Life Span of Garden Snails

Everyone knows that a tree's age can be determined by counting its rings; few are aware that the same is true of a common garden snail. Snails grow rings in their shell as they mature that allow scientists to age them and approximate their lifespan. While modern culture tends to use the snail as the epitome of tardiness--the term "snail-mail" for example--snails were revered by the Aztecs as the incarnation of the moon god.

  1. Identification

    • Small and slow, with a hard shell, snails are quickly recognizable. Most gardens have hundreds of them, and, as a species, they have been around for millions of years. Strict vegetarians, they eat almost any plant available, which makes them unpopular with farmers. They leave a trail of mucus behind them that allows one to track their route.

    Anatomy

    • The suction in a snail's foot allows it to climb.

      Classified as mollusks, snails have a hard outer shell made of calcium carbonate to protect the soft body. The eyes are found at the tips of antennae on the head, with the mouth just below. Snails breath air through a respiratory pore behind the antennae. The foot is a long muscle on the bottom of the snail that contracts to move them forward. A gland in the foot produces the slimy mucous that allows the foot to glide over rough surfaces and also creates the suction that allows the snail to move up and down.

    Habitat

    • Garden snails prefer places that are moist, cool, and dark, and you are most likely to see them on rainy nights. Since they are herbivores, they need access to vegetation. Although they will consume garden crops, they also eat grass, leaves and decaying plants. Moisture is critical to their soft bodies, and in particularly dry summers, some species will move into an inactive state akin to hibernation, plugging their shell with mucus to conserve moisture.

    Life Cycle

    • Snails carry the sexual organs of both sexes; after mating, both snails lay up to 100 fertilized eggs under moist soil. Most of the tiny eggs are lost to elements or predators. Those that do hatch immediately consume the shell of the egg to obtain calcium to strengthen their own shell. If they survive to adulthood, they can live as long as 15 years. Most live a much shorter time.

    Misconceptions

    • Although snails can extend their bodies, they cannot leave their shell.

      Although snails can be a nuisance in the garden, the idea that snails carry disease is false. Their slime is not harmful to humans. Along with the common garden snail, some types of snails are found in the desert and under water as well. A snail does not change shells as it grows. A snail is attached to its shell and will die when the shell is broken.