Snail

The snail is a small, soft-bodied animal that carries a spiral shell on its back. Snails belong to a huge group of animals called mollusks, the same group that includes clams, octopuses, and squid. There are more than 40,000 kinds of snails. Some live in gardens, some live in rivers and ponds, and many live in the ocean.

A snail's body has a head, a muscular foot, and a soft middle part called the mantle. The mantle makes the shell. The shell is made of calcium carbonate, the same material found in chalk and eggshells. As the snail grows, it adds more material to the edge of its shell. The shell grows in a spiral, and most snail shells curl to the right.

Snails move by sliding on their one long foot. The foot ripples in tiny waves from back to front. To help it slide, the snail makes a trail of slimy mucus. This slime is so slick that a snail can crawl across the sharp edge of a razor blade without getting cut. Scientists have tested this. The snail is not fast, though. A garden snail moves about 0.03 miles per hour, slower than a sleeping baby's breath.

Most land snails eat plants. They scrape leaves, fruit, and even soft wood with a tongue-like body part called a radula. A radula works like a piece of sandpaper covered in tiny teeth. Ocean snails eat all sorts of things. Some graze on algae, some hunt other animals, and a few even drill through the shells of clams to eat what is inside.

Snails breathe in different ways depending on where they live. Land snails have a simple lung. Water snails have gills, like fish. When the weather gets too hot or too dry, a land snail can seal itself inside its shell with a layer of dried slime. It can wait this way for months until the rain returns.

Not all snails are the same size. The giant African land snail can grow larger than an adult's hand. The Australian trumpet, a sea snail, has a shell more than two feet long and can weigh 40 pounds, heavier than a bowling ball. The smallest snails are tinier than a grain of salt.

Snails are also important food for many animals, including birds, frogs, beetles, and people. In France, cooked snails are a famous dish called escargot. The next time you see a silvery trail on the sidewalk after it rains, look closely. Something slow and ancient passed by.