The largest living species of sea turtle is the leatherback sea turtle (Dermochelys coriacea). Unlike other sea turtles, leatherbacks have a unique, leather-like shell instead of a hard, bony carapace. Adult leatherbacks can reach lengths of up to 2.9 meters (9.5 feet) and weigh over 600 kilograms (1,300 pounds), making them the largest marine reptiles in existence today. These turtles are known for their deep-diving capabilities, often diving to depths of 1,200 meters (3,900 feet) in search of jellyfish, their primary food source. Due to various threats, including habitat loss and climate change, leatherbacks are classified as vulnerable.