Eight Arms

A True Book

An octopus is a soft animal that lives in the sea. It has no bones at all. It has a round body, a big head, and eight long arms. Octopuses live in oceans all over the world, from warm shallow water to the cold, dark deep. Some octopuses are smaller than your thumb. Others are bigger than a grown-up.

Here is a fact that surprises most people. An octopus has three hearts. Two of the hearts pump blood past the gills, where the animal takes in air from the water. The third heart pumps blood to the rest of the body. And the blood is not red like yours. It is blue, because it carries a metal called copper.

An octopus has a very big brain for an animal with no bones. It also has a lot of brain cells in its arms. About two thirds of all its brain cells are out in the arms, not in the head. Each arm can do some of its own thinking. People sometimes say an octopus has nine brains, one in the head and one for each arm.

Each arm is covered with round, sticky cups called suckers. A big octopus can have about two thousand of them. The suckers can hold on to things very tightly. They can also taste. An octopus does not have to put food in its mouth to learn what it is. It can taste things just by touching them with its arms.

Because an octopus has no bones, it can squeeze into places that look far too small. The only hard part of its body is its beak, which is shaped like a parrot's beak. If the beak can fit through a gap, the rest of the octopus can follow. A big octopus can slip through a gap not much wider than its beak.

Octopuses are the masters of hiding. The skin has thousands of tiny spots called chromatophores that open and close to change its color in less than a second. An octopus can turn red, brown, white, or speckled. It can also change the bumps on its skin, so it can look just like a rock or a clump of seaweed.

Here is a strange part. Scientists think most octopuses cannot see color the way you do, yet they match the colors around them very well. Nobody is completely sure how they do it. Some scientists think the skin itself can sense light. Others think the octopus uses its odd-shaped eyes in a clever way. It is still a mystery.

When an octopus needs to get away, it has a few tricks. It can shoot out a cloud of dark ink, which makes a smoky blur in the water. Then it zooms off by squirting water out of a tube on its body. This is called jet power. It works a little like a balloon zipping around the room when you let the air out.

Octopuses are good at solving puzzles. In labs, they have learned to open jars by twisting off the lids from the inside. They can find their way through mazes. One kind, called the veined octopus, has been seen carrying two halves of a coconut shell across the sand. Later it hides inside, using the shell as a portable home.

Most octopuses live alone and do not live very long. Many live only one to five years. A mother octopus lays her eggs, sometimes thousands of them, and takes care of them. She keeps them clean and protects them. She hardly eats while she waits. A deep-sea octopus was once watched guarding her eggs for more than four years.

The giant Pacific octopus is the biggest kind. With its arms stretched out, it can be about sixteen feet across, as long as a small car. It can weigh more than a big dog. The smallest kind is only about an inch long. It would fit on the top of your finger, and it is still a true octopus.

If an octopus loses part of an arm, it can grow a new one. Some octopuses stack shells and stones to build a little wall around their den. Octopuses have been living in the sea for a very long time. Next time you see a picture of an octopus, remember: it has three hearts, blue blood, and arms that can taste.