Otters have skin pockets, located under their forearms near the armpit area, which are used as storage for rocks or for prey that they have already caught. These pockets allow the otters to keep their hands free. These sea mammals are one of the few animals to use tools. The rocks stored in otters' skin pockets are used to crack open the hard shells of prey such as mollusks or clams. An otter will float on its back with the rock on its belly, and then crack the shellfish against the rock to get to the shellfish's insides.
More about sea otters:
- Sea otters spend about eight hours each day hunting for food or eating, because they must consume roughly one-fourth of their body weight per day in order to survive.
- Milk from sea otters has an extremely high fat content, at about 25%. By comparison, whole cow’s milk has a fat content of 4%.
- The sea otter is the only marine animal without blubber to keep warm, but it does have the thickest fur of any animal.