Movement

Amoebas move by changing their shape. First, an amoeba extends a part of its jellylike body outward, like a stubby finger projecting out of a closed fist. This projection is called a pseudopod, or false foot.

The amoeba then slowly pours the main part of its body into the pseudopod, which makes the pseudopod grow bigger and bigger. Eventually the pseudopod gets so big that it becomes the whole body. New pseudopods form as old ones disappear. Most exist for only a short time, then flow back into the main body. Pseudopods can be long and thin or short and stubby in shape. Often many pseudopods form at the same time. This makes it seem as if the amoeba were starting off in several different directions at once. But most pseudopods exist only for a short time, then flow back into the main body.

Eating

For food, amoebas depend mainly on plants and other one-celled animals. These include algae, bacteria, and the tiny protozoa that live in water, usually in streams and ponds. Since amoebas do not have mouths, they have to find some other way to take in food. Once again their pseudopods come into action, this time by reaching out to surround their food and flowing over it.

Water is also taken in by a primitive method, which is called osmosis. By this process, an outer membrane, or lining, on the amoeba allows water to pass into the amoeba's cell where it can be used.

Breathing and waste disposal

The amoeba is also able to breathe and take in oxygen through its membrane. Carbon dioxide, the waste product of breathing, leaves the cell through its membrane. The waste products of food are disposed of in the same way.