caroline rogers sea turtles. 2 introduction air breathing reptiles inhabit temperate to tropical...

Sea Turtles

2

Introduction

• Air breathing reptiles

• Inhabit temperate to tropical seas

• Range in size from less than 100lbs (olive ridley) to 1300lbs (leatherback)

• Shell consists of carapace (upper portion) and plastron (lower portion)

• No teeth but have beak like jaws

3

Introduction

• No external ears but have skin covered eardrums

• Good vision in water• Excellent sense of smell• Earliest sea turtle fossil 150 million

yrs old• 100+ yrs ago they traveled the sea

in great numbers (too many to count)

• Habitat destruction and demand for their meat, eggs, leather, and shells has caused population destruction.

Dubose Griffin

4

Growth

• Theorized that baby turtles spend their time in sargassum mats

• Move to adult feeding grounds when they reach dinner plate size

• 15 to 50 years to reach sexual maturity

• Thought that some can live over 100 yrs

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Behavior

• Generally solitary

• Feed during the day

• Can sleep on surface or on the bottom

• Males very rarely return to land

• Females return to land only to nest

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Mating

• Mate prior to female nesting emergence

• Males court a female by nuzzling the head, biting the neck, and/or biting the rear flippers

• If female receptive the male latches on with front claws and does the nasty

• Females may mate with several males before laying her eggs

• Egg clutches may be fertilized by several males

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Nesting

• Females return to natal beach to nest

• Often emerge a few yards from their last nesting site

• Usually at night• After finding suitable dry

sand she digs a nest with her flippers

• Eggs are flexible and covered in mucus

Mathew Godfrey

Adhith Swaminathan

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Nesting

• Female fills in hole and disguises the nest by flinging sand everywhere

• When done she crawls back to the water

• Nesting season in U.S. is April through October

Abdulmaula Hamza

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Incubation

• The hotter the temperature the faster the eggs will develop

• Warmer temperatures will result in more females

• Cooler temperatures will result in more males

• Vulnerable to predation from digging animals and humans

Kate Mansfield

10

Mathew Godfrey

Kellie Pendoley

Emergence

• Babies us “caruncle” (egg tooth) to break open shell

• Dig out of nest as a group• Emerge during cooler

temps (night or during rain)• Move to brightest horizon

(hopefully ocean not lights)• Many predators on beach:

birds, crabs

11

Hatchlings

• Swim out to sea to find seaweed mats

• May live in the mats for years

• Many predators: birds, sharks, fish

• Only one in 1,000 survive

Mary Wozny

12

Navigation

• How do sea turtles migrate 100 to 1000 miles and find their way back to their natal beach?

• They do not see well out of water so landmarks is unlikely

• Theory: They are able to detect the intensity and angle of the earths magnetic field.

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Sea Turtle Species

• Green sea turtle (Chelonia mydas)

• Hawksbill (Eretmochelys imbricata)

• Leatherback (Dermochelys coriacea)

• Loggerhead (Caretta caretta)

Robert von Dam

Douglas Shea

Matthew Godfrey

Marco Affronte

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Green Sea Turtle

• Chelonia mydas• Named for green colored fat

under its shell• Single pair of prefrontal

scales (scales in front of eyes)

• Small head• Carapace is bony with non-

overlapping scutes• Four lateral scutes• Body nearly oval

4 nonoverlapping lateral scutes

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Green Sea Turtle Description

• Variable shell colorations

• Carapace length is 3.5 to 4 ft

• Weigh between 300 and 400 lbs

• Largest ever recorded was 5 ft and weighed 871 lbs

Kevin Moses

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Green Sea Turtle Diet

• Changes throughout life

• Less than 8-10 inches: worms, crustaceans, sea grasses, and algae

• 8-10 inches and larger: sea grasses and algae

• Only sea turtle that is herbivorous as an adult

Caroline Ridgers

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Green Sea Turtle Habitat

• Near coastlines and bays

• Areas with sea grass beds

• Rarely seen in open ocean

• Found in all temperate and tropical waters Robert von Dam

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Green Sea Turtle Nesting

• Nest at two or more year intervals

• Nest three to five times per season

• Lay ~115 eggs per nest

• Eggs hatch after ~60 days

Mary Wozny

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Green Sea Turtle Nesting Sites

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Green Sea Turtle Status and Threats

• United States: Endangered• International: Endangered• Greatest threat is from commercial harvest for

eggs and food.• Used for leather and small ones stuffed for

souvenirs• Commercial trawling increasing threat• Estimated population: 88,520 nesting females

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Hawksbill

• Eretmochelys imbricata• Named for hawk-like beak• Smaller sea turtle • Head small with two pairs of

prefrontal scales• Bony carapace with

overlapping scutes• Four lateral scutes• Body elliptical in shape

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Hawksbill Description

• Carapace is yellow, brown, or orange

• Carapace length is 2.5 to 3 ft

• Weigh between 100 and 150 lbs

Claudia Townsend

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Hawksbill Diet

• Narrow head and beak-like jaws enable it to get into narrow cracks and crevices

• Feed on sponges, anemones, squid, and shrimp.

