Inside an Earthworm

Emily Clements-Mitcham-PAP Bio-Period 2

Objectives

This poster is meant to show the digestive system of an earthworm, although it also is meant to educate people about where earthworms live, their predators, taxonomy, and basically any other general information.

General Knowledge

Earthworms are herbivores, primary consumers, and prey to many birds, fish, rats, toads, and moles. They have segmented bodies, and instead of limbs, small hairs covering their bodies that allow them to move called setae. These adaptations allow them to burrow through the ground (where they live) faster an easier. They spend most of their time burrowing and eating soil as they do this in order to get nutrients.

Digestive System of an Earthworm

The digestive system of an earthworm consists of mouth, pharynx, esophagus, crop, gizzard, intestine, and anus. The mouth is where the food, or whatever the organism gets its nutrition from (which for an earthworm is soil), enters the body. Then it passes from the pharynx, through the esophagus, to the crop, where the soil is temporarily stored, and then the gizzard, where the soil is ground up. Earthworms lack a true stomach, so after this, the substance is further digested in the intestines (which break down and get nutrition from the soil. Lastly, the waste is expelled through the anus. This system is the way for the earthworm to get nutrition.

The above photo shows where all of the parts of the digestive system are located and how they look

(with the exception of the anus, which is located at the other end of the worm).

The above image shows its entire (dissected) body

and far down, at the tip of the posterior end, is the small opening where the waste is expelled, the anus.

Lumbricus terrestris

The taxonomy of an earthworm (or Lumbricus terrestris) is as follows:

Kingdom: Animalia

Phylum: Annelidia

Class: Clitellata

Order: Haplotaxida

Family: Lumbricidae

Genus: Lumbricus

Species: L. terrestris

Cladogram showing evolutionary relationships

with Phylum Annelidia (the phylum that contains earthworms).

Map of Locations of Earthworms

The light yellow area shows places in the world where earthworms are commonly found.

Human Interaction

In general, human interaction with earthworms is negative for the earthworm. People put all kinds of fertilizers and chemicals into their soils, meaning that earthworms eat all of those chemicals, damaging them, or possibly, killing them. Earthworms are, on the other hand, important to people as decomposers, adding nutrients to soil.

Fun Facts!

  • There are about 2700 types of earthworms
  • The largest earthworm ever found was 22 feet long, although average earthworms can only grow from 9-30 centimeters
  • Worms are hermaphroditic (meaning they have female and male reproductive organs)
  • Worms must constantly have moist skin. If their skin ever dries out, they die
For More Earthworm Facts

click this button if you want to know even more about earthworms

The Giant Earthworm
Here is a video of "The Giant Earthworm", and earthworm found in Australia that is about 6 feet long, and inch in diameter, and can live for up to 20 years.