First lets look up the taxanomy of our Crayfish.
I'll go brief and not really into the sub or super classes and orders.
Phylum :
Adropoda (Segmented Legs + Hard Outer Shell)
eg. insects, crabs, scorpions
Class :
Crustacea
Order :
Decapods (10 legged)
Family :
Astacidae,
Cambaridae (Northern Hemisphere)
Parastacidae (Southern Hemisphere)
Below is an extract from
http://tolweb.org showing the distribution of the 3 family.
We will be focusing on Parastacidae as its where our local available Crayfish are from.
Genus : 14 of them,
Astacoides, Astacopsis, Euastacus, Gramastacus, Geocherax, Virilastacus, Samastacus, Cherax, Paranephrops, Parastacoides, Tennuibranchiurus, Engaewa, Engaeus, Parastacus
Another extract from
http://tolweb.org showing the distribution of Southern Hemisphere Crayfish,
Parastacidae
Figure 1. Distribution of the 10 Australian Parastacid genera (from Hobbs 1988). The Tennuibranchiurus and Engaeus are shown only in the second map on the right inset.
Figure 2. Distributions of the remaining Parastacid genera. Note that there is an overlap of Parastacus and Samastacus in central Chile that is not depicted very well in the graphic.