Terrestrial snails are an interesting group. I have to admit that I had a certain ignorance about them. In fact, I did not realize there were significant numbers of terrestrial snails in Iowa until I was an adult. Of course, there is a lack of good guide books that deal with land snails--I am not aware of any that are currently in publication right now.

I have photographed a number of Iowa's terrestrial snails and have located a few sources of information about them. I understand a lot more about them than I used to. However, it still seems that the more I find out about them the more I understand that I don't know.

A great number of Iowa's snails are very small--in the range of one to three millimeters in shell length. The differences between some of them are very subtle.

We have a small pad of cement in our yard. I have found several species of snail in that area, sometimes in the open after a rain, and sometimes under pieces of wet wood. It seems that some days there are fairly high numbers and other days there are none. Sometimes the days with many snails seem identical to the days with none. I don't know what causes the difference, and I have searched long and hard to find snails on the days when they don't seem to be present. They must be somewhere but I can't find them.

I have put together a list of Iowa's terrestrial snails, based on searchable museum database records, NatureServe Explorer records, and range maps from Hubricht (1985). By my tentative list, Iowa has about 130 species of terrestrial snails.

One thing that might be worth noting is the position of the eyes on these two terrestrial snail species shown. They have two pairs of tentacles, and the eyes are on the very tip of the uppermost pair. Almost all terrestrial species have this arrangement, and none of the aquatic snails do. Most terrestrial snails belong to the order Stylommatophora, which is a group of lung (Pulmonata) snails. Pomatiopsis lapidaria, which is shown on the aquatic snail page is usually considered a terrestrial snail by terrestrial snail experts. It is a gilled snail. One species, Hendersonia occulta is a "Prosobranchia" or gilled snail and is undisputedly a terrestrial snail.

I plan to add pages for a few snails to give a little more in-depth information and possibly some photographs. I do this with the caveat that I am not an expert--I key these things out to the best of my ability. I appreciate feedback from anyone who can point out my errors.

Here is my list of Iowa's terrestrial snails. There is still quality control work to be done on it, so there will likely be some changes.