Carolyn Van Den Berg, age 11, of Pella.. Iowa, for her question:
Does a snail have a tongue?
Mr. Slowpoke has a very remarkable tongue called a radula. The name is coined from a Latin word meaning scraper. The snail's radula is a clever gadget, a combination of teeth and tongue in one organ. He uses it as a file or scraper, as the name implies.
As a rule, the snail is a vegetarian. His main diet is leaves, especially old leaves. His favorite dessert is leaf mold. Fungus of this sort is present on most leaves though much of it is too fine for our eyes to see. Mr. Slowpoke, however, can find it with the help of his tentacles. These tentacles are the horns which poke up from his head. They see and smell for him.
When food is located, the ribbon‑like radula comes out of the snail’s small mouth. There are no jaws, for the chewing work is done b;; the remarkable tongue. It acts as a file, scraping and shredding the food. When the food is properly broken up, the snail swallows it down to be properly digested in his little tummy.
The remarkable features of the radula are too small for our eyes to see, But they are revealed under the microscope. The top surface is covered with neat rows of triangular shaped toothlets. There are about 50 rows of them to a quarter inch which means that Mr. Slowpoke has several hundred of these toothlets. There is a microscope picture of the upper surface of the snail's radula in your encyclopedia.
Snails and slugs belong‑ to the animal class Gastropoda, meaning the stomach‑footed ones. These sluggish little slowpokes each have a foot as remarkable in its way as the radula. It reaches the entire length of the stomach, which is why the snail is called a Gastropod.
You can study a snail's foot without the use of a microscope, though a lens or magnifying glass is a help. Lift the snail gently by his delicate shell and place him on a sheet of glass.
Place a moldy leaf off to one side and watch from below the glass.
Off he goes towards the food, snaffling along on his stomach‑foot. Watch to see how the muscles of his foot work to inch him along. You can also clock the speed of a snail's pace. Notice too how he leaves a slippery trail behind him. This goo is given off by glands in the foot. It provides a slimy surface to make it easier for him to glide along.
The snail is a small and humble animal but, like all Mother Nature's children, he is well fitted for the life he leads. In some respects ho is better fitted for life than we are. For example, when the human body loses an eye, it cannot grow a new one. The snail's eyes are at the tips of his two longer horns. When he loses one of these eye horns he can grow a new one, eye and all. He can even regrow both of them.