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.
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
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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
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
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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
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
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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
26
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
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
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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
33
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>