Kate Salsky Pre-Ap Biology March 12th, 2014 - VU
The earthworm, Lumbricus terrestris, is a member of the phylum Annelida. An earthworm is well adapted to a life of burrowing through the soil, its streamlined shape making this tunneling easier. Its mucus coating also helps oxygen pass through the earthworm's skin while it's in the air or underwater. The earthworm moves through the soil by sucking the soil in its path into its mouth with the aid of its muscular pharynx. As material passes through its tube-like digestive system, sand grains in the gizzard help grind the food obtained from the soil, which is digested and absorbed in the intestine.
- predators: snakes, bird, rodents
- prey: dead/decaying matter
- habitat: at/under the surface of soil
Digestive System: At A Glance
The digestive system of an earthworm is one of its most important systems. The parts of an earthworm's digestive system include: mouth, pharynx, crop, gizzard, esophagus, intestine, and anus. As the earthworm burrows its way through soil, they eat the soil in order to 'carve' their way around. From the mouth, food is pushed into the pharynx, where it is moistened by mucus, allowing for an easier transition into the esophagus. The absorbed nutrients then move down the esophagus into the crop, where it is then transferred to the gizzard, where muscles grind nutrients out of the absorbed food. Enzymes released by the wall of the gizzard also help break down food. The food later moves to the intestine, where it's actually digested, and wastes are expelled through the anus.
Earthworms have many adaptations that benefit the way they live. For example, a main adaptation that they have is setae. Each segment on an earthworm's body is covered in setae, which provide grip to the worm when it is maneuvering through the soil. Another adaptation that earthworms have is its narrow body. This streamlined body shape makes the worm able to live in underground, as well as making it easier for the worm to get through the soil.