Inside the Worm
- Explain how worms digest food
- Identify the parts of a worm’s external anatomy
Worms are designed to turn dirt and organic matter into that black gold that every gardener wants and needs to grow their bountiful harvest. But how can worms be so effective at turning dirt into gold, especially without teeth? Well, the answer lies in their specific anatomy and the help from the beneficial aerobic bacteria that thrive in a vermiculture system that is in perfect balance.
In the worm bin, microorganisms break down food scraps and organic matter effectively in the presence of the right level of moisture. They take food and microorganisms in through their mouths, mix it with saliva, move it down their esophagus and into the crop where the food is stored temporarily. The partially digested food then passes to the gizzard which grinds the food using specialized muscles and forces it into the intestine where it is mixed with digestive enzymes. What is left undigested at this point exits the worm’s body as worm castings.
Tools & Materials
- Red Wiggler worms
- Magnifying glasses
- Paper towels
Introduction (10 minutes)
Begin the lesson by explaining exactly what compost is and how it is created in the worm bin. Describe worm castings (worm poo) and the value they have to the health of soil in terms of their nutrient density. Then share the rendering of the red wiggler’s internal and external anatomy, describing the function of each part and referencing it by its specific name. Be sure to provide the overview of how food moves through the worm’s body and how each internal part of the anatomy plays a role in the production of worm castings.
Activity (20 minutes)
Pull a small amount of worms from the worm bin and have the students examine them on a moist paper towel using their magnifying glasses. Have them identify and name each part of the external anatomy as they can. This could be more challenging with the immature worms. Have them touch the worms to identify the feel of the external anatomy and to see how the worm reacts when touched.
Discussion (10 minutes)
What does a worm feel like? What does it do when touched? Can you identify all five parts of their external anatomy? How is a worm’s anatomy similar to ours? How is it different? Are there other animals that produce outputs that benefit the plants in the garden or in nature?
Assessment (5 minutes)
Use the following questions to assess the Students before and after the lesson. Tally the responses of the group in the Assessment Tracking Log for comparison:
- By a show of hands, how many of you know how worms turn food scraps into compost?
- Now that you understand the process, how many of you think you could describe how worms process the food they consume?
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