Have you seen a snail sliding along a sidewalk on its muscular foot? Snails are fascinating invertebrates that carry their home, a spiral shell, with them as they move. Their shell provides them support and protects them from predators.
Snails can be found all over the world in deserts, forests, rivers, lakes, oceans, gardens, and even in artic climates. They are classified in the phylum Mollusca —which they share with octopuses, clams, and other types of soft-bodied invertebrates—and class Gastropoda, which they share with slugs. The word gastropod comes from Greek and means “stomach foot.” The foot of the snail is used for movement and support, and it lies under its belly, hence its name.
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How do snails eat?
Snails have a unique tongue-like structure called a radula. In Latin, radula means “little scraper.” The radula is lined with thousands of microscopic teeth which scrape and tear food as the snail moves over the food.
Snails are heterotrophs, which means that they eat other plants or animals for their energy and nutrients. Snails can be placed into four groups of heterotrophs based on what food they consume. These groups are detritivores, herbivores, carnivores, and omnivores.
Snails that are detritivores
Terrestrial snails that are detritivores (decomposers) consume food that you may see in a yard, for example, lawn clippings, branches, sawdust, moss, and leaves. Manure, sludge, dead animals, and insects may also be a meal.
Snails that are carnivores
Aquatic carnivorous snails will prey on small shrimp, starfish, worms, insects, and other snails. An example of a carnivorous snail is in the moon snail (Family: Naticidae). This predator attaches to a clam and releases hydrochloric acid and enzymes to soften the prey’s shell. Once the shell is softened, it uses its radula to form a hole and get inside to eat the meat. Moon snails are also cannibals and will eat other moon snails.
Carnivorous land snails get their energy from slugs, earthworms, insect larvae, and insect eggs. The carnivorous Powelliphanta snail is found New Zealand where it eats slugs and grows as big as a fist.
White-lipped snail (Cepaea hortensis), Cumnor Hill, Oxford. Attribution, Credit: Wikimedia/Charles J. Sharp
Snails that are herbivores
Aquatic snails that are herbivores consume algae and water plants. If you find holes in a water lily, a snail may be eating it for sustenance.
The diet of an herbivorous snail that lives on land consists of garden veggies like cabbage, cucumbers, spinach, kale, berries, and other fruits. They can be seen eating bark and mushrooms.
Snails that are omnivores
Aquatic snails that are omnivores can be found skimming along and eating small dead fish and insects, duckweed, decaying plants, algae, and water lettuce.
Omnivorous snails living on land eat dead animals, worms, and other snails as well as leaves, vegetables, and flowers. They can quickly decimate garden crops.
All the snails need calcium
Snails require calcium to build strong, protective shells. Without calcium, their shells are brittle and prone to breakage. To grow a larger shell, the snail will secrete calcium carbonate through its skin. When a snail hatches, it must find foods that contain calcium to successfully grow and survive.
Glossary
Invertebrate: an animal without a backbone
Heterotrophs: organisms that eat other plants or animals for energy and nutrients
Herbivores: organisms that feed on plants
Detritivores: organisms that feed on dead and decomposing organic matter
Carnivores: organisms that eat meat, or the flesh of animals
Omnivores: organisms that consume plants, animals, algae, and/or fungi
Radula: a structure that mollusks use for feeding that is similar to a tongue and covered with microscopic teeth
Calcium: the fifth most abundant metal in the Earth’s crust. Calcium is essential to all living things, particularly for the growth of healthy teeth and bones.
Terrestrial: living on the land
Aquatic: living in or near water
Hydrochloric acid: a strongly corrosive acid
Enzyme: a biological catalyst that speeds up the rate of a chemical reaction
Cannibal: an organism that eats another member of the same species
Sustenance: nourishment supporting life, such as food and water
Calcium carbonate: a non-toxic and odorless compound commonly found as a white mineral which occurs naturally in chalk, limestone, and marble