Explore Michigan’s wonderful world of crayfish
A new poster celebrates biodiversity of these freshwater crustaceans.
Crayfish – also known as crawdads, mudbugs, or freshwater lobsters – are freshwater crustaceans found in a wide variety of habitats. Crayfish are important components of ecosystems because they have diverse feeding habits (eating everything from plants and algae to small animals, such as snails and fish), and are important prey for many sport fish, birds, and mammals. They also have relatively long lives (up to a decade or more) and grow to large sizes. Because of these attributes, crayfish have a strong influence on the abundance and distribution of other organisms and occupy an important link in food webs.
For many people, crayfish are one of the most exciting discoveries that can be made while exploring Michigan’s diverse aquatic habitats. They can be found everywhere from ditches and rivers to inland lakes and the Great Lakes. You may have come across them while wading, spotted them while snorkeling, observed them in a home aquarium, or perhaps even collected them for a crayfish boil, but have you ever wondered how many different species of crayfish might be found throughout Michigan?
A new poster explores the biodiversity – or variety of life – reflected in Michigan’s wonderful world of crayfish. Produced by Michigan Sea Grant, this educational poster was authored by crayfish experts Mael Glon (Ohio State University) and Kelley Smith (Michigan State University, Dept. of Fisheries and Wildlife); and was supported by other key partners including Michigan Natural Features Inventory and Central Michigan University.
There are more than 600 species of crayfish worldwide, found in a wide range of colors and sizes. Of these, eight native and two invasive species are known to inhabit Michigan’s waters.
Take a closer look; perhaps you have already encountered some of them:
- Northern clearwater crayfish (Orconectes propinquus): A small to medium crayfish commonly found in a variety of stream and lake habitats.
- Virile crayfish (Orconectes virilis): A large crayfish with blue claws commonly found in a variety of stream and lake habitats. This species has even been caught in the Great Lakes by commercial fisherman in their nets at depths exceeding 130 feet!
- Burrowing crayfish: A group of several species of crayfish are rarely seen because they live underground in burrows. These crayfish are elusive, but you may recognize the mud chimneys they make as they dig their often-elaborate burrows along shores of ponds or lakes, wet meadows, and ditches. These burrows create habitats not just for crayfish, but also for numerous other organisms. For example, species such as the federally threatened Eastern massasauga rattlesnake and larvae (young, juveniles) of the federally endangered Hine's emerald dragonfly rely heavily on crayfish burrows for shelter and reproduction .
- Rusty crayfish (Orconectes rusticus): The medium to large rusty crayfish is native to the Ohio River Basin but has invaded Michigan waterways. This crayfish can be easily distinguished by two red, or rust-colored spots on either side of its carapace. These invaders are now commonly found across Michigan where they have had negative impacts on fish, aquatic plants, and invertebrates including native crayfish.
One of the major threats to native Michigan crayfish is the introduction of invasive crayfish such as the rusty crayfish mentioned above. Another potentially problematic crayfish is the red swamp crayfish (Procambarus clarkii), a crayfish that is not yet widespread in bodies of water in Michigan, but is frequently found in the food and pet trades within our state. One of the main ways that crayfish invade new habitats is when anglers using them as bait release them into the wild. Because of the ecological damage in Michigan that has been linked to such releases from bait buckets, the Michigan Department of Natural Resources has banned the use of non-native crayfish as bait, regardless of whether they are alive or dead. It is legal and fun, however, for fishing license holders to catch crayfish from any body of water open to fishing.
Next time you run across our clawed crustacean friends, take a closer look at this important component of biodiversity found in Michigan’s aquatic ecosystems. You can orrder your own copy of the poster online at Michigan Sea Grant bookstore.
Michigan Sea Grant helps to foster economic growth and protect Michigan’s coastal, Great Lakes resources through education, research and outreach. A collaborative effort of the University of Michigan and Michigan State University and its MSU Extension, Michigan Sea Grant is part of the NOAA-National Sea Grant network of 33 university-based programs.