Crayfish Turrets - Castles made of Mud
When we were visiting Southeastern Texas last week, we would often see strange mud towers rising out of the ground. They were about 2-3 inches tall, and had a central hole of perhaps three-quarters of an inch in them. They looked a bit like the turrets on Medieval castles.
We’d usually see them in areas where the water table was near the soil surface. They were quite numerous in some places. We saw them commonly in meadows, on hiking trails, even in people’s lawns. Sometimes there would be a single tower, other times there would be clusters of towers.
Turret of a Crayfish burrow
The towers were made out of short cylinders of mud pellets, stacked up almost like logs.
Crayfish burrow turret.
Mud Crayfish burrow turret, with my fingers for scale
These towers were built by Crayfish, freshwater Crustaceans that look for all the world like tiny lobsters.
Some species of Crayfish don’t live in ponds and streams, but instead live on land, in water-filled burrows. And some of those Crayfish build tall turrets around their burrow entrances. The Crayfish emerge to forage for food above-ground on wet nights, but spend the days down in their own little subterranean ponds.
The Crayfish have built topsi-turvy versions of Medieval castles, ones where the moat is underneath the castle’s turret.
Side view of another turret. Note that the pellets are smaller, more nearly spherical. Is the shape of the pellet dependent upon characteristics of the soil, such as moisture? Or was this created by a different species of Crayfish?
I read somewhere that Texas has at least 40 species of Crayfish in it, and more than one of these species build these mud turrets. I don’t know why the Crayfish build the turrets, if there’s some advantage to the Crayfish. Or perhaps they just don’t want to carry the mud balls away, so the pellets just stack up and form the turrets?
I imagine each Crayfish burrow is its own little ecosystem, with a variety of other organisms sharing it. I would be surprised if there aren’t some specialized commensals that only live in the burrows with the Crayfish.
I like thinking of the Crayfish underground, snug in their hidden ponds. I wish we had these Crayfish here in Colorado, pretty neat.