They eat sponges, tunicates, shrimps, and squids. Leatherbacks have delicate scissorlike jaws that would be damaged by anything other than their normal diet of jellyfish, tunicates, and other soft-bodied animals. Researchers continue to study the feeding habits of flatbacks. There is evidence that they are opportunistic feeders that eat seaweeds, cuttlefish, and sea cucumbers. B. Eating habits.
Some species change eating habits as they age.
For instance, green sea turtles are mainly carnivorous from hatchling until juvenile size they then progressively shift to an herbivorous diet.