To The Ground and Beyond-Earthworms

Elizabeth Tyska-Vu-7th Period Pre-Ap Biology

Objectives From the GROUND Up

Students were supposed to learn about the internal and external anatomies of earthworms and invertebrates, and how the body systems relate to each other while the organism is still living.

BackGROUND Information

Earthworms live in the ground, feeding on dirt, detritus, and decaying plant matter. Earthworms are very low on the food chain, as they are eaten by snakes, birds, invertebrates, and some mammals. The scientific name for them is Lumbricina, with variations in the species depending on where they're from.

The soil they feed on is excreted though their anus back into the environment. Earthworms are very dependent on the attributes of the ecology of the soil they are in. if it is too acidic, or there is not enough nutrients, they will die. The outside of the worm is covered in annuli, which have tiny hairs, called setae, on them that help the worm move through the soil. Earthworms also aerate the soil by moving through it, and provide many vital nutrients to the environment. This is very useful to farmers, who have been known to buy earthworms to improve their soil quality and fertility.

Earthworms have adapted a lot since they first evolved. They do not have eyes or ears, but they are very sensitive to heat, light, and touch. This helps protect them during summer, so they don't dehydrate, and winter, so they don't freeze.

For more information and interesting facts about earthworms, visit the site below.

GROUNDbreaking Digestive System

The common earthworm digestive system consists of first the mouth, or prostomium. This leads to the pharynx, which sucks soil into it and then breaks it down because earthworms have no jaws. After being broken down slightly, the food travels through a relatively long esophagus into the crop. The food particles are stored there for a short period of time, then they are moved to the gizzard, where they are fully ground up by sand and rock particles that have collected in the gizzard. After being fully broken down, food is passed through the intestine, where enzymes break down and digest the food. The intestine covers most of the worm, from segment 19 to the end. The nutrients are absorbed through the intestinal wall by the blood circulating throughout the worm. At the end, there is the excretory system, which releases most of the organic wastes on the surface in the form of castings.

For a video of food moving through the digestive system of a worm, see below. After that, you'll find pictures of the internal and external anatomies, along witha viua of the digestive system.

The digestive system of an advanced worm
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  • "Worm Facts." Worm Facts. N.p., n.d. Web. 05 Apr. 2014.
  • "Earthworm Dissection." Earthworm Dissection. N.p., n.d. Web. 07 Apr. 2014.
  • "Common Earthworm." National Geographic. National Geographic, n.d. Web. 07 Apr. 2014.
  • "Earthworm and Adaptation." Information On Earthworms. N.p., n.d. Web. 07 Apr. 2014.
  • "Some Major Parts of The Earthworm Digestive System." Science Project. N.p., n.d. Web. 07 Apr. 2014.
  • The Digestive System of an Advanced Worm. Dir. Peter Cook. Perf. Worm. Youtube. Peter Cook, n.d. Web. 7 Apr. 2014. <>.
  • "Earthworms." Earthworms. N.p., n.d. Web. 07 Apr. 2014. <>.