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“Seeing” Without Eyes: Do Earthworms “See” White Light?

based on 10 ratings
Author: Janice VanCleave

Problem: Do earthworms "see" white light?

Materials

  • Scissors
  • Ruler
  • Shoebox with lid
  • Paper towels
  • 10 earthworms (can be purchased at a bait shop)
  • Desk lamp

Procedure

Note: Obtain permission from your teacher to use live animals as part of your project.

  1. Cut 4 inches (10 cm) from one end of the lid of the shoe box.
  2. Moisten a paper towel with water and place it in the bottom of the box.
  3. Position 10 earthworms at one end of the shoe box. Try to separate the worms as much as possible on the bottom of the box. Put the lid on the box so that the opening is over the worms.
  4. Place a desk lamp so that its bulb is 18 inches (45 cm) above the open end of the box. Shine the light in the open end of the shoe box.
  5. Observe the worms for 60 minutes.

Seeing Without Eyes

Results

The worms start crawling around immediately. Some move toward the dark end of the box, and others begin to move under the paper towel. At the end of the 60 minutes, all or most of the worms have crawled away from the lighted area. All or most are in the shaded end of the box. A few may have huddled together under the paper towel near the lighted end of the box.

Seeing Without Eyes

Why?

The opening in the lid allowed white light from the lamp to enter the box. Earthworms do not have eyes to see light, but they move away from areas lighted by white light. An earthworm has a nervous system that responds to different stimuli, such as light. It has a brain at the front end of its body, and a large nerve cord extending the full length of the body. Each segment of the worm has nerve receptors leading out from the main nerve cord. White light stimulates these receptors, and a message is sent to the brain, resulting in the worm moving to a less lighted area.

Let's Explore

  1. Is an earthworm's nervous system sensitive to different colors of light? Cover the open end of the box with colored cellophane. In order to produce distinct colors of light in the box, cover the hole in the lid with four layers of each color of cellophane tested. Science Fair Hint: Photographs can accompany the results of each test, and this information can be used as part of a project display. The testing box without the earthworms should also be displayed.
  2. Is it possible that it's the heat from the lamp to which the earthworm is responding? Remove the heat factor by using a flashlight as the light source (a flashlight does not produce much heat). Prepare the lid by putting a circular hole in one end. The hole should be smaller than the end of the flashlight. Repeat the experiment using only the light from the flashlight for the white light source, and place the layers of colored cellophane under the light to test for responses to colored light.

Seeing Without Eyes

Show Time!

  1. Is it possible for animals to "see" in complete darkness? Some snakes, including boas and vipers, are able to pick up infrared signals from warm objects by a pair of special heat-seeking eyes called pit organs. Discover how these pit organs respond to infrared heat. Display pictures of snakes with pit organs. Find and display a picture taken with special film sensitive to infrared heat.
  2. Bats are able to fly in complete darkness by emitting sound waves that bounce, or reflect, off objects. The reflected sound waves, or echoes, heard by the bat allow it to sense the position and size of objects and, thus, "see" in the dark. This is called echolocation. Explain and diagram how the process works, and find examples of other creatures that use echolocation.

Seeing Without Eyes

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