Crustaceans of Iowa

I am not aware of any list of Iowa's crustaceans. However, there is one for Illinois. The list for Illinois includes 207 species, including an estimation of 43 species of water fleas. In the photo to the right, the creature on the upper right-hand quadrant is a water flea. One of the famous ones, which is common and used in science labs every where is Daphnia magna. Identifying this group requires microscopic examination and is impossible with this photograph. The organism in the background--on the left side of the photograph--is an aquatic snail.

Illinois extends much further south than does Iowa, and although much of Illinois is similar to Iowa in habitat, there are areas that are much different. As a result, Illinois probably has more biological diversity than does Iowa. Comparing groups that are known, I would estimate Iowa's numbers of species to be approximately 3/4 to 4/5 the size of those of Illinois. Therefore, Iowa probably has about 150 species of crustaceans.

Turn over any log in Iowa and you are likely to encounter this creature (lower left hand photograph). This is the European sowbug, Oniscus asellus. This is one of two terrestrial crustaceans frequently found in Iowa--the other one is Armadillium vulgare. These animals are commonly called woodlice. As common as they are you might think they are native, but they are not. They are invasive species from Europe. In fact, about a dozen non-native woodlice have found their way to the United States, with the two mentioned being the predominate ones.

With the woodlice being so common, one would assume that they would be harmful to the native organisms. They probably are, but exactly how and how much would be hard to say.