Angie Zurek, age 12, of Winnipeg, Manitoba, Canada, for her question:

HOW CAN YOU TELL A WORM'S HEAD FROM HIS TAIL?

The earthworm's long body is tapered at both ends and there are no eye catching features to tell which end is which. However, with a little patience plus a small helping of know how you can tell his head from his tail. This information may not seem too important to a human, but it is vital to an earthworm.

Though both ends of an earthworm dwindle to tapering points, the head end is quite a bit thicker than the tail end. After all, it houses his mini brain and his tiny round mouth. We are not likely to find his mouth because it is concealed below an overhanging upper lip. This lip is a sort of finger, used to grasp food. When dining, sometimes you can recognize his head end because a piece of leaf is stuffed partway into his mouth.

Though this small remarkable creature has no nose and no visible eyes, he prefers certain vegetation and has senses to select favorites. For example, when offered celery and cabbage, he selects the celery. When offered carrot leaves and celery, he selects the carrot leaves.

If these clues do not help you tell his head from his tail, maybe you can solve the problem by watching him in progress. Usually he enters and leaves his burrow with his head end in the lead. However, sometimes he withdraws either his head end or his tail end back down his burrow.

In the early morning, around sunrise, sometimes you may catch him worming his way home through the dewy grass. Then you can be pretty sure that his head end is leading the way while his tail end follows along behind. Not only does the earthworm have a front and rear end, he also has a top and underside, a right side and a left side.

Actually his tubular body    is a series, of about 150 circular rings, or segments. On the underside, there are two pairs of little bristles attached to each segment that help him to grip the ground.

Counting back about 30 segments from his thickened head end, he has a puffy brownish collar. This is his egg case, which later forms a cocoon to be left behind on the ground. Every earthworm produces eggs, for each one is both male and female.