Earthworm Dissection Lab Pre-Ap Biology



Earthworms are a species that are called terrestris. They belong to the kingdom of Animalia under phylum Annelida. Their bodies are divided into segments and the furrows would mark the division between each segment of the body.


We will be observing the external and internal structure of the earthworm. We will also be learning the functions of the circulatory and digestive system of the earthworm.

Earthworm Dissection Tutorial

Dissection Tools & Materials

Digestive System:

The digestive system is one of the most important systems in the worm. The digestive system consists of the mouth (segment 1) , pharynx (segment 2-6), esophagus (segment 7-14), crop (segment 15-17), gizzard (segment 18-20), intestines (segment 21-111) , and the anus (last segment). The food particles pass from the mouth to the pharynx where the food is lubricated by mucus secretions. This makes it easier to pass along to the esophagus where calcium carbonate is added into the mixture. Calcium carbonate is used to neutralize the acids that are formed when the food matter decays. Then, the food is temporarily stored in the crop where they will get mixed together. From the crop, the mixture enters the gizzard where the process officially begins. the muscles in gizzard mixes the mass of food and dirt that has been taken in and is then reduced into a thick paste.Glands from the gizzard's wall then add enzymes to the chemical breakdown of organic matter. The mixture then enter into the intestine where bacteria eats the mixture and releases vitamins, minerals, carbohydrates, and proteins that is needed as absorption for the worm. The last step is when the oil particles are passed all the way down to the worm's anus, where the worm deposits waste called worm cast. Worm cast is just ground up soil that has been enriched, neutralized, and revitalized.