Watching a sea otter eat can look surprisingly deliberate. Floating on its back, the animal may balance a clam, crab or snail on its chest, pick up a stone and repeatedly strike the prey until the shell gives way. Sometimes the strategy is reversed: instead of wielding the rock like a hammer, the otter uses a hard object as an anvil and smashes its meal against it. This isn't simply an entertaining feeding trick. Research suggests that tool use can change which foods sea otters are capable of eating, protect their teeth from damage and help explain why individual otters develop remarkably different diets. In some environments, the difference between biting and using a rock could even have consequences for survival.
