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. The turtles are believed to reach maturity in 6 to 10 years. Although they are air-breathing animals born on land, leatherbacks, like all sea turtles, spend their lives in the ocean. Females return to land only to lay their eggs.
Leatherbacks are unique among sea turtles in that their primary food is jellyfish.
They also will eat fish, mollusks, squid, sea urchins, and other marine creatures. Adult leatherbacks ply the seas alone, except on occasion gathering to feed in areas with large numbers of jellyfish. Sea turtles swim with grace and speed and have been clocked at an amazing 22 miles per hour. All other sea turtles are confined to the warmer regions of the world's oceans. In northern waters they are reported to sometimes enter shallow estuarine bays.