The Two Turtles, Side by Side
An adult Olive Ridley weighs around 45 kilograms. An adult Leatherback can weigh over 900 kilograms, roughly the mass of a small car. These are not variations on the same animal. They are, in almost every measurable way, opposites that happen to share an order.The Olive Ridley (Lepidochelys olivacea) has a hard, bony carapace with distinct scutes, a diet built around crustaceans, fish eggs, and jellyfish, and a body plan that has remained largely unchanged for millions of years. The Leatherback (Dermochelys coriacea) has no bony shell at all, its back is covered in a leathery, oil-saturated skin reinforced by thousands of tiny bone fragments called osteoderms. It is the only living member of its family, Dermochelyidae, a lineage that diverged from other sea turtles roughly 100 million years ago. Its diet is almost exclusively jellyfish, which means it can thrive in waters cold enough to kill most reptiles. Leatherbacks have been recorded diving to over 1,000 metres.One is a gregarious, warm-water nester that travels in enormous aggregations. The other is a solitary, wide-ranging deep-diver that tolerates near-polar temperatures. Both nest on Indian shores.
