Procambarus clarkii (Girard, 1852) also known as the Louisiana crayfish (Decapoda, Astacidea, Astacoidea) inhabit fresh water in marshes, and rivers. They can reach weights above 50g and 12 cm in length. Although native to Northeast Mexico and South central USA, its ability to exploit disturbed ecosystems ha made Procambarus a very successful invasive species throughout the world. In Louisiana and Spain they Procambarus is at the center of a multi-million dollar industry.

For over a century Procambarus has been successfully used in physiology and neurobiological studies (see T.H. Huxley's "The crayfish"). In fact, we probably know more about this organism's nervous system than any other nervous system. It is this wealth of accumulated knowledge that makes Procambarus a perfect organism to use as a starting point in comparative studies.

In our lab we study how the dramatic change in size that this animals undergo during development affects their walking behavior. We also compare forwards-walking in Procambarus with forwards-walking in the spider crabs (Libinia emarginata). The later comparison encompasses kinematic studies as well as skeletal, neural and muscular anatomy.

Procambarus clarkii can grow 500 times in 3 to 5 months. Despite having similar body architecture, the difference in size dictates that an adult crayfish (left) will experience differently water viscosity and inertia than a hatchling (right) whose Reynolds' numbers are much smaller.

Below is a tree of proposed crustacean relationships based on multiple approaches (Martin and Davis, 2001). We show the species we study plus the other brachyuran shown to walk forwards (the soldier crab, Mictyris).