FAQs (Frequently Asked Questions about Land Snails)
Q: What’s the difference between a snail and a slug? Are slugs related to snails?
A: Slugs and snails are very close relatives. They both glide along on a muscular foot, have tentacles. Snails have a shell while most slugs have little or no shell, and slugs with tiny shells cannot withdraw their body into it.
Q: Is a snail’s shell its house?
A: The snail’s shell offers some protection from predators and from drying out, but no, the shell isn’t really the snail’s house. The snail seeks places to live that are moist and have food, often under old rotting logs, under stones, in the rotting leaves of the forest floor, and other secretive places.
Q: Can snails outgrow or leave their shells?
A: No. The shell is present from the snail’s early development, is attached to the snail, and grows along with the snail in a spiral shape. A snail can’t crawl out of its shell any easier than you can walk away from your fingernails! The very center coil of a shell is where it began in life, and as the snail grows, the shell grows around and around that center in a spiral form.
Q: What happens if a snail’s shell gets cracked?
A: The snail can repair minor injuries to its shell. The snail’s mantle (the tissue surrounding its organs) secretes the calcium and proteins needed to rebuild the shell. Think of the last time you had one of your fingernails or toenails accidentally break too far down, and your body was able to make repairs.
Q: Are land snails related to the animals that make seashells?
Yes, you could say that land snails are cousins to the snails of the oceans. When you find an empty seashell (the spiral kind, not clam shells) on the beach, remember that it was made by a snail too. Marine snails, as they are called, can breathe underwater, while our land snail friends cannot.
Q: How does a snail eat?
A: A snail scrapes its food, rather than chews it like we humans do. A flexible structure called the radula in the snail’s mouth is lined with neatly organized rows and columns of tiny tooth-like projections. The snail moves its radula over the food, scrapes off bits of it, and swallows. If you listen closely, you can even hear the snail’s radula scraping!
Q: What does a snail eat?
A: Different species of snails have different preferences. Some specialize on mushrooms, while others prefer certain types of decaying vegetation. Some types of snails even eat other snails! And the invasive snails of North America tend to like the same foods that we like – carrots, cucumbers, squash, and lettuces. Those are the ones that can become garden pests.
Q: Do snails do anything for the ecosystem?
A: YES! Snails are very important to the ecosystem because they eat very low on the food web – at or close to the bottom. Snails may eat fungi, rotting leaves, and even soil, which supply the snail with calcium and other vital nutrients. Then in turn, snails become food for many different predators, such as insects, salamanders, snakes, birds, and mammals. The snails provide all these animals with essential nutrients. Snails are such important food to some kinds birds that without sufficient snails in their diet, they are unable to lay eggs that have strong shells and healthy embryos. The baby birds can’t develop properly and die.
Q: Why are snails so slimy?
A: Snails make slime from special glands to help protect their bodies from drying out. The slime also helps the snail to adhere to surfaces as it glides along, and it also protects the snail’s foot from sharp protrusions.
Q: Can snails see?
A: Yes, snails can see. For most North American land snails, the eyes are located at the ends of the two upper (longer) tentacles. In a few species, the eyes are located at the bases of these tentacles. The snails’ eyes are fairly advanced, with lenses that can focus, similar to the lenses in our eyes. While they definitely detect changes in light and large objects, no one knows exactly how much detail a snail can see. If you put your finger in front of the snail’s eye, it sees it and will retract the eye into the tentacle to protect itself.
Q: Can snails hear?
A: Snails have no ears, so they don’t hear. But they probably sense vibrations through their skin.
Q: Can snails smell?
A: Yes, snails have a sense of smell, and in fact, it is their best-developed sense. The lower tentacles (which are on either side of the mouth) stretch out in front of the snail as it moves. These tentacles have olfactory neurons (smell/taste receptors) at their tips, enabling the snail its sense of smell/taste so that it can find food. Snails also use their sense of smell to find their way — they follow the slime trails of their fellow snails as well as their own, in order to stay en route to follow a known feeding are or to return to a safe resting area. There are some species of snails that are predatory and carnivorous toward other snails. They follow the slime trails of their prey, who are often unable to escape. Snails probably don’t see well, and they do not hear at all, so it is arguable that smell is their most important sense.
Q: What can I do about the snails that demolish my flower/vegetable garden?
A: First, understand that the snails that munch your garden are not the same snails that do so much good in the ecosystem. The snails in your garden are more than likely invasive species, that is, they are native to other lands. Most of the invasive species in North America are from Europe. They arrived here with the early settlers by being stowaways on ships. Whenever plants and soil are transported across seas, snails and snail eggs can hitch a free ride! Hence a number of species of foreign snails have established themselves in North America. They tend to eat a much wider range of food than the native snails, and so they can thrive well in many places, unlike the native snails that are habitat specialists and have specific requirements for survival.
There are commercial products on the market that can help eliminate the unwanted snails in your garden.
Q: What is the biggest snail in the world?
A: The African giant land snail! Its shell can measure 12 inches in length, and its body is massive.
Q: What is the smallest snail?
A: There are many very tiny snails. One of the smallest in North America is called Punctum minutissimum, or the small spot, which measures less than 1/16th inch (1.1 mm) across the greatest width of its shell, about the size of a grain of sand.
Q: How do snails survive in the winter?
A: Snails burrow under the leaves and soil and hibernate. Their heart rate slows to where it hardly beats at all, and the snail’s blood contains chemicals that prevent it from freezing, similar to many insects and other invertebrates, and even frogs and other animals. The snail seals the opening of its shell with a thick membrane of mucus for further protection before it takes a long winter nap.
Q: How long do snails live?
A: It is generally thought that that snails live a few years in their natural habitat, but this depends upon the species, predation, human disturbances, and other factors. In captivity, they can live many more years.