Saddleback Crayfish
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Saddleback crayfish

Faxonius medius

Crayfish are considered keystone species due to the important role they play in their environment.  By feeding on algae, bacteria, and slowly decaying material, crayfish help purify the water.  Because of this, the presence of saddleback crayfish in stream and ponds is a welcoming sign. 

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Physical Characteristics

  • Coloration is olive-tan with a bold, black band across the back, behind the head and again at the end of the carapace

  • Pinchers are large, broad, and reddish tan in color

  • Four pairs of walking legs, one pair of pinchers, and additional swimmerets

The external skeleton of the saddleback crayfish is made of calcium carbonate.  In order for the crayfish to grow, it must shed this exoskeleton, which it does by first splitting out of the carapace then pulling its legs and tail through.  Crayfish will often ingest the old exoskeleton to help recover some of the important nutrients within it.  

The saddleback crayfish population has not been evaluated by the International Union for Conservation of Nature (IUCN).  As a result, the current status of the population is unknown. 

  • Size

    1 to 2.5 inches (2.5 to 6 centimeters)

  • Diet

    Plant material, algae, and larvae

  • Range

    Ozark region of Missouri, U.S.

  • CONSERVATION STATUS

    Not Evaluated