Marine sea turtles are a fundamental link in marine ecosystems as they help maintain the health and vitality of sea grass beds and coral reefs.  Sea turtles are specially adapted for lfe in a marine environment and they possess flippers and a streamlined body to enhance their mobility in an aquatic domain  Usually female sea turtles come ashore onto sandy beaches in large groups called arribadas and then engage in mass nesting.  Female sea turtles can lay up to 100 eggs in each nest.  Female sea turtles crawl onto the beach and dig U- shaped holes into the sand above the high tide line.  There is usually an interval of ten to fifteen days betweeen the laying of each batch, called a clutch of eggs.  From hatchling to adult, Loggerhead sea turtles increase their weight more than six thousand times.  Hatchling Loggerhead sea turtles weigh onlhy 0.05 pounds or 20 grams. In one nesting season female Leatherback sea turtles can lay 12 clutches of eggs with 65 to 85 eggs in one clutch.  Leatherback sea turtles lay eggs of various sizes in a single clutch.  Small, yolkless eggs are laid alongside viable eggs. Pacific Loggerhead sea turtles migrate over 7,500 miles ( 12,000 kilometers ) between nesting beaches in Japan and feeding grounds off the coast of Mexico.During the three months that she breeds, a female Loggerhead sea turtle will travel hundreds of miles to nest and will lay over 35 pounds of eggs. Loggerhead sea turtles are named for their large, powerful jaws which enables them to feed primarily upon whelks and conch.  On average a Loggerhead sea turtle weighs 250 pounds although some specimens weighing over a thousand pounds or 455 kilograms have been recorded. Some specimens of Leatherback sea turtle are nine feet in length and weigh 2015 pounds or 916 kilograms.  On average the Leatherback sea turtle measures six feet in length, four feet in width and weighs 880 pounds or 400 kilograms. Leatherback sea turtles travel up to 12,000 kilometers and dive as deep as 1200 meters.  For the Leatherback sea turtle it's main source of food is jellyfish such as the cannonball jellyfish, the lion's mane jellyfish and the Portuguese-Man-of-War jellyfish. Leatherback sea turtles have many rows of spikes in their throats to help hold down their slippery food.  Loggerhead sea turtles have callus-like traction scales beneath their flippers that allow them to walk along the ocean floor hunting whelks and conch.  Leatherback sea turtles are unique in that their carapace and plastron consists of a thick layer of cartilage strengthened by thousands of imbedded tiny bones.  Thus the Leatherback sea turtles possess a rubbery shell unlike the hard shell of other sea turtles. Leatherback sea turtles can change their body temperature and they possess a specialized circulatory system that minimizes heat loss plus layers of subcutaneous fat to insulate them from the cold. Kemps Ridley sea turtles are the most endangered sea turtles in the world with just a thousand breeding female turtles left to propogate the species and prevent extinction.  Leatherback sea turtles have high red blood cell concentrations and can therefore bind oxygen with a superior ability.  The muscle of Leatherback sea turtles has a high content of oxygen-binding protein myoglobin.  During long dives the Leatherback sea turtle shunts blood away from tissues tolerant of low oxygen levels and moves it toward the heart and brain.  Leatherback sea turtles dive in a cycle that mirrors the daily rising and sinking of the dense layer of tunicates. jellyfish and plankton upon which they feed.  Leatherback sea turtles swim at speeds of 5.8 miles per hour or 9.3 kilometers per hour.  Green sea turtles can stay underwater for as long as five hours.  Their heart rate slows to conserve oxygen - nine minutes may elapse between heartbeats.

The Leatherback sea turtles and the Loggerhead sea turtles are threatened directly by commecial fishing, particularly by-catch in the pelagic longline fleet and by the loss and degradation of nesting beaches.  Pelagic longline operations are wasteful with a typical by-catch of 50 percent or more of non-target species.  About 120 fishing vessels operated in the pelagic longline fishery in 2008.  Between 2001 and 2008 the pelagic longline fleet snared 4,839 Loggerhead sea turtles and 6,626 Leatherback sea turtles.  Thus a total of 11,465 sea turtles were slaughtered by the pelagic longline fishery between 2001 and 2008.  About seven million deadly hooks are set each year by the pelagic longline fishery.  The National Marine Fisheries Service estimates that 635 Loggerhead sea turtles will still be killed by the Atlantic pelagic longline fishery each year even with the introduction of circle hooks and other by-catch reduction measures.  At a cost of tens of millions of dollars the National Marine Fisheries Service developed the turtle extruder device.  The turtle extruder device is a small, metal grid trapdooor inside a trawling net that allows shrimp to pass to the back of the net while the turtles escape to safety before becoming entrapped or entangled.  Since 1989 federal law requires that the turtle extruder device be installed on the nets of all United States fishing trawlers working in areas populated by sea turtles.