The Illuminated Coelom

We had a solid rain today which let up just as I was getting home. The sun had not quite set, but it was low in the sky, shining sideways across the ground.

As I followed the walkway from the bus stop to my front door, I noticed some things I thought my daughters would like to come outside and see, and determined to ask them when I arrived home.

When I entered the door, I was greeted with the usual enthusiastic, “Daddy!” I responded with an atypical but just as enthusiastic, “Who wants to look at worms?” There was no hesitation: Ann and Sara dropped their toys and ran to put on their flip-flops.

We started by looking for worms and teaching Sara how to take care not to step on them. The former was not hard at all; there were hundreds of them. (The later was much more difficult, especially due to the former.) We looked for the biggest—about eight inches—and for the smallest—less than two inches. We looked for fast movers and slow movers.


We came to one spot where the sun was shining broadside on several medium-sized worms. I have never seen the sun shine on an earthworm before, which is not surprising, given that the critters are most often found during rain or at night. Their skin is actually fairly thin, and the light passing through revealed the partially convoluted intestine inside—the classic tube-within-a-tube arrangement. Now my daughters know the word “intestine,” what one looks like, and that they share some anatomical similarity with earthworms.


Half-way around the courtyard, I used a blade of grass to poke a worm to show how they react. My daughters were impressed by the response: a sudden retraction, coiling, and flipping. They each took blades of grass so they could do it themselves. I asked them to see if there was a different response to poking in the “head” or poking in the “bum.” There was no noticeable difference. I asked what happened if we poked in the middle: the result was a retraction but no coiling or flipping. We observed this in several worms, each being poked in only one location. Perhaps we will publish our results.

One last note: Ann (5) was thrilled by the feel of the worms when she touched them with her finger. Sara (2), on the other hand, refused to use her finger but enjoyed using the grass.