“The red crayfish”- this is one of the most popular crayfish, red-swamp crayfish (Procambarus clarkii). It is the most wide-spread crayfish in the world as well as in the USA. (Photo: Sujan Henkanaththegedara).
How many crayfish species occur here in the United States? Many people will say the red kind, the blue kind, the green kind and the brown kind…some may add a few more such as the green and brown kind and the red and brown kind.
Although the USA is the global hotspot for crayfish diversity and they are virtually everywhere in southeastern US, it is surprising how little general public knows about crayfish (except crayfish as a food!). North America harbors more than 80% of global crayfish diversity (385+ species) which is mainly concentrated in southeastern United States. Virginia has about 28 species excluding some potential new species.
One of the challenges of crayfish identification is they all look very similar. Typical identification process considers the habitat and morphology focusing on claw shape and size, carapace shape and structure, distribution of spines and tubercles together with color patterns. However, if you want to be certain on the identification of a crayfish species, you need to find a type I (reproductively active) male to look at their genital (gonopodia) morphology.
So next time you find a crayfish in your creek or lake, have a closer look!
My research students David Conner, Connor Perry and Ethan Armistead (from L to R) sampling crayfish from mesocosms.
Yes, these are cattle tanks. But we are not allowed to raise cattle at Longwood University. Also, we are not calling them cattle tanks. We call them “mesocosms”. We are using these cattle tanks to conduct field experiments. You can create mini-ecosystems in these mesocosms and study species interactions under semi-natural conditions. We are currently studying interactions between native Piedmont crayfish and invasive virile crayfish under various densities of invasive crayfish. Invasive crayfish could pose negative impacts on natives due to predation and competition for limited resources. It is a lot of work to set this kind of experiments, but the data will be more realistic and reflect long-term impacts of these species interactions. Let’s see what we get in a few weeks!
During the first eight weeks of this summer, I conducted some interesting research on interactions between native and invasive crayfish. The PRISM program allows Longwood faculty and students to conduct original research in STEM fields. My lab was so fortunate to recruit two Longwood students dedicated for research, James Wilson and Patty Hale. Over the 8-week period we surveyed many local water bodies for crayfish, conducted laboratory microcosm experiments and field mesocosm experiments to understand how native and invasive crayfish interact with each other. The most interesting find is that invasive species impact is not uniform- the impact is determined by the specific crayfish species interacting with each other. One invasive species may truly harm the native species, but another invasive species may not. Stay tuned for more information on experimental results.
We have collected one of our invasive crayfish species, red swamp crayfish from Guion Pond at Sweet Brier College. From left James Wilson, Patty Hale and Johnny Leder.