The Odd Couple: An Unlikely Relationship Between Snakes and Crayfish

A digger crayfish (Creaserinus fodiens), one of the few species of burrowing crayfish found at the Ojibway Prairie Nature Reserve.

Since graduating two years ago from Fleming College, I have worked hands-on with a lot of different species including turtles, birds, rodents, and many different plant species. But as Field Tecnhician on the Ojibway Prairie Reptile Recovery Program in southwestern Ontario, this is the first time I’ve been able to focus on conservation efforts for one of my favourite groups of animals – snakes! Little did I know that this work was going to end up including decapods as well, coincidentally another one of my favourite groups.

Everything in an ecosystem is interconnected – sometimes in ways you would never expect.

At the Ojibway Prairie Provincial Nature Reserve, crayfish and Massasauga rattlesnakes have a very interesting relationship. In this region of Ontario, where temperatures drop below freezing for a good part of the year, for snakes to survive it is vital that they have a place to overwinter below the frost line. Deep rock fissures, old wells, or even spaces around tree root systems can all serve as underground areas, or hibernacula, for snakes to sleep the winter away. For Massasauga rattlesnakes, however, their choice of hibernaculum is often crayfish burrows.

You might not typically think of a prairie as a good place to find an animal with gills, but the Ojibway Prairie is actually home to a few species of terrestrial crayfish. Digger crayfish (Creaserinus fodiens) and devil crayfish (Lacunicambarus diogenes) are both found in Ontario, with digger crayfish being the predominant species at Ojibway Prairie. If you are lucky, there is one other species of terrestrial crayfish you might find, called the painted mudbug (Lacunicambarus polychromatus). The first reported sighting of this large crayfish species in Canada was found right here in the Ojibway Prairie Complex in 2016. All three of these species create deep burrows, which can descend deeper than 50 cm below the surface to reach the water table, and can be simple or complex with multiple entrances.

These mud ‘chimneys’ often mark the entrances of terrestrial crayfish burrows.

Aside from their role in creating snake hibernacula, crayfish serve numerous other functions within their environments.

• Crayfish are voracious scavengers and opportunistic omnivores.
• They are important predators and are even considered keystone species in some ecosystems.
• They are both primary and secondary consumers, as well as prey for larger carnivores such as raccoons.
  
• Their place in multiple trophic levels, (multiple positions in the food chain) means they play an important role in the flow of energy through the food web.
• They act as natural indicators of environmental pollution in freshwater ecosystems, and are one of the 27 groups of animals collected in benthic invertebrate sampling for aquatic monitoring in Ontario. They may be small, but these little creatures pull their weight!