Earthworm Exploration

By Clarise Trinh, PAP Bio, Guzman, P4

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Objectives

The objectives of this earthworm dissection are to observe the external and internal structure of the earthworm, learn about the functions and locations of different organs, analyze the different systems within the earthworm, and understand the bodies of higher-level organisms.
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Lumbricus terrestris

Earthworms belong to the phylum Annelida.

Background Information

Earthworms live in soil and have many adaptations to help them. Earthworms have a streamlined shape that helps them move through soil, and a mucus coating that helps oxygen pass through the earthworm's skin. Earthworms move through the ground by sucking in the soil through its mouth, passing the material through its digestive system, using sand in the gizzard to help grind food, and digesting and absorbing that substance in the intestine.

Basically, earthworms eat nutrients in soil and breathe through their skin. They have segments along the entire length of their body and a dorsal and ventral side. Instead of a heart, earthworms have five aortic arches. Earthworms have bilateral symmetry, protostome development, and a coelom (a fluid-filled body cavity).

Earthworms enrich and improve the quality of soil.

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Internal Anatomy

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Earthworm Dissection Lab

Digestive System

The digestive system consists of the pharynx, the esophagus, the crop, the intestine and the gizzard. The earthworm sucks soil into its mouth with the help of the pharynx and this material passes through the earthworm's digestive system. The sand in the gizzard helps to grind the food, and passes the material on to be digested and absorbed into the intestine. The digestive system is related to the circulatory system and the endocrine system. Gland cells in the intestine release fluids to aid in the digestive process, and blood vessels in the intestinal walls help to digest, absorb, and transport the food.

External Anatomy

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Wormy Wisdom

A worm does not have legs, arms, or eyes.

There are about 2700 different types of worms.

In one acre of land, there can be more than a million earthworms.

The largest earthworm ever found was in South Africa and measured 22 feet from its nose to the tip of its tail.

Worms are cold blooded animals.

If a worm's skin dries out, it will die.

Worms are hermaphrodites.

Worms can eat their weight each day.

Earthworm Movement

Common Earthworm - Lumbricus terrestris

Earthworm Birth

worm birth