Taxonomy

Dermochelys coriacea is the only living member of the Dermochelyidae family, sister taxon to the family Cheloniidae, which contains all other extant sea turtles (6 species in 5 genera).

Dermochelyidae is distinguished by the lack of a hard, rigid carapace (shell) comprised of keratinous scutes - a feature that all other sea turtles share. Instead it has a carapace formed of flexible tissue, overlain by a matrix of small (1–2cm) bones called osteoderms and covered in a layer of skin.

It possesses 7 lateral ridges running the length of the carapace, although other extinct Dermochelyidae species have been characterised by the possession of different numbers of such ridges.

Its skeleton has a high cartilage ratio making it highly flexible and it has particularly long front flippers.

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Glossary
Keratinous

Made out of keratin, the protein which is the main component of our hair and nails.

Pelagic

Any water in the sea that is not close to the bottom or near to the shore.

Salps

Free-floating tunicates - a group of sac-like filter feeders.

Scutes

Hard, external, plate-like structures similar to scales, formed from lower layers of skin.