Saturday, June 19, 2010


So you thought a crayfish was simply a crayfish?  Alas, there are 315 species in North America!  Many of these species exist in individual cave systems or in single creek systems, but that is still some variety!

This week, we set the minnow traps in the swamp behind the outdoor classroom in an attempt to identify the crayfish species resident at the Audubon Center at Francis Beidler Forest.  Although crayfish have been studied throughout North America, it has not been easy for us to identify our crayfish.  First, we needed to find a key to crayfish identification.  We found a key on the Internet and know that the crayfish we captured are in the genus Procambarus.  Unfortunately, there are 176 species in the Procambarus genus and species identification requires close inspection of anterior (seen as white in image) pleopods, which are only on the male crayfish and are used as claspers for mating.  Additionally, the key is applicable only to breeding males, so juveniles or non-breeding males remain anonymous.

In the end, being able to identify the species of crayfish in Four Holes Swamp is not as important and being able to find plenty of crayfish in the swamp.  Crayfish are omnivores eating plants, algae, snails, aquatic insects, worms, and dead animals.  Crayfish pass that energy up the food chain when they are eaten by fish, snakes, herons, egrets, ibis, otters, raccoons, owls, and people.  Although crayfish can withstand wide ranges of temperature, salinity, and pH, they are sensitive to a variety of toxins, including pesticides and insecticides.  Therefore, a drop in the swamp's water quality would affect the crayfish population (no matter the species) and subsequently affect the populations of numerous other animals species that feed on the crayfish.

Even if we can only identify our crayfish down to the genus level, they sure are interesting to look at on the macro-lens level!

Images by Mark Musselman

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