What Are the Structural Characteristics of an Earthworm?
Earthworm is an animal with a long, rounded body divided into compartments known as segments. As earthworms burrow through the soil, they swallow mouthfuls, digesting tiny food particles and passing the waste out behind them, leaving the familiar worm casts. The worms help to mix soil and leaf litter as they burrow through it.
An earthworm’s body is streamlined and every segment contains a number of bristles called setae. The streamlined shape helps the earthworm travel through soil, and the bristles improve grip if the soil is wet. Circular muscles surround every segment of an earthworm’s body.
Earthworms are also called night crawlers because they burrow down in the ground during the day and come above ground at night to feed. An earthworm has a small brain, a digestive system, a reproductive system and a circulatory system with five pairs of hearts. Earthworms breathe through their skin instead of with lungs. In Australia there are giant earthworms which can reach a length of 3m (10 ft).
Earthworm Fact: If you cut an earthworm in two, the rear half will always die, and the front half may live to become another whole worm. This is called regeneration. The front part must be long enough to contain the clitellum and at least 10 segments behind the clitellum. This makes up about half the length of the worm. The new posterior segments grown will be slightly smaller in diameter than the original segments and sometimes a bit lighter in color.