Earthworms Life Cycle

Earthworm Dissection Pre-AP Biology April 7, 2014 - Ms. Vu

Lumbricus terrestris

The earthworm is a tube shaped, and segmented animal which is commonly found living in soil and they feed on live and dead organic matter. Its digestive system runs the entire length of the body. The earthworm falls under the kingdom: Animalia, the phylum: Annelida, the class: Oligochaeta, and subclass: Haplotaxida. An earthworm has a double transport system consisting of coelomic fluid that moves within the fluid filled coelom along with a simple and closed circulatory system. The earthworms central nervous system consists of two ganglia which are above the mouth and on either side, it is connected to a nerve and cord running back along its length which are connected to the sensory cells and the motor neurons in each segment.

Fun Fact

In one acre of land, there can be approximately one million earthworms.

Today's Objectives

The students, through the dissection, will learn about the internal and external anatomy of a Earthworm. We will focus on the structures, organs, and functions on the digestive system. We will understand their niche, the ecological role that Earthworms play.

Evolutionary relationships of the Earthworm.

The Digestive System of the Earthworm.

The digestive earthworm of the worm is split up into many regions, each of which serves a certain function. This system consists of the esophagus, the pharynx, the crop, the gizzard, and the intestine. Food, for example soil, enters the earthworms where it is swallowed by the pharynx . Then the soil passes through the esophagus. After this food passes through the crop, it is stored and then eventually moves into the gizzard. The gizzard uses stones that the earthworm eats which basically grinds the food down completely making it easier to process. The food then moves into the intestines as gland cells which are in the intestine and the fluids released help to digest food. The wall of the intestine contain blood vessels in which the digested food is absorbed and is then transported to the rest of the body.