Other Classroom Animals

Earthworms | Snails | Pill Bugs and Sow Bugs

Earthworms: have no bones, legs, wings, or hard exoskeleton. In fact, although their bodies are segmented, earthworms are annelids, not arthropods. If you look closely at each segment, you will see that it has four pairs of tiny spines, or setae. The enlarged ring is known as the clitellum: the brain, stomach, and reproductive structures are located to the front of this area. (So, it is not true that if you split the worm in half, you end up with two live worms, since one half would be missing all vital organs!) Interestingly, earthworms are hermaphroditic, i.e. they produce both sperm and eggs. Mating occurs when earthworms exchange sperm; the clitellum produces a mucous band that encases the eggs and sperm and is released to the soil. Within a few weeks, the eggs hatch. To keep an earthworm culture, you will need good garden soil, mulch or rotting leaves, and enough water to keep everything moist. Earthworms are vegetarian, so any vegetable scraps will be quickly consumed. They thrive under relatively cool conditions (50-60 degrees), so you should not worry about keeping them warm.

Snails: these slimy animals are also invertebrates and are characterized by a hard shell; they are grouped among the mollusks. The snail's body is called a foot and it ends in tentacles. The mouth is on the bottom of the head, while all internal organs are inside the shell. Some, but not all snails are hermaphroditic. Egg masses resemble globs of jello which adhere to the aquarium's wall or some other object in the water. Do not put too many snails in any container (3-6 per quart of water is recommended), and provide them with fish food or aquatic plants to graze. Like fish, the snails should never be put in chlorinated tap water.

Pill bugs and sow bugs: these small creatures are also commonly referred to as "rolypolies" and are closely related to lobsters! They have a segmented body with a hard exoskeleton but, unlike insects, they have two pairs of antennae and ten legs (on abdomen and thorax). As their name implies, pill bugs can roll-up into little balls. They are herbivores and feed on decaying plant matter.