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

5

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

6

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

7

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

8

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

9

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.

13

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

14

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

15

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

16

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

17

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

18

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

19

Green Sea Turtle Nesting Sites

20

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

21

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

22

Hawksbill Description

• Carapace is yellow, brown, or orange

• Carapace length is 2.5 to 3 ft

• Weigh between 100 and 150 lbs

Claudia Townsend

23

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

24

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

26

Hawksbill Nesting Sites

27

Hawksbill Status and Threats

• United States: Endangered

• International: Critically Endangered

• Harvest for their shell is greatest threat

• Estimated population: 22,900 nesting females

28

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

29

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

30

Leatherback Diet

• Have very delicate jaws

• Papillae help to trap food

• Feed almost exclusively on jellyfish

Karumbe

31

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

32

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

33

Leatherback Nesting Sites

34

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

35

Loggerhead

• Caretta caretta• Named for its very

large head• Carapace has large

non-overlapping scutes• Carapace is heart

shaped• Five lateral scutes

36

Loggerhead description

• Carapace is reddish-brown in color

• Carapace length is 2.5 to 3.5 ft

• Weigh up to 350 lbs

Alan Rees

37

Loggerhead Diet

• Strong jaws allow it to crush animals with shells

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

Alejandro Fallabrino

38

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

39

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

40

Loggerhead Nesting Sites

41

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

42

Hector Barrios-Garrido

Sea Turtle Fishery Threats

Hector Barrios-Garrido

Janice BlumenthalMichael Coyne

Trawling

43

Sea Turtle Pollution Threats

Lucia Guillen

Robson G. Santos

Robson G. Santos

Tar

44

Habitat Degradation

Kate Mansfield

Beach Renourishment

Lights

Moustakas Vasilios

Development on Beach

45

Sea Turtle Predation

Alexander Gaos

Alejandro Fallabrino

Robson G. SantosRats

Dogs

Zoe Bass

Shark

46

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>