Species Key

Crayfish are identified to species using several characteristics, including the shape of the claw (chelae), areola width, rostrum shape, presence or absence of spines (hepactic and cervical spines), shape of the male copulatory stylets (modified first pleopods), and the shape of the female gonopore. Color is NOT a good identification feature because it varies between individuals and is often lost if the specimen is preserved in alcohol (as seen in the photos below). For positive identification, larger males should be collected and killed humanely by freezing.

The male’s first set of pleopods change form (from one molt to the next) depending upon the time of year. Form 1 (F1) occurs during late summer/winter when the crayfish are sexually active usually resulting in softer, more flexible tips to the pleopods. Form 2 (F2) occurs in early to mid-summer when the crayfish are not sexually active, resulting in harder, less flexible pleopods.

Below you will find two tables of photos showing distinct characteristics of each species. 

Table 1: Chela, rostrum, and areola parts of Crayfish Species

Table 2: 1st Pleopods and gonopores