Colorful, quirky and fascinating, crayfish (also called crawfish and crawdads) play a significant role in Missouri's diverse aquatic ecosystems, local economies and heritage cuisines.
Among the largest and most common invertebrates in Missouri's lakes, streams and wetlands, crayfish often appear in densities of around 20 animals per square meter of stream surface area. This abundance, which is greater than almost anywhere else in the world, is good news because crayfish possess many traits that make them critical to the proper functioning of our water bodies. Crayfish are also an important food for more than 200 other animals, serving as the main forage for some of Missouri’s most popular sport fish. Aside from contributing to Missouri's ecological function and natural diversity, crayfish serve industry and culture in the form of fish bait and freshwater seafood. Crayfish feature in Cajun and other traditional cuisines.
Together, this page and the links Crayfish Distribution and Crayfish Species Found in Missouri cover the kinds of crayfish that occur in our state, their distribution and how to identify them. You may also want to consult the book The Crayfishes of Missouri by William L. Pflieger, and some of the other articles published on this Web site.
It can be hard for nonscientists to identify crayfish. The only identification aids available in many states are highly technical “keys” that place heavy emphasis on slight differences in reproductive structures (gonopods) in mature males. Fortunately, Missouri crayfish have more readily observed features that can be used in determining the species. Also, many have definite and quite limited distributions, reducing the number of species from any given area that need to be considered in the identification process.
At first glance, most crayfish look pretty much alike, but closer study reveals that the species differ greatly in size, color and the proportional development of various body parts. These differences are in turn related to the diversity of habits that crayfish have adopted to find food, reproduce their kind and avoid being eaten by predators such as fish, birds and mammals.
Let's compare two species of Missouri crayfish to illustrate these differences. The longpincered crayfish (Orconectes longidigitus) is one of the largest North American species, achieving a length of six inches or more from the front of its head to the tip of its tail. In contrast, the Neosho midget crayfish (Orconectes macrus) rarely exceeds two inches in the same dimension. The longpincered crayfish is olive-tan, trimmed with bright red, and its pincers are dark blue-green, prominently studded with yellow knobs. The Neosho midget crayfish is a subdued mottled brown and black color, without bright markings or knobs.
The difference in build between them suggests the difference between a bulldog and a greyhound: the stout build and short, heavy pincers of the Neosho midget crayfish contrast sharply with the more slender build and long, narrow pincers of its larger relative. The Neosho midget crayfish is bite-sized for any goggle-eye or bass, and it avoids being eaten by burrowing in rocky shoals with its powerful pincers. An adult longpincered crayfish can mount a formidable defense, and boldly prowls the bottoms of bass-laden river pools at night in search of food.
The largest and smallest crawdad species found in Missouri are the longpincer (Orconectes longidigitus, left) and the Neosho midget crayfish (Oroconectes macrus).
The longpincered crayfish feeds on a variety of plant and animal materials, both living and dead - including other crayfish. However, the Neosho midget crayfish is definitely not on its menu, since these two species never occur together naturally. They occupy non-overlapping ranges in the southern Ozarks, with the longpincered crayfish confined to the White River and its tributaries, and the Neosho midget crayfish occurring in the adjacent Spring and Elk River drainages to the West.
Missouri has at least 35 species of crayfish, more than most neighboring states. Our state harbors about 10 percent of the country’s species and seven species that occur nowhere else in the world except for Missouri. Each species of crayfish occurs only in certain natural settings or habitats that reflect its special requirements; the diversity of crayfish that occur in our state results from the many types of aquatic habitats that are found here. Based on their habitats and requirements, crayfish can be divided into four broad categories:
- Crayfish living in surface streams.
- Crayfish living in swamps, marshes and the shallows of ponds and lakes.
- Crayfish living in burrows away from surface water.
- Crayfish living in underground streams.
These categories overlap to a certain extent. For example, some species occur for much of the year in seasonally flooded pools, but burrow into the bottom as these pools dry up in summer.
Content revision: 20090317
