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| The family Dermochelyidae contains a single living species which is the world's largest living turtle, Dermochelys coriacea. It exceeds 2 m in shell length and attains weights that exceed 900 kg. While they occur in tropical waters around the world, they will enter cold temperate waters. Leatherbacks get their name from the oil soaked connective tissue that makes up its carapace, giving it a leather-like texture. Under this tissue is a layer of small dermal bones. The cartilage in this turtle is unusual in that it is vascularized, other vertebrates lack blood vessels in cartilage. It can dive to at least 1200 m, and stay submerged for up to three hours. Leatherbacks also have the ability to maintain a body temperature 3-18 degrees Celsius above the ambient water temperature. The leatherback is unique in its ability to make long, deep water crossings and in its specializations for feeding on jellyfish. The other sea turtles tend to stay in shallow coastal waters. Fossil dermochelids in several genera are know from the Eocene of North America, Europe, and North Africa. |