The Most Earthwormy of Them All

Earthworm dissection lab March 13, 2014 Zhengde Du

Objective

Today, students will observe the internal and external structure of the earthworm and label the different segments.

Lumbricus terrestris

Earthworms are in an order of Haplotaxida. They belong in the kingdom Animalia under the phylum Annelida. The earthworm's body is segmented and may look like many little rings fused together. The earthworm may have up to 100-150 segments and each segment includes muscles and bristles known as the setae. Segmentation of the earthworm's body provides movement and allows the earthworm to become flexible and strong. They are well adapted to living in soil and the mucus coating helps oxygen pass through the earthworm when it is out of the soil, or underwater.

Background information

Earthworms are mostly in soil but there may be times when earthworms are in a different habitat such as an underwater location. Earthworms decompose dead organisms in the soil and keep it healthy. They are the main contributors to nourishment and enrichment in soil. When earthworms move through the soil, they make tiny tunnels that allows water to properly enter the ground and into the roots of plants. They also eat organic matter such as decaying leaves ( which is pretty useless to the plants) and they release their wastes known as castings which provide nutrients in the soil.

Earthworms do not prey on anything since they eat decaying leaves but they do have predators such as moles, birds, and raccoon. There are many other predators since Earthworms contain a lot of nutrients but those are just a few examples. However, earthworms have ways to hide from their predators. They adapted to have brown skin to camouflage with the soil and they also have segmented bodies to become flexible.

The Digestive System

The digestive system starts with the mouth. The worm will eat soil, decaying plant and animal materials. Then, the gizzard crushes the food, and it is sent to the intestines. The intestines absorb all the nutrients and the remaining material is sent to the excretory system to be excreted.

Want to test your knowledge of an Earthworm? Check this quiz out!