Earthworm Science

Investigation #3: What Do Your Earthworms Like to Eat?

Do you like to eat green beans and turnips or would you rather eat a pizza? Most of you would likely prefer to eat pizza. Earthworms have similar likes and dislikes when it comes to food. For example, one species of earthworm, Lumbricus terrestris (dew worm), will eat lettuce while other species of earthworm wouldn't touch lettuce. In this activity, you will determine what your species of earthworms like to eat.

Problem

What does your species of earthworm like to eat?

Hypothesis

Write a hypothesis that predicts the type of food your earthworms like to eat. Record your hypothesis is your science notebook.

Materials

• 2 large, clear plastic drinking straws
• 1 large plastic tub (1.5 L margarine container)
• potting soil (from your vermicomposter)
• bedding material (same as used in your vermicomposter)
• water to keep the earthworms moist
• 4 different types of food (each group can use four different food items)
• ruler
• duct tape

• electric drill
• drill bit approximately the same diameter as the drinking straws
• scissors

1. Read the procedure and design a data chart to record your observations. Make sure to include the species of your earthworm on your chart. If you are not sure which species of earthworm you have, go to the section of this web site to learn how to use the classification key and how to identify your earthworm.
2. Do this step under the direct supervision of an adult. Drill four holes into the sides of your plastic tub that will be used to hold the drinking straws. Use Figure 1 below as a guide when drilling the holes.

   
   
   Figure 1: Drilling template

3. Use the scissors to cut the plastic drinking straws in half.
4. Use a small piece of duct tape to seal one end of the straw. This will form a feeding tube. See Figure 2.

   
   
   
   Figure 2: Drinking straw sealed at one end with duct tape.

5. Fill each tube with a different type of food.
6. Insert the food tubes through the holes that you drilled into the margarine container. Secure the food tubes to the plastic tub with duct tape.
7. Take some soil and bedding from your vermicomposter and add it to the plastic tub. Be sure the soil completely covers the food tubes.
8. Place five or six worms into the margarine container. Moisten the soil and place the cover on top of the plastic tub. Make sure there are air holes in the lid of the plastic container. Remember to moisten the soil on a regular basis.
9. Observe your feeding tubes every day and record your observations in your data chart.
10. Return the earthworms to your vermicomposter as soon as you have determined what they like to eat.

1. Which food(s) did your earthworms like to eat?
2. Which food(s) did your earthworms dislike?

1. Go back to your original hypothesis. Did the results of this investigation support or reject the prediction that you made at the beginning of this investigation?
2. Why do you think different species of earthworms eat different types of food?

Repeat this investigation. Keep the most popular food source in one food tube but use three different types of food in other tubes.