Jason BuccheimJason Buccheim

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Hawksbill Habitat

• Found around coastal reefs and rocky areas.

• Also frequent lagoons and estuaries

• Found in tropical and subtropical waters worldwide (most tropical sea turtle) Michael Coyne

25

Hawksbill Nesting

• Nest at two or more year intervals

• Nest two to four times per season

• Lay ~115 eggs per nest

• Eggs hatch after ~60 days

Johan Chevalier

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Hawksbill Nesting Sites

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Hawksbill Status and Threats

• United States: Endangered

• International: Critically Endangered

• Harvest for their shell is greatest threat

• Estimated population: 22,900 nesting females

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Leatherback

• Dermochelys coriacea• Named for its shell which is

composed of a tough rubbery skin that covers many tiny bony plates

• Carapace is large, elongated, and flexible with seven ridges that run the length of the turtle

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Leatherback Description

• Carapace is black or dark grey with pale spots

• Carapace length is 4 to 6 ft.

• Weigh between 550 and 1,500 lbs

• Largest one ever recorded was almost 10 ft (including head and tail) and weighed 2,019 lbs

Karumbe

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Leatherback Diet

• Have very delicate jaws

• Papillae help to trap food

• Feed almost exclusively on jellyfish

Karumbe

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Leatherback Habitat

• Found primarily in the open ocean

• Known to be active in water down to 40F (only reptile known to be active at such a low temp)

• Most widely distributed sea turtle

• Inhabit oceans worldwide as north as Alaska and as south as South Africa

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Leatherback Nesting

• Nest every one to three years

• Nest six to nine times per season

• Lay ~80 fertilized eggs (30 smaller unfertilized)

• Eggs hatch in ~65 days• May change nesting

beaches but stay in same region

Matthew Godfrey

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Leatherback Nesting Sites

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Leatherback Status and Threats

• United States: Endangered

• International: Critically Endangered

• Incidental commercial harvest and pollution are greatest threats– Pollution such as plastic bags and balloons

are mistaken as jellyfish

• Estimated population: 35,860

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Loggerhead

• Caretta caretta• Named for its very

large head• Carapace has large

non-overlapping scutes• Carapace is heart

shaped• Five lateral scutes

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Loggerhead description

• Carapace is reddish-brown in color

• Carapace length is 2.5 to 3.5 ft

• Weigh up to 350 lbs

Alan Rees

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Loggerhead Diet

• Strong jaws allow it to crush animals with shells

• Feed on clams, muscles, horseshoe crabs, and other invertebrates

Alejandro Fallabrino

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Loggerhead Habitat

• Feed along the continental shelves in the shallow water

• They also feed in estuaries and coastal bays

• They are found in all temperate and tropical waters of the world

Matthew Simonds

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Loggerhead Nesting

• Nest every two or more years

• Nest four to seven times per season

• ~100 to ~126 eggs per nest

• Eggs incubate for ~60 days

Larisa Avens Larisa Avens

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Loggerhead Nesting Sites

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Loggerhead Status and Threats

• United States: Threatened

• International: Endangered

• Loss of nesting habitat due to development is the greatest threat

• Trawling and pollution are other threats

• Estimated population: 44,560

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Hector Barrios-Garrido

Sea Turtle Fishery Threats

Hector Barrios-Garrido

Janice BlumenthalMichael Coyne

Trawling

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Sea Turtle Pollution Threats

Lucia Guillen

Robson G. Santos

Robson G. Santos

Tar

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Habitat Degradation

Kate Mansfield

Beach Renourishment

Lights

Moustakas Vasilios

Development on Beach

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Sea Turtle Predation

Alexander Gaos

Alejandro Fallabrino

Robson G. SantosRats

Dogs

Zoe Bass

Shark

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Resources

• Hillis-Star, Zandy-Marie, Ralf Boulon and Michael Evans. Sea Turtles of the Virgin Islands and Puerto Rico. 25 Oct. 2006. U.S. Geological

Survey Dec. 15, 2006. <http://biology.usgs.gov/s+t/SNT/noframe/cr136.htm>

• Information on Sea Turtles and Threats To Their Survival. 1995. Caribbean Conservation Corporation & Sea Turtle Survival League. 15 Dec. 2006. <http://www.cccturtle.org/sea-turtle-information.php>