Inland Freshwater Crab

Austrothelphusa transversa

Inland Freshwater Crab, Austrothelphusa transversa

Common throughout the semi-desert central and northern parts of Australia extending south into the upper reaches of the Darling River System. It is wonderfully adapted to the arid conditions. Individuals make burrows up to a one metre deep into heavy, dense, clay soils in the banks of freshwater rivers and creeks, drainage channels, pools, swamps and farm dams.

During the dry season, or in extended drought conditions of up to six years or more, they plug their burrows with earth and go into a dormant state, living off stores of fat in their tissues. The humidity in the burrows stays high helping the crab to avoid drying out, but it is capable of losing almost a half of its total body water and still survive. 

Around late October to early November each female lays between 100 and 350 large eggs. Freshwater Crabs are unusual amongst crabs in giving birth directly to miniature versions of the adult. These baby crabs can be kept in an arrested state of development under the abdomen of the mother, in a thin film of water, for up to six months, waiting for rain to come. Only when they are released into a pool do they grow quickly to adulthood.

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