About Land Snails
There are over 500 species of land snails in eastern North America and over 125 are likely found in Indiana.
Land snails (and slugs) may be found wherever there is suitable habitat. They are especially abundant in the forest floor, but also found in grasslands and edge habitats, and around human built environments (homes and gardens).
The introduction and spread of non-native snail species occur along with short- and long-term environmental changes. We lack much basic information about the biodiversity of land snails to adequately assess or understand potential impacts.
Where Do You Find Land Snails?
At home or in towns, look in your backyard around vegetation, especially dead grass or leaves, at the edge of rock walls, or around the garden. When you take a walk in the woods, look in the forest floor among leaf litter and in or on or below rotting woody debris. Use your fingers to "rake" the soil and debris. Some may be found climbing a tree or herbaceous plants or around debris at the base of rock outcrops. Grassy areas can be good collecting for some micro-species. Search as many places as you can, since snail distribution is very patchy. Success is greater after rains.
It is OK to pick up shells, but if you pick up live snails, return them to where they came from. You should also sanitize your hands after touching a live snail or slug (a slug is just a snail without a shell). If you keep them for a short while (as in a classroom), be sure to return them to where you found them and to no other place.
In some states, snails may not be collected without a collector's permit and/or permission from the property manager, if state land. Other entities (city or county parks or other types of natural areas) may also require permission. Always check first and inquire.
As well, always be careful in the field and do not tear up the forest floor looking for snails. Be respectful of the habitat and replace bark, stones, leaves, and so on when you have to disturb them to look for snails.
Ecological Roles
Land snails serve an important role in ecosystems. They consume both the living and the decomposing. Land snails may eat fungi growing in or on decaying wood, the wood itself, decomposing plant matter, living plants, or other snails. Yes, a few are predaceous and some harbor parasites. In turn, land snails are prey for a wide variety of reptiles, small mammals, birds, and insect larvae. In the case of the image above, birds preyed on snails from our garden, breaking the shell on top of the trash can lid - followed by a fly feast.
Snails eat by scraping surfaces with a specialized structure called a radula. It is a long strip of tissue with hundreds of replaceable teeth. The radula is drawn back and forth over a surface, scraping food into the mouth.
Several land snails and slugs harbor a brainworm nematode, Parelaphostrongylus tenuis. White-tailed deer pick up larvae from infected snails as they browse. The larvae end up in the deer’s spinal cord, develops further and lays its eggs in the deer’s brain. The new larvae end up in the deer’s feces, where a snail or slug will continue the life cycle.
It's A Snail's Life
Eggs and Young
Land snails start as eggs about 1-2 mm in diameter, usually laid in groups buried in loose soil, sometimes laid singly. There may be a few or up to 24 or more in a batch.
The image above is of neonate Flamed Tigersnails (Anguispira alternata) with unhatched eggs.
The egg nourishes the developing snail at first as it builds the first few coils of the shell (the protoconch). The hatchling crawls out of its egg shell (which it can eat). If the snail does not become prey or fall to an early natural death along the way, it will grow, add more coils (called whorls), and become reproductively mature.
Mating
Land snails are hermaphrodites - one individual produces both egg and sperm. Generally, two individuals will mate and share sperm. Some meet head-to-head and some side-by-side. This pair is the Western Whitelip, Neohelix alleni.
This pair of polygyrid snails below were found mating on a rainy winter day with milder temperatures.
How big are land snails?
How big are land snails? Many land snail species are small - less than 4 mm (just over about 1/8 inch). Tropical species are large enough to hold in your hand.
Photographing Land Snails
If you look at snail posts at iNaturalist.com, most only give one view - the top usually. For the most proper identification of "wider than tall" snails, at least three views are needed, as seen in the species descriptions that follow: top, bottom, and side looking at the aperture. Actually, two separate side views are better – one showing the aperture and any teeth and clearly showing the height and shape of the shell to help determine the type of spire - and one more close directly into the aperture showing the nature of any teeth if needed.
For "taller than wide" snails a front view of the entire snail with the aperture and a closer view of the aperture, if possible, will usually do.
