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Parastacoides tasmanicus WCT (Family Parastacidae)

Distribution:

This species is endemic to the central western region of Tasmania, around Macquarie Harbour. (TAS).

Features:

Compared to other species in the same genus, this species of crayfish has very small eyes and a very short, broad rostrum. The carapace is relatively wide and setae (hairs) are present in the edges of the cervical groove. They are usually a dark brown to olive green in colour.

Ecology/Way of Life:

This crayfish prefers wet habitats, and its burrows are usually found in waterlogged plains, and rarely on the drier slopes. It is also found in streams and creeks. Like other crayfish in this genus, the burrows of this genus of crayfish support a suite of other animals, known as the pholeteros. Some burrows may contain as many as twenty other species, mainly other crustaceans such as copepods, amphipods and isopods, worms and insect larvae. The burrows provide an important refuge for these animals in times of extreme cold or drought. In summer, much of the surface water in the buttongrass plains dries up, and the crayfish burrows may provide the only source of water in the region. Conversely, in winter, much of the surface water may on occasion freeze, and the water in the deeper burrows may provide the only free water available. The vegetation in regions occupied by these crayfish includes eucalyptus scrub, wet forest, melaleuca scrub, and rainforest. The vegetation is the main food source for these animals; they eat semi-decayed wood, leaves, detritus and some animal matter.

Females moult and produce young only every second year. There is some variation between species in this genus, however mating and spawning generally occurs between autumn and spring, and females carry the eggs from June to November. The eggs hatch in early summer, and the young remain attached to the female through two moults. The young are released in late summer and remain in the female's burrow system until her next hatchlings are released.

Recent research suggests that this is a very ancient species, first appearing during the Miocene (more than eight million years ago). The species, along with others in the genus, has therefore been able to survive through the ice-ages associated with the Pleistocene that had severe impacts on the climate of Tasmania.

Interaction with Humans/Threats:

Large parts of the range of this species lie within the Tasmanian World Heritage Area, and the species is therefore well-protected. It is unlikely that the burrowing crayfish provided an important food source for Aboriginal people. As animals in this species are burrowers, relatively slow-growing and reach a maximum size of only 80 mm, they are not suitable for aquaculture.

Other Comments:

Variations within the species are yet to be formally described. Refer to Hansen and Richardson (2002).

Further Reading:

Crandall, K.A. & Fetzner, J.W. (2004). Crayfish Home Page. http://crayfish.byu.edu/

Horwitz, P. H. J. and Knott, B. (1991). The faunal assemblage in freshwater crayfish burrows in sedgeland and forest at Lightning Plains, Western Tasmania. Papers & Proceedings of the Royal Society of Tasmania 125.

Hansen, B. and Richardson, A. M. M. (1999). Interpreting the geographic range, habitat and evolution of the Tasmanian freshwater crayfish genus Parastacoides from a museum collection. In: W. Ponder & D. Lunney, (eds) The Other 99% – the Conservation and Biodiversity of Invertebrates. Transactions of the Royal Society of New South Wales, Mosman. pp 210 – 218.

Hansen, B., Adams, M., Krasnicki, T. & Richardson, A. M. M. (2001). Substantial allozyme diversity in the freshwater crayfish Parastacoides tasmanicus supports extensive cryptic speciation. Invertebrate Taxonomy 15:667 – 679.

Hansen, B. & Richardson , A.M.M. (2002). Geographic ranges, sympatry and the influence of environmental factors on the distribution of species of an endemic Tasmanian freshwater crayfish. Invertebrate Systematics. 16(4) pp621 – 629.

Acknowledgments:

Text and distribution map by Brita Hansen. Photography by A.M.M. Richardson.

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