Overview On Sea Turtles
- 1. Overview on Sea Turtles By Matthew Davis MAR 490
- 2. Purpose • Genealogy of the modern sea turtles • Descriptions of different species • Breeding habits • Conservation methods
- 3. Ancestry • 1st turtles appeared about 220 million years ago • 1st sea turtles appeared in the fossil record around 90 million years ago o Archelon shell length up to 2 meters long
- 5. Modern Sea Turtles • The 7 species are found in two families o Dermochelyidae : Leatherback o Chelonidae: 6 hard shelled sea turtles
- 6. Leatherback Sea Turtle • Dermochelys coriacea o Largest of the living sea turtles o 500 lbs to 1000 lbs o No bony shell instead shell is leathery o Feed mainly on invertebrates (e.g. jellyfish) in deep ocean waters o Only turtle to migrate to cold waters of the North Atlantic
- 8. Hawksbill Sea Turtle • Eretmochelys imbricata o Named for the its hawk-like beak o Typical size is 130 lbs o Feeds on invertebrates found mostly on coral reefs o Famous for its shell
- 10. Loggerhead Sea Turtle • Caretta caretta o Named for typically large head o 300 lbs to 900 lbs o Most common seen sea turtle around Gulf Coast
- 11. Caretta caretta
- 12. Kemp’s Ridley Sea Turtle • Lepidochelys kempi o 70 to 100 lbs o Only sea turtle that nests during the day All the Kemp’s Ridley turtles nest at one beach in one night Known as an “arribadas” Famous film from 1947 known as the Herrera film shows this mass nesting at Rancho Nuevo, Mexico Up to 40,000 turtles will nest on one beach
- 14. Green Sea Turtle • Chelonia mydas o Named for the green soup that was made from their meat o 350 to 550 lbs but can reach 800 lbs o Heavily poached for its meat and fat o Feed mainly on algae and sargassum
- 15. Chelonia mydas
- 16. Olive Ridley Sea Turtle • Lepidochelys olivacea o Normally 70 to 90 lbs o Found in tropical and subtropical waters o Nest in arribadas but during the night Some arribadas will consist of 10,000 or more turtles
- 18. Flatback Sea Turtle • Natator depressus o Typically weigh about 160 lbs o Grayish to greenish in coloration o Found only the waters surrounding Australia
- 20. Breeding Habitats • Typically nesting is done at night • Can lay up to a 100 eggs in a clutch o Eggs roughly the size of a ping-pong ball • Young have temperature-dependent sex determination o Incubation temperature determines sex of young • Typically 60 days to hatch
- 23. Conservation • Most species are on the verge of extinction • Main factors in population decline are: o Direct harvesting for meat and byproducts o Incidental capture by fishermen o Loss or alteration of nesting beaches o Increased pollution and disease Fibropapilloma virus
- 24. What’s being done? • The use of TEDs as law for shrimping industry • Modified fishing gear • Proactive measures done by local communities