Identifying Freshwater Crayfish in South West WA

Identification

Use this handy key to help identify trhe species of Freshwater Crayfish you have found. Find out how to use this key here.

A Key for Freshwater Crayfish in the South West of WA
1a	Five obvious keels on the head. Small spines present on rostrum	Go to 2
1b	Four keels on the head but usually only two keels are obvious. No spines present on rostrum at all	Go to 3
2a	Two small spines on the telson, located about halfway up. Three pairs of small spines on rostrum.	Marron (2 species) Go to 4
2b	No spines on the telson. Two pairs of small spines on the rostrum	Gilgie (2 species)
3a	Chelipeds (claws) are oval in shape and quite broad	Koonac (2 species)
3b	Chelipeds (claws) elongated and quite large. Obvious hairs on the inside of the “elbow”	Yabby (2 species)
4a	Middle keel extends all the way to the cervical groove. Head covered with short hairs.	Margaret River Hairy Marron
4b	Middle keel does not extend to the cervical groove. No hairs on head	Smooth Marron

Guide to using the key

The key is very simple to use. Simply start at point 1 and read the two choices you have. Decide which of the choices fits your crayfish the best and look to the right of the description. If it provides a number, then go to that numbered point and again read the choices. Alternatively, if a name is provided, then congratulations, you have matched your crayfish to the likely species!

For example, your crayfish has four keels on the head and no spines on the rostrum. Starting at section 1, this description fits best with point 1b. After point 1b it says, “Go to 3”. So you read section 3 and agree with 3b, that the claws are elongated and quite large and that there are obvious hairs on the inside of the ‘elbow'. To the right it says “Yabby”. Therefore, you have successfully identified a yabby. Try the key yourself next time you see or catch a crayfish..