This is the largest marine turtle. The carapace length is as great as 244 cm (96 in.), with an average of 155 cm. It has a weight of 290-590 kg. The carapace is teardrop-shaped and covered with leathery skin, as opposed to horny plates. Hatchlings are black to dark brown, and the keels on the carapace and the margins of the flippers are white to yellow. Leatherbacks can probably exchange gases through their skin as indicated by sphincter muscles in the pulmonary arteries that can divert blood from the lungs to the skin. The oil found within both the skeleton and flesh of this species may lessen decompression problems during rapid diving and resurfacing. Leatherbacks can dive to a depth of 475 meters, nearly the depth attained by the bottle-nosed dolphin. The leatherback is able to maintain its body temperature several degrees higher than in surrounding waters. This explains its ability to migrate into cold waters in upper latitudes where it feeds on the abundant coldwater jellyfish. The preponderance of clear plastic debris in the oceans has had a negative impact on the survival of leatherbacks. These turtles consume plastic bags, jugs, and sheets because they look like jellyfish. This leads to intestinal blockage and starvation.
Only subadults and adults are seen in coastal waters; juveniles are seldom seen anywhere. Leatherbacks are the most pelagic of sea turtles. They forage in coastal and offshore waters but occasionally wander close to shore and into estuaries. They occur in Virginia’s coastal waters during the warmer months and stay longer than other species. Breeding is not likely to occur in Virginia. This species prefers water deeper than 15 feet.
The diet of this species consists of soft-bodied animals such as jellyfish and tunicates, together with associated juvenile fishes, amphipods and other organisms. Although they are not agile enough to catch fish on their own, they will forage from gill and pound nets. In Virginia, leatherbacks feed primarily on the moon jellyfish and sea nettle.