barbs inject poisoninject poison into prey into prey Only a Only a few jellyfish - and the Portuguese man-of-warfew jellyfish - and the Portuguese man-of-war can seriously can seriously

harm humansharm humans


Cnidarian Phyla

Topical Solutions if stung: Topical Solutions if stung: acidic (vinegar) acidic (vinegar) Urine - only if urine is acidic?? Most urine is sterile.Urine - only if urine is acidic?? Most urine is sterile.Apply heat or ice for pain (also denatures toxins)Apply heat or ice for pain (also denatures toxins)Salt water should be applied to remove any excess toxins.Salt water should be applied to remove any excess toxins.


Discharged cnidae

recoiled


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OTHER CNIDARIAN CHARACTERISTICSOTHER CNIDARIAN CHARACTERISTICS Sense organsSense organs for balance ( for balance (statocystsstatocysts) and ) and

photosensitivity (photosensitivity (ocelliocelli)) Nerve net Nerve net

Simple nervous system, no brainSimple nervous system, no brain Asexual reproductionAsexual reproduction

Budding in polypsBudding in polyps Sexual reproduction Sexual reproduction

By gametes in all medusa and some polypsBy gametes in all medusa and some polyps Monoecious or DioeciousMonoecious or Dioecious

No No excretory or respiratory systemexcretory or respiratory system


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Life CyclesLife Cycles Typically, zygote develops into a motile Typically, zygote develops into a motile planula larvaplanula larva Planula settles, and metamorphoses into a Planula settles, and metamorphoses into a polyppolyp

Produce other polyps asexuallyProduce other polyps asexually Polyps eventually produce a free-swimming Polyps eventually produce a free-swimming

medusa by asexual reproduction medusa by asexual reproduction (Budding)(Budding)


HydrazoanLife Cycle


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A. Hermit crab uses cnidarian as protectionB. Showing growth on host shell


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Form and Function Form and Function Cnidaria have two basic body plans: Cnidaria have two basic body plans:

polyp and medusapolyp and medusa Polyp Polyp

Adaptation to a sedentary lifeAdaptation to a sedentary life Tubular body with the mouth directed upward Tubular body with the mouth directed upward

and surrounded by tentaclesand surrounded by tentacles Mouth leads into a Mouth leads into a blind-gutblind-gut cavity cavity Reproduce asexually by budding, fission, or Reproduce asexually by budding, fission, or

pedal lacerationpedal laceration


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Phylum Cnidaria - MedusaPhylum Cnidaria - Medusa MedusaMedusa

Bell or umbrella-shapedBell or umbrella-shaped Usually free-swimmingUsually free-swimming Mouth directed downward Mouth directed downward Tentacles may extend down from rim of Tentacles may extend down from rim of

umbrellaumbrella


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Body WallBody Wall Cnidarian bodyCnidarian body

Outer Outer epidermisepidermis Inner Inner gastrodermisgastrodermis (gastrovascular cavity = gut) (gastrovascular cavity = gut) Layers separated by Layers separated by mesogleamesoglea Mesoglea Mesoglea

Gelatinous (at least 95% water) - jellylikeGelatinous (at least 95% water) - jellylike Continuous, extending through body and Continuous, extending through body and

tentaclestentacles Supports bodySupports body Thickness variesThickness varies


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Class HydrozoaClass Hydrozoa Most marine and colonial with both polyp and Most marine and colonial with both polyp and

medusa forms (polyp form dominates)medusa forms (polyp form dominates) ColonialColonial Obelia Obelia

Typical hydroid has a Typical hydroid has a base, a stalkbase, a stalk, and one or , and one or more individual polyp animalsmore individual polyp animals

Feeding polypsFeeding polyps with tentacles around mouth= with tentacles around mouth= hydranthshydranths

In Obelia, the medusa buds are formed by a In Obelia, the medusa buds are formed by a reproductive polypreproductive polyp called a called a gonangiumgonangium


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Obelia Life Cycle


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Hydroids


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Bell medusa(Hydroid)


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Medusa

D. Developing Polyp from Planula: Frustule = bud


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Freshwater Hydrozoan


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Class Hydrozoa: AnimalsClass Hydrozoa: Animals HydraHydra

Found in Found in fresh waterfresh water Worldwide distributionWorldwide distribution (16 species in North America) (16 species in North America) Polyp body formPolyp body form Ring of 6–10 hollowRing of 6–10 hollow tentacles tentacles encircles mouth encircles mouth

Portuguese Man-of-WarPortuguese Man-of-War Floats on surface (air bladder)Floats on surface (air bladder) Tentacles reach up to 10 metersTentacles reach up to 10 meters Contains polyp colonies and medusaContains polyp colonies and medusa Air bladder contains gases releasedAir bladder contains gases released


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Hydra catching a water flea


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Hydra w/ developing bud and ovary/egg


