Transcript Sea turtles
Marine Reptiles, Birds, and Mammals • ~350 million years ago, terrestrial vertebrates evolved from fish-like vertebrates – Two pairs of fins adapted for walking (“tetrapods”) – Tetrapods have internal air sacs called lungs – First land vertebrates were the amphibians Tetrapod Evolution Marine Amphibians? • Amphibians are thin-skinned animals that require moisture to keep from drying out • “Amphibian” literally translates to “double life” – Larval form uses gills for breathing • There are NO marine amphibians; saltwater would result in rapid desiccation Marine Reptiles, Birds, and Mammals • Having adapted to land, various groups of reptiles, birds and mammals returned to the ocean • Some, like sea turtles and marine birds, have not fully made the transition and return to land to lay eggs • Others spend their entire lives at sea, never returning to land Marine Reptiles • Reptiles are cold-blooded, air-breathing animals with tough, scaly skin • Marine reptiles include: – Sea turtles (7 species) – Sea snakes (55 species) – Marine crocodiles (1) – Marine lizards (iguanas; 1) Marine Reptiles • Like most fish, marine reptiles are ectothermic and poikilothermic; “cold-blooded” • Marine reptiles breath air; they have internal lungs, not gills • Marine reptiles are equipped with special salt glands to concentrate and excrete salts • Leathery shells prevent eggs from drying out Marine Reptiles: Sea Turtles • Sea turtles belong to an ancient group of reptiles • Their body is enclosed by an armor-like shell, or carapace that is fused to their backbone • All are streamlined and adapted for life in the water – Forelimbs are modified into flippers – Hindlimbs act as rudders – Cannot retract head or limbs Marine Reptiles: Sea Turtles Our Local Sea Turtles scienceblogs.com Leatherback Hawksbill http://www.costaricaturtles.com/costa_new_seaturtles.html http://fwie.fw.vt.edu Green www.underwater.com.au Loggerhead www.dnr.state.md.us/ fisheriesoxford/ research/fwh/ seaturtles.html Kemp’s Ridley Marine Reptiles: Sea Turtles • Sea turtles spend their entire lives at sea; only females come ashore to lay eggs – Homing (return to same beach where they were born to lay eggs) http://www.youtube.com/watch?v=UKkScAel52w http://www.conservation.org/great_turtle_race/Pages/main.aspx Temperature-dependent Sex Determination • When female sea turtles come ashore to lay their eggs, the depth of the burrow she digs affects the temperature of the eggs that are laid • Temperature (not genetics) determines the sex of the offspring – Warmer nests females © Aqua Image/age fotostock Got Arribada? • Female sea turtles aggregate on the beach in mass nestings called arribadas http://www.youtube.com/watch?v=W4u3GL9SyyM Save the Sea Turtles! • Most of the world’s sea turtles are threatened or endangered with extinction • Dangers include: – Shrimp trawling; Long-line fishing – Beach destruction, hardening of shorelines, vehicles and dogs on beaches – Bright beach lights – Marine debris; Ghost netting – Global warming Credit: © James Watt/Visuals Unlimited Trends in nesting leatherback turtles in the Pacific Lewison, R., S. Freeman & L.B. Crowder. 2004 Map of Reported Longline Effort, inc. all Tuna & Swordfish for 2000 1.4 Billion Hooks Deployed Every Year Lewison, R., S. Freeman & L.B. Crowder. 2004. Quantifying the effects of fisheries on threatened species: the impact of pelagic longlines on Loggerhead and Leatherback Sea Turtles Swordfish fisheries incidentally catch the majority of Leatherbacks; Bycatch rates 10x higher than tuna fisheries Pelagic Longline Swordfish Fishers deploy hook sets at night with chemical lightsticks to attract or illuminate baits to hooks Sea Turtle rescue in the ETP …and closer to home • Every fall and winter, the local sea turtles off Long Island need to return south to the warmer waters of the Caribbean and the Gulf of Mexico • Sea turtles that remain can become “cold stunned” – <50°F – Call the Riverhead Foundation: 369-9840 Marine Reptiles: Sea Snakes • Approximately 55 species of sea snakes are found in the tropical Indian and Pacific oceans • The tail end of sea snakes is flattened into a paddle-shape for swimming • A few species return to land to lay eggs, but most give birth to live young underwater – ovovivipous Marine Reptiles: Sea Snakes • Sea snakes are closely related to cobras; the most venomous of all snakes • Sea snake bites can be fatal to humans; extremely venomous – Why? Marine Reptiles: the Marine Iguana • The marine iguana is found on the Galapagos Islands, off the coast of South America • Marine iguanas survive in the cold, upwelled waters off the Galapagos by frequently basking on the rocks to raise their body temperature • Feed on algae • Efficient swimmers Marine Reptiles: Saltwater Crocodile • The saltwater crocodile inhabits mangrove swamps and estuaries in the eastern Indian Ocean, Australia, and some of the western Pacific islands • Very aggressive; fatal attacks on humans • Commonly 20ft long • Inhabits coast, rivers and open sea © Susan Flashman/ShutterStock, Inc.