Euastacus girurmulayn

Euastacus girurmulayn is a large freshwater crayfish belonging to the family Parastacidae, a group of spiny, clawed crustaceans endemic to Australia's eastern river systems. Like other members of the genus Euastacus, it likely possesses a heavily armored exoskeleton with prominent spines on the carapace and claws, adaptations that deter predators in cold, oxygen-rich mountain streams. As a benthic omnivore, it plays an important ecological role in freshwater habitats, processing organic matter, leaf litter, and detritus, and in turn serving as prey for fish, birds, and other predators.

Its presence is often considered an indicator of stream health, since Euastacus species are highly sensitive to water quality and temperature changes.

The species is restricted to freshwater streams and adjacent forested catchments in Australia, occupying a narrow geographic range typical of many Euastacus crayfish, which have limited dispersal ability and high habitat specificity.

This species is classified as Critically Endangered, threatened by a combination of pressures including illegal hunting and trapping, habitat degradation from logging and forestry effluents, agricultural runoff, and unrecorded pollution sources. Fire and altered fire regimes, compounded by temperature extremes potentially linked to climate change, threaten its cool-water habitat. Invasive species introduce competition and disease risk, while unregulated harvesting for food or the pet trade adds further pressure on already small populations.

Specific population figures are not currently available, and the population trend is listed as unknown. Conservation measures for Euastacus crayfish generally include habitat protection, restrictions on collection, and monitoring within protected forest and catchment areas. Given the convergence of ongoing threats and its restricted range, the species' long-term outlook remains precarious without sustained habitat protection and threat mitigation.