For our first specimen feature post, it seems only fitting that we are launching our #1001jars blog with a post about crayfishes. Why? Because we are cray-zy about crayfish in our lab! Crayfishes occupy a broad, yet patchy global distribution, with more than 660 described species spanning both the Northern and Southern Hemispheres. Nearly 500 species of crayfish are known from North America – organized into 14 genera, (alphabetically) from Barbicambarus to Troglocambarus. The North Carolina Museum of Natural Sciences (NCSM) Non-Molluscan Invertebrate (NMI) Collection contains a few crayfishes. Okay, fine. We have more than a few. With nearly 20,000 lots (where a lot is typically a jar containing one or more individuals collected at the same place and time) and more than 60,000 specimens of crayfishes, the NCSM NMI Collection is home to one of the largest crayfish collections in the world. We aren’t just interested in crayfishes, but also the tiny critters that live on them – stay tuned, we will be revisiting that in a later post. Did you know that as of right now North Carolina is home to about 10% of described species of North American crayfishes?
At this point, more than a few people are probably thinking: “is a crayfish the same thing as a crawdad?” The answer is yes! Crayfishes are known by several different names, including crawdads, crawfish, mudbugs, freshwater lobsters, mountain lobsters, etc. Whatever you decide to call them, our hope is that after reading this post you will see them as more than… well… dinner.
Crayfishes are members of Phylum Arthropoda and Subphylum Crustacea, meaning they are distant relatives of insects and closely related to lobsters, crabs, and shrimps. Like all arthropods, crayfish have a segmented body, jointed legs (and other appendages), and an external skeleton, called, aptly, an exoskeleton. A crayfish can be roughly divided into two main sections: the cephalothorax – which includes the head and thorax, collectively constrained by the carapace – and the abdomen. Crayfishes are decapod crustaceans, meaning ten-footed; they have 5 pairs of walking legs on the cephalothorax, and 5 pairs of smaller appendages (swimmerets) on the underside of the abdomen. Their front-most pair of walking legs are the ones you want to keep an eye on, because they come with a powerful set of pincers called chelae. These claws which, when combined with the pointy “nose” (known as the rostrum), give these crustaceans a slightly terrifying appearance – especially larger species. No worries though. Unless you are a snail (or an aquatic insect, or drowsy fish), your encounters with a crayfish will not be fatal.
Like we said, we are CRAY-zy about crayfish in the NCSM NMI Unit! Our curator, Bronwyn, is an evolutionary biologist whose specialty is all things crayfish (and the little critters that live on them). The vast majority of research occurring in our lab is “focused” on a broad diversity of crayfishes, including Pacifastacus spp., Faxonius virilis (previously Orconectes virilis), Cambarus acuminatus, Cambarus robustus, Procambarus clarkii, and Procambarus braswelli…to name just a few. In reality, we are working with crayfish species from across much of North America on questions ranging from invasion patterns to shifts in body shape over space and time, to identifying species limits and facilitating new species description.
Crayfishes are important in so many ways. Despite playing a central role in many of the world’s freshwater ecosystems, providing a source of income for many through their use as bait, food, or pets, as models for medical uses, and subjects of many a biology class, crayfishes are an often mysterious, and intriguing, group of animals that we are proud to spend so much of our time focusing on. Everywhere you turn in our lab you are likely to see a poster entitled “Crayfish of [insert state name here]”, a jar of crayfish waiting to be photographed or analyzed, or someone glued to a computer screen mapping crayfish landmarks- and we wouldn’t want it any other way!
Thanks for reading our first ever critter feature! Let us know what you think in the comments section below. In the future, we will likely post about specific species of crayfish – and non-crayfish – that we have in our collection and about some of the research projects that are currently underway, but hopefully for now this has given you a small glimpse into our little crayfish-filled corner of the NC Museum of Natural Sciences.
by Andie Woodson and Bronwyn Williams