The Giant Freshwater Crayfish & its habitat

The Giant Freshwater Crayfish (Astacopsis gouldi) is the largest freshwater crustacean in the world and is unique to northern Tasmania It has been found in most of the northern rivers that flow into Bass Strait, except for the Tamar River, and in the Arthur-Pieman catchment on the west coast Astacopsis is a genus of crayfish endemic to Tasmania There are three species of Astacopsis: Astacopsis gouldi, Astacopsis franklinii and Astacopsis tricornis A franklinii is found in the eastern half of the state and A tricornis in the western part of the state

In contrast, the species of Engaeus, Geocharax, Ombrastacoides and Spinastacoides are small freshwater crayfish with a body length of under 10 cm. Within the genus Engaeus there are approximately 15 known species, 13 of which only occur in Tasmania. Most species of Engaeus are characterised by their ability to burrow. The burrowing crayfish live their entire life within their burrow systems in muddy banks, seepages and peaty areas. Burrows can be simple and shallow or complex and extensive. The distinctive chimneys at the entrances to the burrows are all that most of us will ever see of a burrowing crayfish.

An adult Giant Freshwater Crayfish displaying brown-green coloration.

The Giant Freshwater Crayfish can grow up to 6 kg and up to a metre in length. Its colour can vary from dark brown-green to black or blue. The Giant Freshwater Crayfish can be distinguished from any other Tasmanian crayfish by the ridge running down the middle of the rostrum (the pointed structure between the eyes). Sometimes they may have different sized claws if they are regenerating after having been in a fight. They are very slow-growing and long-lived, with females taking up to fourteen years before they can breed and males up to nine years They can live up to sixty years