Leatherback turtles are endothermic. This means this they can maintain a fairly consistent body temperature despite environmental changes. This is different than any other sea turtle. They are able to keep their body temperature around 79 degrees Fahrenheit (26 degrees Celsius) without sun bathing due to counter-current heat exchangers in their limbs and then transferred via veins and arteries. Not only does this help to keep them warm in freezing waters, but also prevents them from over-heating. 

Leatherback sea turtles are subjected to high amounts of salt water throughout their lives. They are able to prevent toxicity and maintain osmotic balance by filtering salt out through an exocrine gland called salt glands behind their eyes and retaining the needed water. 

Leatherback sea turtles have pointed cusps on the front of their jaws. This helps them hold on to jellyfish, their main diet.  Once in their mouth, they have sharp papillae that help to move the food to the back of their throat. The papillae help the leatherback to hold the jellyfish in the throat while expelling excess water. Turtles do not have mucus glands. Instead, they have salivary glands.  The leatherback has a long esophagus that allows them to store and process foods all the time. Processed foods are pushed down the digestive tract into the large and small intestines and expelled through the rectum.

Leatherback sea turtles have lungs just as any other reptile. The lungs run along the upper part of the carapace, or top shell. They will come to the surface of the water to take a breath and dive back under again. Leatherbacks are able to build up a storage up oxygen in their blood supply and slow their heart rate and respirations to conserve oxygen and energy.

The mouth of the leatherback sea turtle does not contain any teeth. Instead has large cusps on the front to grasp prey.  The leatherback sea turtle is the only sea turtle thats spine is not fused to the upper carapace or shell. They have 7 scutes, which are the ridges on its back, from the front of the  carapace to the back near its tail. The belly, or bottom side of the turtle, is called the plastron. Although the front flipper appear like human fingers, the joints are all fused together so the flipper is solid.