By Ethan Hatchett
Along many streams and creeks, small structures made of mud litter the ground. These curious formations are often overlooked in favor of watching rushing water or shimmering fish, but they serve as a wonderful introduction to the fascinating lives of crayfish.
Georgia is home to approximately 70 species of crayfish that live in a wide variety of habitats such as marshes, ditches, streams, floodplains and caves.
Crayfish are decapod crustaceans related to shrimp, crabs and lobsters. These freshwater invertebrates come in a variety of shapes and sizes, but few match the beauty of the Piedmont blue burrower.
The Piedmont blue burrower is a striking blue crayfish that grows about 3 inches long and is found only in Georgia. It inhabits burrows along streams and seepage areas that drain into the Flint and Chattahoochee rivers. These crayfish build complex tunnels marked by distinctive “chimney” openings created from piles of dirt or mud pellets. Depending on the soil quality, the chimneys can stand up to 6 inches tall.
Piedmont blue burrowers spend most of their time in their burrows, leaving only to mate and gather food – usually small invertebrates and plant matter.
Mating is thought to occur during the spring and fall but the timing is not known for certain. Females carry fertilized eggs under their swimmerets, and upon hatching, the juvenile crayfish are attached to the mother by her telson thread, a string-like membrane from the egg sac. It is uncommon for adult crayfish to share burrows, but juveniles will stay in groups with their mother until maturity.
Piedmont blue burrowers exist in only a small range, which makes them more vulnerable to extinction. Seemingly minor changes in the landscape and alterations in water quality can substantially impact their remaining populations.
This precarious status has contributed to the crayfish being state-listed as endangered (although with limited protections). It is also a high-priority species for conservation in Georgia’s State Wildlife Action Plan. This comprehensive, statewide conservation strategy, which is undergoing a periodic revision, lists 640 native animal and plant species as priorities for conserving. The 150 conservation actions recommended in the plan focus restoration and protection efforts where they’re most needed and most effective.
But it’s not all bad news for the Piedmont blue burrower. There are 20 known locations with small populations, including protected locations at the Monastery of the Holy Spirit in Conyers and city-owned property in Warm Springs.
Piedmont blue burrowers are some of Georgia’s most unique crayfish. Their story of persistence also reminds us that you don’t need a calcified spine to have the backbone to survive.
Ethan Hatchett is a communications assistant in DNR’s Wildlife Conservation Section.