Night Crawler (Lumbricus terrestris) in the Classroom.

Night Crawlers (Lumbricus terrestris) in the Classroom!

By Doug Collicutt

Introduction

Night Crawlers and other worm species make interesting, low-maintenance class room critters. Keeping them alive and healthy for a long time, or on a permanent basis, requires a pretty good sized container or aquarium. If you just want to have some visit the class room for a while, you can get away with a much smaller container, say a 1L jar.

(For some background and basic biology on Night Crawlers, and other worms, check out our Night Crawlers article in this issue.)

Getting Some Worms

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There are several ways of getting Night Crawlers, or other kinds of worms. The way that professional worm pickers get them is to wander around at night, with a flashlight and pail, in the appropriate habitat: farm fields or golf courses; picking up worms as you go. Most of you will probably prefer the other methods, primarily as they doesn't involve nocturnal meandering in strange places. One method involves waiting for rain. Not the slightly-dampening-the-ground rain, but a drenching rain, preferably rain that lasts for a day or two. Worms come out and crawl around on top of the ground when the soil is soaked. If they encounter sidewalks or roads they simply keep crawling and they are easy to see once they've ventured out onto the concrete, asphalt or even gravel surfaces. Then during or immediately after the rain you just go for a walk and pick up worms. Put them into a pail with some moist leaves or a bit of soil, then transfer them to your prepared worm habitat.

Worm Callers! Yes, there are such things, and there's nothing magical or supernatural about them. Although it's not really understood just why they do it, worms will crawl up onto the surface in response to vibrations penetrating the soil. I couldn't find an authoritative statement as to why they should do this, but it's been suggested that they may be trying to flee from large burrowing predators, such as moles, by crawling away rapidly (for a worm) on the surface of the ground. So, a worm calling device can be as simple as a stick plunged into the ground and made to vibrate, either by hitting it rapidly and repeatedly, or by rubbing another notched stick against it. Worms may appear at the surface in a few moments or it may take half and hour. If you give it a try, please let me know the results!

Of course, there is one more rather simple, but totally unchallenging way to get Night Crawlers. Venture forth to your local bait shop and, armed with a "twoonie", buy a bucket of worms.

Class Room Habitat for Worms

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Fill a container with soil from the site where you found the worms, or use garden or potting soil. Use a large glass jar or a small aquarium. It should be something that has a ventilated lid or cover; there needs to be good air circulation, but you do need a secure cover as worms can crawl up smooth surfaces. Adding sand and peat to the soil mix will make it less subject to packing and easier for the worms to get around in. Put a layer of dead leaves or some other mulch on top of the soil to help keep the soil surface moist,otherwise the worms will avoid the drying soil at the surface. For a short stay, that's all you have to do. There should be enough organic matter in the soil for the worms to eat for a couple of weeks. Don't forget to keep the soil in the container damp, but never make it soggy! Add small amounts of water as necessary.

Making their stay worthwhile, however, requires that you be able to see the worms, at least on occasion. The trick to doing this is to have a clear container that you can cover with some sort of opaque covering. Taping black construction paper to the outside of an aquarium or encircling a large glass jar with dark paper will suffice. The key is that you must stop light from penetrating. Worms shun the light. In a natural setting, if they are exposed to light, they are exposed to predators! Set up your worm habitat and cover the outsides, then after a day or two remove the covering paper and you should be able to see the worm tunnels along the inside of the container. With any luck, you will occasionally see the worms themselves crawling along the sides. However, they will quickly retreat from view once they are exposed to the light. Replace the covers and the worms will resume acting like worms. You can check on their progress and activities regularly by removing the covers, but if you fail to replace them the worms will stay away from the lighted sides of the container.

If you intend to keep your worms for a long time, you'll have to add some food. Chop up some small pieces of lettuce or some other plant matter and work these into the top of the soil in your worm habitat. Small amounts of commercial fish food will provide a protein rich supplement.

So, try having some worms in the class room and "get a feel" for some of the living things that are right under your feet!

Thanks for learning about Night Crawlers in the Classroom!


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