National Geographic : 2019 Oct
Shell length: about 7 ft Weight: up to 2 tons Stomach Ribs Fat Esophagus CONSERVATION STATUS Critically endangered Endangered Vulnerable Insufficient data Shell length 3.5 ft (maximum) Scute 3.1 ft 200 ft Female Claw 1in Scute Rib Stomach Liver 4ft Brain 300 ft 500 ft PRIMARY ADULT DIET Invertebrate Marine plant Horseshoe crab Sponge Crustacean Mollusk Fish 3ft 2.3 ft 835 ft 2.1 ft Diet Maximum diving depth 585 ft 160 ft Brain Salt glands Skin Bone Lungs Liver 6ft 4,000 ft 3in Fat Esophagus Lungs Ribs Scute Vein cool blood Artery warm blood INDIAN OCEAN PAC. OC. ATL. OC. SOUTH AMER. NORTH AMERICA EUROPE ANTARCTICA AUS. ASIA AFRICA OREGON, U.S. NEW GUINEA 12,77 4mi Longest documented sea turtle migration INDIAN OCEAN PACIFIC OCEAN PACIFIC OCEAN ATLANTIC OCEAN SOUTH AMER. NORTH AMERICA EUROPE ANTARCTICA AUS. ASIA AFRICA EQUATOR Population at highest risk Range Nesting area FERNANDO G. BAPTISTA, JOHN KAPPLER, DIANA MARQUES, AND EVE CONANT, NGM STAFF; MESA SCHUMACHER SOURCES: JEANETTE WYNEKEN, FLORIDA ATLANTIC UNIVERSITY; BRIAN HUTCHINSON, RODERIC MAST, OCEANIC SOCIETY MAP SOURCES: SCOTT BENSON, SOUTHWEST FISHERIES SCIENCE CENTER, NOAA; STATE OF THE WORLD’S SEA TURTLES (SWOT), OBIS-SEAMAP SEA SURVIVORS HARD SHELL FLEXIBLE SHELL Sea turtles have navigated the oceans since the time of the dinosaurs more than 100 million years ago. Today all seven species are under threat at every life stage because of human activities, from accidental capture in fishing nets to overharvesting of eggs and widespread plastic pollution. Six of the seven species have hard shells fused to their ribs and over- laid with keratin scutes. They also have claws on their flippers. Illustrations in approximate, relative scale Leatherbacks are the only living species with unfused ribs, rubbery skin over layers of connective tissue, and a flexible shell of bony plates. All sea turtles have glands around the eyes to remove excess salt from their bodies. Interlocking scutes pre vent water loss and cover flattened, fused ribs that separate at the tips. The hawksbill is the only turtle with overlapping scutes and serrated edges on its shell. Adult males can be identified by their long tails, which hold sex organs. Front flippers act as wings for propulsion. Rudderlike hind feet stabilize and steer. The green turtle’s serrated beak helps tear marine plants. KEMP’S RIDLEY Lepidochelys kempii Accidental capture and egg overhar vesting have made the smallest sea turtle the world’s most threatened. LOGGERHEAD Caretta caretta The most abundant sea turtle in the U.S . is named for its giant head. Its strong jaws can crack conch shells. FLATBACK Natator depressus The flatback makes the shortest migra tion: around Australian waters. It has a nearly flat body with flared edges. GREEN Chelonia mydas Named for a layer of green fat under their shell, green turtles start as omni vores before turning into herbivores. HAWKSBILL Eretmochelys imbricata Hawksbills’ intricately patterned, trans lucent scutes have long been used to decorate jewelry and luxury items. OLIVE RIDLEY Lepidochelys olivacea The most abundant species exits the sea en masse to nest, a safetyin numbers strategy against predators. LEATHERBACK Dermochelys coriacea The largest and deepest diving turtle makes the longest migrations and can weigh up to 2,000 pounds. Slippery diet A long, barbed esoph agus traps jellyfish and keeps them moving into the stomach. Migration cue Pale skin lets light into the pineal gland, which can track day length and spur migration. Archelon (extinct) This giant that roamed the seas 75 million years ago had unfused ribs, like its close rela tive, the modern leatherback. Waxy skin covers a shell of coinsize bony plates that can withstand the pressure of deep dives. Transferring heat Blood flowing to flippers warms returning cold blood, maintaining a warmer core than hardshell turtles have.