The leatherback has a smooth leathery skin with prominent longitudinal ridges on its shell. It is dark gray, brown, or black with whitish spots on neck and limbs. A single female may deposit several clutches of eggs each year. The eggs are round, covered with a parchment-like skin, and about as big as golf balls. The number of eggs laid ranges from 85 to 500.
Green turtles are primarily vegetarian as adults.
Leatherbacks feed almost exclusively on jellyfish. This may account for its relatively common occurrence in cold northern waters where jellyfish are seasonally abundant. Marine turtles migrate considerable distances between their nesting and feeding grounds. Leatherbacks have been recorded 3,000 miles from their nesting grounds. The mechanisms of sea turtle navigation have been intensely investigated, but the cues or sensory systems involved are still unknown.