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Marine Reptiles

Marine Reptiles

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Marine Reptiles

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  1. 021 Marine Reptiles

  2. Phylum Chordata • Subphylum Vertebrata • 3 Classes: • Class Reptilia • Class Aves (birds) • Class Mammalia

  3. Reptiles, Birds, Mammals • Evolved from fish-like vertebrates • Moved from the water to the land • Developed 2 pairs of limbs for walking – tetrapods • Developed lungs to breathe • Challenge of land - need to avoid drying out

  4. Lungfish – A Missing Link • Class Osteichthyes • Subclass Sarcopterygii (lobe-finned) • Breathe air through swim bladder • Pectoral and pelvic fins → “legs”

  5. What About Amphibians? • Lungfish – now only freshwater • Amphibians – some tolerate brackish water, none strictly marine • Extinct amphibians - ancestors to the reptiles • Extinct reptiles – • ancestors to the birds

  6. Reptiles • Better adapted to life on land than amphibians • Skin covered with scales, prevents water loss • Eggs – leathery shell, lay on land

  7. Marine Reptiles Some reinvaded the oceans, but still breathe air: • Turtles (Order Chelonia) • Snakes (Order Squamata) • Iguanas (Order Squamata) • Crocodiles (Order Crocodilia) Saltwater crocodile Marine turtle Sea snake Marine iguana

  8. Marine Reptiles • Ectotherms (“cold-blooded”), so mostly in warmer waters, seasonal in temperate waters • Cold stunning – • Turtles too far north when water temperature suddenly drops (<50°F) • Get lethargic, immobile, float to surface, wash up on beach • Fatal if not warmed

  9. Marine Turtles (Honu)

  10. History • Found in fossil record200 mya(Triassic) • Common in Cretaceous(130 mya) • Present day genera originated60(Eocene)and10 mya(Pleistocene) • Not a very diverse group • Mostly tropical and subtropical

  11. Taxonomy Class Reptilia Order Chelonia- warm to temperate and boreal seas ex. leatherback, ridley's, kemps Order Chelonia- F. Cheloniidae- green, flatback, hawksbill, loggerhead F. Dermochelidae- leatherback reduced shell, dermal bone scutes compose shell F. Emydidae- diamond back terrapin Hawaii species- green, hawksbill, leatherback, Olive Ridley

  12. Anatomy • Dorsal shell = carapace • Ventral shell = plastron • Head does not retract carapace plastron

  13. Anatomy Female Male

  14. Adaptation to salt water Lacrimal glands

  15. Green turtle Scientific Name: Chelonia mydas Diet: seagrass and algae Size: ~500lbs Conservation Status: threatened Habitat: high energy ocean beaches, convergence zones in the pelagic habitat, benthic feeding grounds in relatively protected waters Range: throughout world in all tropical and subtropical oceans

  16. Kemp’s Ridley Scientific Name:Lepidochelys kempii Diet: mollusks, crustaceans, jellyfish, fish, algae or seaweed, and sea urchins. Size: 100lbs Conservation Status: highly endangered Habitat: shallow water benthic feeder Range: Gulf of Mexico, Texas

  17. Olive Ridley Scientific Name:Lepidochelys olivacea Diet: jellyfish, tunicates, sea urchins, bryozoans, bivalves, snails, shrimp, crabs, rock lobsters, and sipunculid worms Size: >100lbs Conservation Status: highly endangered Habitat: shallow marine waters Range: Indo-Pacific, S. Atlantic NOAA NOAA

  18. Hawksbill Scientific Name:Eretmochelys imbricata Diet: Shellfish Size: 76 - 91 cm (30 - 36 in) Conservation Status: Endangered Habitat: coral reefs, rocky coasts Range: Tropical Atlantic, Pacific and Indian Oceans; Caribbean

  19. Loggerhead Scientific Name:Caretta caretta Diet: Crustaceans Size: 76 - 102 cm (30 - 40 in), 300 lbs Conservation Status: Vulnerable Habitat: coasts, open sea Range: Temperate and tropical areas of the Pacific, Indian and Atlantic Oceans NOAA

  20. Flatback Scientific Name: Natator depressus Diet: sea cucumbers, soft corals, jellyfish Size: < 1 m in length, 200 lbs Conservation Status: vunerable Habitat: near continental shelf, shallow, soft bottom sea beds Range: northern part of Australia

  21. Leatherback Family: Dermochelidae: Scientific Name: Dermochelys coriacea Diet: sea jellies and salps Size: 1500 lbs Conservation Status: endangered Habitat: pelagic water Range: tropical seas, oceanic islands, Atlantic, Pacific, & Indian Ocean

