Eustacus armatus

Euastacus armatus is a species that has sadly disappeared from the South Australian part of the River Murray. It is not known what has caused the disappearance but it may be due to changing water conditions caused by the introduction of locks, reducing the flow of the river along with many other factors. Despite this, however, the Murray Crayfish is still fairly common in New South Wales and Victoria.
It is the second largest crayfish in the world, growing to about 3kg.

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

Links:
Spiny Freshwater Crayfish (Native Fish Australia)

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