According to the Indiana Department of Natural Resources there are eight invertebrates in Indiana that are considered to be invasive. These are channeled apple snail, Chinese mystery snail, fishhook water fleas, New Zealand mud snail, spiny water fleas, zebra mussels, asiatic clam and rusty crayfish. Except for the last two, if you find any of these the DNR would like to know where. So let’s cover some of these.
The channeled apple snail is unusual, simply because unlike most other invasive invertebrates it doesn’t come from Asia; its home is South America. It has ended up as far north as central Ohio. In Indiana it was found in Lake Wawasee (Kosciusko County) in 2002. Just how did it make it up here? It was widely distributed in the hobbyist aquarium industry because they like warmer temperatures and was used to control plant growth. It has a voracious appetite and received a bad reputation. This probably led to its release in non-native areas.
The basic problem is that this snail competes with native species for food. Since it feeds on all types of aquatic plants, it could alter the natural balance of any given water system.
The shell of this snail is spherical and relatively heavy with five to six whorls. The shell opening is large and mostly oval to round; color can vary from yellow to brownish black.
Now onto the Chinese mystery snail (guess where it’s from). To date it is found in 27 states, the only place it’s found in Indiana is in Marion County, in Fall Creek and the West Fork of the White River.
They came to this country via San Francisco in 1892 as a food item. By 1915 they were found in Boston and by 1950 in Florida. A large snail, up to 2 inches the shell is strong and smooth, usually a light to dark olive green. Each shell can have up to seven whorls. These snails also have a “trap door” which they can close up the opening in their shell. The main problem with these snails is that they can carry parasites and diseases, some of which can infect humans.
Next up is the zebra mussel, which gets its name from the dark and light stripes on its shell although not all will have this. Look for a tuft of fibers that grow from the foot. These are used to attach to any hard surface. A native of western Russia, it is now found in 23 states and 88 bodies of water in Indiana including the Ohio River, Summit Lake (Henry County), Geist Reservoir, Brookville Reservoir, Lake Freeman and Lake Shafer.
Because of their ability to attach themselves to objects including turtles, crayfish and boats they can travel and survive in bilge, live wells or bait buckets.
Zebra mussels can filter up to one liter of water per day. They eat the phytoplankton which puts them in competition with the microscopic zooplankton which affects all the higher organisms including the fishes. Because they filter so much water, infested lakes have become clearer; this is not a good thing. Clear water allows sunlight to penetrate to deeper water, which allows more vegetative growth and in turn can get so thick that swimming and boating could be hindered.
Now we have the rusty crayfish. While it is native to the Ohio River Basin which covers the majority of the state, it seems to be expanding its territory by moving more to the north.
They have a brown body and large claws, the claws being grayish-green to reddish brown. They can be found in lakes, ponds, rivers and streams that have debris covered areas. They do not burrow so they need permanent bodies of water.
Rusy crayfish are opportunistic feeders, meaning that they will eat just about anything that is handy. This includes aquatic vegetation, worms, snails, leeches, clams, insects other crustaceans, fish eggs and small fish. They tend to eat twice as much as similar sized native crayfish. They are very aggressive and will fight the smallmouth bass and rock bass that do eat them.
They are most likely to be spread by anglers and the bait industry, and are also sold to schools for classroom projects. Many of these are probably released into non-native areas.