Joann Kortering, age 9, of Hull, Iowa, for her question:

How does a snail move?

     Joann and her family enjoy watching the snails in their fish aquarium    but how the slippery little creatures get around is a mystery to one and all. Some of us are puzzled by how a garden snail gets from here to there. True, he only goes at a snail's pace, but since he has no legs, it is a small miracle that he gets anywhere at all. Actually he has a foot, one large and very remarkable foot. It does the work of walking legs    though at a much slower pace. x 3e There are hundreds of different snails in the world. Some belong to the land, some belong to the water. But every one of them has this most remarkable foot. When scientists chose a name for them, they called them gastropods    a word that means "tummy foot." This is because a snail's foot is also the underside of his tummy, reaching from his chin to the tip of his tail. It acts somewhat like a ski or a surfboard, though it has extra special fittings to move for itself.           

     Actually it glides, inched and pinched along by a multitude of clever little muscles that work as a team. Since the long flat foot must glide along„ it needs a slippery surface on which to slide. This problem is solved by 'a built in kit near the front end of the foot. It has special glands that ooze a slimy mucus material. As the snail inches forward, he slithers smoothly over this slime  leaving a silvery trail behind him. An aquarium snail oozes this goo when he makes his impossible journeys around the glass walls. The sole of the foot is banded from side to side with grooves and ridges. As the snail moves, he skids on the edges of his foot, inching along in miniature waves. This is controlled by sets of muscles. More muscles work to move the body forward in sections. The grooved ridges stretch forward and backward to lift one section forward and support the weight behind it. In this small, clever way, the snail manages to get where he's going, on his gastropod tummy foot. What's more the sole of his famous foot is so tough and leathery that he can crawl safely over the edge of a sharp knife.

     True, he gets there    but not very fast. At top speed a healthy snail can travel about two inches in a minute. At this speed, traveling non stop day and night, it would take him 22 days to crawl a mile. However, old slow poke is never in a hurry. Time does not bother him and he is not interested in traveling. As a rule, an ordinary garden snail never wanders more than a few yards from where he hatched from an egg.

     Fresh water snails do not travel far from home either. Some can breathe under water and also come up once in a while for some air. But their sea going cousins have only gills to take oxygen from the water. Some of them have fancy frills and fins, used for swimming. These fellows hold the gastropod speed records.