고등학교 공통영어2 (NE능률 민병천) 연계 글

Picture a calm morning off the coast of central California, where long ribbons of kelp rise from the rocky sea floor. A small animal covered in thick fur floats on its back among the kelp, with its front paws resting on its chest. It is a sea otter, one of the smallest marine mammals. An adult female here weighs only about 20 kilograms.

When the otter gets hungry, it dives to the sea floor in search of sea urchins, crabs, and clams. It stores its prey in a loose pocket of skin under its arm, so its paws stay free to seize more. Back at the surface, the otter rolls over on its back and uses its chest as a table. To open hard-shelled clams, it may use a rock as a tool. It places the rock on its chest and strikes each one against the stone until the shell cracks. Then it eats the soft meat and dives again.

Unlike whales and seals, a sea otter has no thick layer of blubber. First, its body turns food into heat so quickly that the otter must eat about a quarter of its weight every day. Second, it has the densest fur of any mammal, with up to about a million hairs in each square inch. The otter spends a large part of each day taking care of this coat. Rubbing and cleaning its fur, it pushes tiny bubbles of air close to its skin. This trapped air helps the otter retain its body heat and stay afloat.

The otter's appetite has a strong impact on the whole kelp forest. Sea urchins feed on kelp, and when nothing keeps their numbers down, they can strip a forest bare. By eating urchins day after day, the otter allows the kelp to flourish. The healthy kelp, in turn, provides food and shelter for numerous fish and other sea creatures. For this reason, scientists call this small predator a keystone species; its presence shapes the community around it.

When it is time to rest, the otter wraps itself in kelp so that it will not float away in its sleep. Held in place by the kelp, the small guardian of the forest floats quietly until hunger sends it diving again.