Can Worms Smell? Wormy Experiment

Welcome to our third Wormy Wednesday! I've been working with Andrea at No Doubt Learning and Erin at The Usual Mayhem to bring you an extensive worm unit, and man (annelid) has it been fun! We've designed a nice home for our worms, we've experimented to see if worms like wet or dry surfaces, we tested to determine whether they prefer light or dark, and today I'm sharing an experiment that will test whether or not worms can smell!  This idea came from Wild Science TV.

Materials Needed

• Earthworms (ones you found, or nightcrawlers you bought at the store)
• Wormy Science Lab Notebook (free download available at the bottom of this post)
• paper plates
• pencil
• ruler
• Variety of substances to test: we choose apple, soap, and gummy worm, soda (coke zero), and vinegar. 
• water

Getting Your Kids into the "Experimenting" Mood

To get your kids mentally ready for the lab, maybe while observing your earthworm home, begin asking questions about worms' physical features and a worm's ability to smell. Your conversation might go a little something like this, 

We've already determined that, while worms don't have eyes like us, they do see light and dark. So what about their sense of smell? Do they have noses?  What sorts of things do you think they would want to be able to smell? (food) If they do smell, do you think worms like some smells and not other smells? Would you like to test to see if worms can smell? Let's collect some items to test.   

Worm Smell Experiment Procedure

1. Using a pencil and ruler, draw 4 quadrants onto the paper plate. We choose to write on the bottom of the plate since ours had blue flowers on it.   
2. Write a letter to represent the item you will be putting into each quadrant. For us it was "A" for apple, "S" for soap, "G" for gummy worm, and "W" for water. Water is your control, so really you are only testing 3 substances.  

3.  Use water and moisten the surface of the entire plate. Remember worms need moisture. Be liberal in the amount of water you use! You don't want puddles, but really get the plate wet.

4.  Then have the kids rub substances into the appropriate quadrants (great literacy application here, sounds, and letter recognition!) You may want to cut, mush (that's the technical name, ya know), crush, or crumble the substance so they are embedded into the plate well.

5. Because we put our substances on the bottom of a plate, we then turned the plate "inside out" so that our worm would have some walls which would slow them down before getting out of our experimental area! 

Data Collection: Do Worms Smell?

6.  Now, before putting the worm on the plate, have your kids make their predictions about what substances they think the worm will like, and hate into their Wormy Science Notebook.  

7. Then observe the worm's response, putting a smiley face for the quadrant the worm hangs out in the most, and a frowny face for the quadrant the worm hangs out in the least. 

8. Repeat with three different worms, recording data as you go.

9. Also write down any interesting observations. 

Here's two videos to show you how the experiment went for us. 

Interpreting Results: So....Can Worms Smell or Not?

Once you have collected data on three different worms, have your child make some final conclusions. NEVER encourage children to make up results, or to try and make the data help someone "win." Caleb is extremely competitive, and hates to be "wrong." No matter how hard I try, he has trouble seeing that experiment data help us learn, and is not a competition. Oh well, all I can do is keep trying, right?

For us, the results were not conclusive. The worm was not repulsed by anything on our plate. So instead of just putting an answer down, we decided that more testing would need to be done before we could answer the question with more certainty. Therefore, you can see on our science notebook, we put a question mark for what substance the worm liked the least. 

One interesting observation we made was that during our quiet observations we heard the bristles (seate) on the paper plate when the worm moved around! 

As far as the "real" answer...worms do not have noses, and do not smell (or taste) like we do, but they can sense odors and substances through chemoreceptors that are found in their skin, not just near their mouth. However, there are more receptors located in both the head and tail of the worm! So in a (not-so-scientific) way, you could say that worms have "noses" everywhere on their body. I bet some kids will want to test the location of receptors with another set of experiments! If so, please share! :) 

In case you are just joining us, here is the Wormy Science Notebook Download. But be sure to visit the  descriptions of the other labs found within this science notebook by checking out the main Worm Unit page. The main page also contains a complete list of links for the literacy, music, and food activities we have for you.    

Also, Andrea at No Doubt Learning and Erin at The Usual Mayhem have posted their week 3 activities for Wormy Wednesday! Go see what they've been doing with worms this past week!