Leatherback sea turtles are voracious creatures and they tend to eat twice as much as their own weight. They have scissor-like jaws but feed mainly on soft-bodied animals like tunicates, siphonophores, cephalopods and salps. However, they usually feed almost exclusively on jellyfish which is strange because the jellyfish are made up of water and therefore, do not form part of a healthy source of nutrients for the turtles. In search of California jellyfish, the leatherbacks of the Pacific Ocean tend to migrate 6,000 miles from Indonesia. Apart from jellyfish, they also feed on mollusks, sea urchins, fish and squid.
It appears as if leatherbacks do not seem to recognize the difference between plastic sandwich bags and jellyfish. Recently, the stomachs of these turtles are found to contain cellophane or plastic. About one-third to one-half of all leatherbacks is found to ingest plastic bags perhaps by mistake.
Sources:
“The Leatherback Sea Turtle”. Michigan State University
“Endangered: Leatherback Sea Turtle”. American Museum of Natural History
“Information About Sea Turtles: Leatherback Sea Turtle”. Sea Turtle Conservancy