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Portuguese man-of-war ColonySecrete powerful neurotoxin - Class Hydrozoa (Many Polyps and medusa in colony)


Differences between Hydrozoa and Scyphozoa

Hydrozoa Colonial Stages Mostly Polyp life form Medusa, if present, are

usually small Small amounts of mesoglea Less tentacles

Scyphozoa Large Medusa forms Cells present in mesoglea More complex More tentacles Large amount of mesoglea


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Class ScyphozoaClass Scyphozoa Most of the Most of the larger jellyfisheslarger jellyfishes belong to this belong to this

classclass Nearly all Nearly all float in open seafloat in open sea Bells vary in shape and sizeBells vary in shape and size

Composed mostly of Composed mostly of mesoglea mesoglea


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Class Scyphozoa

Giant jellyfish-exceeds 2 Meters in diameter


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Moon Jellyfish(Aurelia)


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Phylum Cnidaria - ScyphozoaPhylum Cnidaria - Scyphozoa

Reproduction methodsReproduction methods Asexual - Similar to other cnidarians. BuddingAsexual - Similar to other cnidarians. Budding But also use But also use StrobilationStrobilation - asexual budding of - asexual budding of

saucerlike buds that develop into medusa.saucerlike buds that develop into medusa.


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Life Cycle of Aurelia, marine scyphozoan

Strobilation


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Class AnthozoaClass Anthozoa Lack a medusa stageLack a medusa stage All marine,All marine, in both deep and shallow water, in both deep and shallow water,

and vary in sizeand vary in size Examples: sea anemones, sea coralsExamples: sea anemones, sea corals


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Sea Anemones


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Structure of Sea Anemone


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Phylum Cnidaria - AnthozoaPhylum Cnidaria - Anthozoa

Sea AnemonesSea Anemones Polyps larger and heavier than hydrozoan Polyps larger and heavier than hydrozoan

polypspolyps Attach to shells, rocks, timber, etc. by pedal Attach to shells, rocks, timber, etc. by pedal

discsdiscs Crown of tentacles surrounds the flat oral Crown of tentacles surrounds the flat oral

discdisc

When in danger,When in danger, water rapidly expelled through water rapidly expelled through pores as the anemone contracts to a small sizepores as the anemone contracts to a small size


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Sea Anemone being attacked by a Sea Star

Can Sea Anemones run?


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Tube Anemone


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Phylum Cnidaria - AnthozoaPhylum Cnidaria - Anthozoa

Reproduction of Sea AnemonesReproduction of Sea Anemones Some Some dioecious,dioecious, some some monoeciousmonoecious Monoecious species - Monoecious species - produce sperm first and produce sperm first and

eggs latereggs later Fertilization is external or in gastrovascular Fertilization is external or in gastrovascular

cavitycavity Zygote becomes a Zygote becomes a ciliated larvaciliated larva Pedal laceration, small pieces of pedal disc Pedal laceration, small pieces of pedal disc

break off and regenerate a small anemonebreak off and regenerate a small anemone Budding can occur Budding can occur


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Closed during day, open to feed at night


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Polyp ofCoral


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A Thorny Coral


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A soft coral on Pacific Coral Reef


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Sea Fan Red Whip CoralRed Gorgonian

Horny Coral Types


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Coral ReefsCoral Reefs Great diversityGreat diversity of organisms (under rainforest) of organisms (under rainforest) Plants and animals are limited to top layer Plants and animals are limited to top layer

Above the calcium carbonate depositsAbove the calcium carbonate deposits Reef forming corals and algaeReef forming corals and algae precipitate calcium precipitate calcium

carbonatecarbonate to form most coral reefs to form most coral reefs Require warmth, light, and salinity of undiluted Require warmth, light, and salinity of undiluted

sea water (contains calcium)sea water (contains calcium) Photosynthetic zooxanthellaePhotosynthetic zooxanthellae live in their tissues live in their tissues Provide food for corals, carbon for calcium Provide food for corals, carbon for calcium

carbonate, and recycle phosphorus and carbonate, and recycle phosphorus and nitrogenous wastesnitrogenous wastes


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Phylum Cnidaria - Human ImpactPhylum Cnidaria - Human Impact

Nutrients from fertilizer and sewage threaten coral Nutrients from fertilizer and sewage threaten coral reefs with excessive algal growth - or by killing reefs with excessive algal growth - or by killing zooxanthellae, which leads to coral bleaching.zooxanthellae, which leads to coral bleaching.

Persian Gulf reefs have withstood surprising Persian Gulf reefs have withstood surprising amounts of oil pollutionamounts of oil pollution

Coral reefs in many areas are threatened by factors Coral reefs in many areas are threatened by factors mostly of human originmostly of human origin

HUMAN IMPACT:

13-1 chapter 13 phylum cnidaria. copyright © the mcgraw-hill companies, inc. permission required...

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