Sea Otters: Keepers of the Kelp Forest

Sea Otters: Keepers of the Kelp Forest

1Along the rocky coast of the northern Pacific Ocean, a tall seaweed called kelp grows from the sea floor up toward the sunlight. These underwater forests are home to fish, crabs, snails, and one furry animal that spends most of its life in the water: the sea otter.

2Whales and most seals have a thick layer of fat, called blubber, that keeps them warm in cold water. Sea otters do not. Instead, they have the thickest fur of any animal. Their fur traps tiny bubbles of air next to the skin, and the air keeps the cold water away from their bodies. A sea otter spends a large part of each day grooming, rubbing and fluffing its fur to keep it clean. Dirty or tangled fur cannot hold air, so an otter with dirty fur can quickly become dangerously cold.

3Staying warm takes a lot of energy, so sea otters must eat often. They dive to the sea floor to find crabs, clams, and sea urchins. Sea otters are also one of the few mammals that use tools. An otter floats on its back, sets a flat rock on its chest, and bangs a hard shell against the rock until the shell cracks open. Some otters keep a favorite rock in a loose pocket of skin under one arm.

4Sea otters even sleep in the water. Before a nap, an otter may wrap itself in long strands of kelp. The kelp holds the otter in place like an anchor, so it does not drift away while it rests. Mother otters carry their babies, called pups, on their bellies. A young pup's fur is so fluffy and full of air that the pup bobs on the water like a cork and cannot dive yet.

5Sea otters also help keep kelp forests healthy. Sea urchins are spiny animals that eat kelp. When there are too many urchins, they can eat through a kelp forest until little is left. Long ago, people hunted sea otters for their fur, and in many places the otters disappeared. Without otters to eat them, urchins spread, and many kelp forests shrank. Later, laws protected sea otters. When otters returned to some coasts, the kelp began to grow back.

6Scientists call the sea otter a keystone species. A keystone is the stone at the top of an arch. It holds the other stones in place, and if it is removed, the arch can fall apart.