Investigation 1 - Meeting an Earthworm

All of the Worm Watch investigations require you to use your sense of sight and touch to gather information about earthworms. We want you to observe the size, colour, clitellum patterns and behaviour of earthworms. At the same time you should be observing the habitats where you find earthworms and comparing them with habitats where there appear to be no earthworms.

Earthworms are segmented with more or less cylindrical bodies. The body is divided into similar parts or segments arranged one beside the other symmetrically along the length of the body. Click on each term on the diagram to learn more about that term or region of the earthworm. In this activity, you will identify the following parts of an earthworm: prostomium, peristomium, body segment, genital tumescences, clitellum, tubercula pubertatis, setae, periproct, You will also become familiar with the following scientific terms: anterior, posterior, dorsal, and ventral.

What You Will Need

• an adult earthworm (visible clitellum)
• Earthworm Anatomy section of this web site
• Key to Reproductively Mature Earthworms Found in Canada
• water to keep the earthworm wet
• two wet paper towels
• hand-lens (optional)

Caution: Handle your earthworms with care and treat them with respect.

Caution: Earthworms do not like light and should be covered with a wet paper towel as much as possible.

What To Do

1. Make a data chart in your science notebook similar to the one shown below. Use this chart to record your observation of the general appearance and external anatomy of an earthworm.
   
   

   Feature	Observations
   Body colour
   Length of worm (cm)
   Number of segments from the anterior end of worm to the clitellum
   Tail region
   Colour of clitellum
   Other observations about your earthworm

   
   
   
2. Carefully place the earthworm on one of the wet paper towels. Cover the worm with the second paper towel.

   CAUTION: Remember to keep the paper towels wet with cool water throughout this activity.

3. Complete this chart by:
   1. describing the exact colour of your earthworm
   2. measuring the length of your worm. To determine the length of your earthworm, allow the worm to freely extend itself as though it was crawling. Use the back page of the Key to Reproductively Mature Earthworms Found in Canada to measure the maximum distance the earthworm covers when completely stretched out.
   3. counting the number of individual segments from the anterior (head) end of the worm to the clitellum
   4. describing the tail region of your worm
   5. describing the colour of the clitellum
   6. recording other observations about your earthworm
      
      
4. Make a second data chart with the following headings:
   
   

   Name Of Part	Description and Sketch of the Part	Location of Part	Function of Part
   peristomium	The peristomium is the first body segment.	anterior end of the worm on its dorsal surface	The peristomium contains the mouth.
   prostomium
   genital tumescence (GT)
   clitellum
   tubercula pubertatis (TP)
   setae
   segment
   periproct

   
   
   Complete this chart by referring to the diagram, the Earthworm Anatomy section of the Worm Watch web site, and the living worm. The first one has been done for you.
   1. Locate each part of the worm.
   2. Describe the location using terms such as anterior, posterior, dorsal, and ventral.
   3. Use the Earthworm Anatomy handout to help you summarize the function of each part of the earthworm.
      
      
5. Return your worm to its container or its natural habitat when you are finished.

   CAUTION: Do not put "store-bought" worms into your garden. It is important not to introduce new earthworm species into soil. As a challenge activity write-down all the exotic insects, plants, fish, birds and animals that have been introduced to your area and describe how they have affected the landscape, other species, and human activities.

6. Wash your hands with warm water and soap as soon as you have completed the investigation.

Key Terms

What Did You Discover

1. Why is it important to observe and describe the details of an earthworm?
2. What part of the earthworm is only found on adult worms?
3. Make a scientific drawing of your earthworm. Pay particular attention to the:
   • colour of the earthworm
   • number of segments between the anterior end of the worm and the clitellum
   • length of the specimen
   • genital tumescences (GT) - make sure to draw the exact pattern of the GT on your earthworm
   • clitellum- pay careful attention to the size, shape, and colour of the clitellum
   • tubercula pubertatis (TP)- make sure to draw the exact shape of the TP and their location on the clitellum
   • setae