Loggerhead and hawksbill turtles are particularly vulnerable. Leatherback, green sea and hawksbill sea turtles use the beaches for nesting. The loggerhead, Kemp's ridley, olive ridley, and hawksbill sea turtles are omnivorous their entire life. Four species of sea turtle (green, Pacific ridley, hawksbill, and leatherback) nest on the beaches. Turtles include the threatened Green sea turtle and the endangered Hawksbill sea turtle. Sea turtles, particularly hawksbill sea turtles, feed on sponges. Adult hawksbill sea turtles are primarily found in tropical coral reefs. Green turtles and hawksbill turtles are in the coastal waters where nestling also takes place. The reefs also serve as a nesting ground for Hawksbill and Green sea turtles. Several characteristics of the hawksbill sea turtle distinguish it from other sea turtle species. The surrounding waters are feeding areas for hawksbill turtles. The island is an important breeding ground for hawksbill and green turtles. This is because the green and hawksbill sea turtles have higher P450 2-like protein expression. Likewise, other marine creatures such as seaturtles and hawksbill turtles can be encountered. Known as bycatch, this is a serious threat to hawksbill turtles.