Turtles are among the oldest living reptiles and have not evolved greatly from their prehistoric ancestors. However all marine turtles are endangered for a number of reasons. Their eggs are poached , their flesh and oil are eaten , their shells are used for jewellery, they are caught in fishing nets and drown, and plastic rubbish chokes them. The biggest threat is rising sea levels which are flooding their nesting grounds. Increased sea levels are caused by global warming.