  22. Reproduction Mating- at sea Migration- occurs in late spring; female is accompanied by male Green sea turtles migrate as far as 800 miles from feeding area to nest in Northwestern Hawaiian Islands Egg laying behavior- return to same beach (natal beach)

  23. Kemps Ridley nesting • Usually nest at night • Front flippers dig pit, rear flippers carve out burrow

  24. Egg tooth- used to chip away at shell Group effort to get out of nest- emerge at night (safer) and head towards brightest light Artificial lights- confuse hatchlings Turtle nest Cross section

  25. Leatherback hatching Kemps Ridley hatchlings Clutch size- about 100 eggs & covers pit with sand Egg incubation- 2 months depending upon species Sex determined by temperature- males lower temp, females higher temp

  26. Predators

  27. Factors Affecting Green Sea Turtle Population Hawaii- 100-350 nesting females French Frigate Shoals in the Northwest Hawaiian chain • Hunters • Fisheries • Marine Debris • Coastal Development and Habitat Degradation • Fibropapilloma

  28. Commercial Value • Meat • Eggs- nearly forbidden in all countries with nesting beaches • Soup • Jewelry • Leather Convention on International Trade in Endangered Species (CITES): turtle commerce prohibited in countries that signed agreement

  29. Protection and Management Law enforcement- in Hawaii, turtles protected under Endangered Species Act • Riding or harassing- $100,000 fine + prison time • Bringing turtle products into Hawaii- $20,000 + prison time

  30. Protection and Management Increase sea turtle populations: • Ranching- eggs or hatchlings from wild populations • Farming- originally from wild populations, for breeding stock

  31. Protection and Management Fishing regulations- • Shrimp Trawlers - incidental catch by commercial shrimp fish nets: drowned 10,000 turtles each year • Drift nets, gill nets • Turtle Excluder Device (TED)

  32. Turtle Excluder Device

  33. Incidental Marine Turtle Catches

  34. Marine Debris- plastic bags, soda can plastic rings, fishing line, oil and tar Costal development and habitat degradation-noise, light, beach obstructions- affect nesting habitat

  35. Fibropapilloma- virus in Green turtles • Affects ability to feed, see, move about, or breath • May be due to pollutants, blood parasites, or habitat change • Kaneohe Bay (1991)- >50% infected

  36. Sea Snakes Yellow- bellied sea snake

  37. Sea Snakes • Diversity: • Laticodtidae- krates- 5 species (1 is fw in Solomon Islands) • Hydrophidae- 54 different species • All derived from Colubrid ancestor; colubrids evolved 40 mya; Laticotids evolved from colubrids 30 mya • Location: • Laticotids- live from east coast India to Japan and come to the tip of Cape York (Australia) • Hydrophiids- found from south tip of Africa to India to South East Asian Islands to Japan to north half of Australia • Habitat: • Primarily tropical; coastalestuaries, coral reefs, open sea; 33-36oC

  38. Sea Snakes • Behavior: Often schooling in aggregations; Not aggressive but human fatalities have occurred • Prey: Feed on small fish or squid, which are killed with powerful venom • Predators (few): sharks, snapper, grouper, crabs, saltwater crocodiles, raptors; they descend to escape • Venom: 2-10 times as toxic as that of a cobras

  39. Sea Snakes • Adaptations to life in the sea • Osmoregulation: skin is impermeable to salts; salts eliminated by sublingual gland • Developing a flattened paddle-shaped tail and a laterally compressed body. • Reduced metabolic rate and increased tolerance for low oxygen levels • Lungs- greatly enlarged; hydrostatic organ • Gaseous exchange - lungs and the skin.

  40. Sea Snakes • Reproduction: • Krates are oviparous and lay eggs on land • Hydrophiids are viviparous and produce young in the water • Not much known about breeding • However, olive sea snake breed in spring; seasonal courtship displays Banded sea krates forming mating group Olive Sea Snake

  41. Saltwater crocodiles • Largest living crocodilians: 6-7 m long • Eggs laid and incubated on land • Tropical and subtropical

  42. Marine Iguanas • Endemic to Galapagos islands • Herbivorous: graze on seaweeds • Salt-glands on nose to eliminate excess salt • Recently observed feeding on land for first time • They return to land to escape predators.

  43. Inquiry • What is a natal beach? • What advantage is there in turtle hatchlings leaving in a group rather than individually? • Are the consequences for harassing a turtle adequate? • How does the fibropapilloma virus effect green sea turtles? • What is a TED? How do marine turtles regulate salt in their body?