The neck and limbs are thick and feebly retractable. Average carapace length is 61 inches and adults generally weigh from 640 to 1,300 pounds. The triangular-shaped carapace is covered with a layer of rubbery skin rather than horny shields, and it has seven longitudinal ridges. The head and neck are black or dark brown with a few white or yellow blotches. The paddle-like clawless limbs are black with white margins and may have white spots.
Hatchlings are dark brown or black with white or yellow carapacial keels and flipper margins.
The principle food is jellyfish, but the diet is also known to include sea urchins, squid, crustaceans, tunicates, fish, blue-green algae, and floating seaweed. The eggs are laid at night in clutches of 80 to 85. As many as 11 clutches may be laid in a season with an average internesting period of 10 days. The white spherical eggs are approximately 2 inches in diameter. Incubation takes from 55 to 74 days and emergence of the hatchlings occurs at night.