General Information about Snails
Snails or gastropods are small to medium sized mollusks that can be found on every continent on Earth except Antartica in almost any wet habitat, especially those with a lot of vegetation. Snails are famous and easily recognized due to their hard, coiled shells. If a snail doesn't have a shell, then it's a slug. Snails are usually herbivorous and eat vegetation like leaves, stems, and algae. Some larger snails are omnivores or carnivores. Snails are easy prey for any animal that can get through the shell, since they're small and slow. As a result of this, snails are eaten by rodents, birds, amphibians, and fish. Snails are hermaphrodites and are neither male nor female and can breed with any other snail of the same species. About a month after mating, one of the snails lays small eggs, which hatch after a few weeks. Baby snails become adults in up to two years. Unfortunately, in some areas, snails are suffering due to pollution, habitat loss, or changes in the food chain. Since this post focuses on aquatic snails, we'll shift our focus to them. Aquatic snails, like their name sounds like, are found in almost any wet environment, in many cases in water. These habitats include ponds, lakes, swamps, ditches, ponds, springs, and slow rivers. Substrates include rocks, sand, mud, vegetation, and decomposing plant matter. There are usually more snails in hard water which contains large amounts of minerals because snails require calcium carbonate to form their shells. Snails usually aren't found in acidic water like bogs, cold water like high mountain streams, or really any water that gets above 30 degrees Celsius. Some species of aquatic snails migrate to better habitats on the basis of temperature. All snails, including aquatic snails, glide on their substrate on a film of mucus that their feet secrete. Aquatic snails rely on oxygen within the water to breathe or periodically come to the surface to breathe. Most aquatic snails feed on algae and other aquatic vegetation or decomposing animal or plant matter.
I did a sketch of the anatomy of a land snail based off of this model.
Voshell, Reese. A Guide to Common Freshwater Invertebrates of North America. The McDonald & Woodward Publishing Company, 2002. Print.