New Giant Crayfish Discovered in Tennessee Stream

January 26, 2011- Nick Engelfried

It’s a common assumption that in our scientifically enlightened age, almost all plant and animal species have been discovered and catalogued by researchers—at least in highly populated temperate countries like the United States.  However a new discovery from the streams of Tennessee shows scientists are not done discovering new and fascinating creatures even in the US.  Last week researchers from Eastern Kentucky University and the University of Illinois at Urbana-Champaign announced they have discovered a species of crayfish—a freshwater aquatic invertebrate that looks a bit like a small lobster—in the deeper waters of a Tennessee creek.

The species has been given the scientific name Barbicambarus simmonsi, and has been referred to as the “bearded crayfish” because of its long antennae covered in hair-like bristles.  It is notable for its large size compared to other crayfish in the area, and reaches a length of about five inches.  Yet despite its distinctive size and appearance it had until now been overlooked by scientists; because it is sparsely distributed in the streams it calls home, the bearded crayfish escaped detection for years.

Then in 2009 Christopher Taylor, a researcher at the University of Illinois, and Guenter Schuster of Eastern Kentucky University, received reports that a fellow scientist might have spotted a new and comparatively very large crayfish species.  A team of researchers combed freshwater streams from the area where the unusual crayfish had been reported, hoping to find a live specimen so they could verify it as a new species.  At last they found a bearded crayfish hiding under a submerged boulder in Shoal Creek, Tennessee.  A DNA analysis later confirmed that it was indeed a new species. 

The Southeast United States, now known to be home to the bearded crayfish, is also the center of global crayfish diversity.  Worldwide there are more than five hundred species in the crayfish family, and North America is home to more than any other continent.  Most of the US species live in the Southeast, and some are so restricted in their range that they are known only from a few individual streams or underground cave systems.  Because of their limited distribution, these crayfish are especially vulnerable to extinction if the body of water they depend on becomes polluted or otherwise degraded by human activity.

In an example of the remarkable diversity crayfish in the Southeast have attained, the bearded crayfish turns out to be not just a new species—it is closely related to only one previously known species, known to scientists as Barbicambarus cornutus.  This related species is also very large, and is found in the freshwater streams of Kentucky. 

Many people don’t realize that discovering new species is not particularly unusual in the world of field science, especially when it comes to insects and other invertebrates in remote regions of the world.  Scientists catalogue thousands of new species every year, many of them found in the canopies of tropical rainforests or the depths of the world’s oceans.  Around 1.75 million plant, animal, and microbe species are currently known and have been given scientific names.  The number of undiscovered species is probably much larger, with the UN Global Diversity Assessment estimating that more than thirteen million species exist in total.

Even in the United States discovering a new species of invertebrate is not necessarily an astonishing feat.  However finding one as large as the bearded crayfish, and living in a habitat that is neither remote nor unexplored, truly is unusual.  The discovery of this unusual-looking creature is a reminder of how much remains unknown in the natural world around us.

Photo credit: Justin Miller

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