Cherax destructor

Cherax destructor is commonly known by many names but Yabby or Yabbie are most often used.
The colour is normally, dark brown, green-brown, or blue-black, with variations of these colours. They can grow to a maximum body length of 16cm.
They are very common in slow-flowing or stationary bodies of water such as lagoons and back-waters and flourish when introduced into dams. Yabbies can tolerate very poor water conditions and even long periods of drought. When water is scarce, yabbies can burrow into the ground where it is assumed they remain inactive until water becomes available.
Their diet consists mainly of rotting vegatable matter but they are opertunistic feeders and may also eat decaying flesh, including that of fellow yabbies.
The sex of yabbies can be identified by turning the yabby so that the under-side is visible. The male has gonopores (sexual openings) on the bases of the fifth pair of legs (tail end) and the female has gonopores on the third pair of legs.

References:
Jones, D. & Morgan, G. 1994, A Field Guide to the Crustaceans of Australian Waters, Reed, Chatswood, NSW.

Links:
Yabby (Native Fish Australia)

*Photograph published in Jones, D. & Morgan, G. 1994, A Field Guide to the Crustaceans of Australian Waters, Reed, Chatswood, NSW.