A chimney made of mud

I found this interesting mud structure at the edge of a pond. It was made by a crayfish and is called a "chimney." Crayfish are also called crawfish and crawdads and sometimes mudbugs.

The crawfish uses its pincers and legs to excavate small balls of mud as it digs through the ground making a vertical hole. Each chimney is made by only one crayfish. The hole is just big enough around for the crayfish to climb through. Each ball of mud is placed beside the last in a circle around the hole. Layer upon layer is stacked, creating a hollow crayfish chimney.

Usually the hole will be deep enough that it reaches below the water table providing an element of safety for the crayfish. During times of drought the crayfish will dig deeper and may even close off the top of the chimney with mud. Closed crayfish chimneys are thought to be a sign of impending drought.

Crayfish need water to live in. They are related to the lobsters that live in the ocean.

Through the Woods is a weekly nature photo column by Aaron Horrell. Find this column at semissourian.com to order a reprint of the photo. Find more work by him at the Painted Wren Gallery.