What's Inside?Earthworm Dissection!

By Ching-Hung Chang (Clement) Vu-PAP Bio-1

Objective

Students will learn about the anatomy and physiology of earthworms by dissecting and research Earthworms.

What are Earthworms?

Earthworm, Lumbricus Terrestris, are member of phylum Annelida. Having a brain and simple nervous system, Earthworms are considered the most developed worm. They are segmented and symmetric bilaterally. Earthworms have no respiratiory system; They intake oxygen directly through the skin. A simple circulatory system brings oxygen around the body.


Earthworms can be benificial to agriculture. Tunneling improves soil permeability. They bring up minerals underground to surface where plants can absorb. Earthworms can also help get rid of harmful chemicals.

Dissection

Earthworm Digestive System

Earthworm's digestive system compose of mouth, pharynx, esophagus, crop, gizzard, intestine, and anus. Soil first enter from mouth to pharynx where mucus is produce to help the food slide. Esophagus is where calcium carbonate is added. It is used to neutralize the acid that are formed when food decay. Food is then stored in crop where it is mixed with other food. After mixture, glands will secrete enzymes that help break down organic molecule. Next, mixture is sent to intestine where friendly bacteria eats the matter. The waste of the bacteria are vitamins, minerals, carbohydrates, where Earthworm will take in. At last, undigested materials are send out through anus.

How Much Do You Know About Earthworms?