Euastacus spinifer

Euastacus spinifer  is a species of freshwater crayfish endemic to Australia that belongs to the family Parastacidae.

It was first described in 1865 as Astacoides spinifer by Camill Heller, but has been redescribed many times. The argument for the synonymy of the various names has been accepted.

Appearance
Morphological variation is observed in Euastacus spinifer that originate in different river systems. They are mostly green with reddish-brown joints and bright spines.

Diet
Detritus forms the staple diet of the species but they may also eat small invertebrates and tadpoles. They are also cannibalistic. They are also believed to be opportunistic omnivores.

Life cycle
Mating takes place in winter when temperature drops to as low as 15 C, and eggs are laid in early July. Eggs are carried in the female Pleopods and hatch after an incubation period of 110–140 days. Hatch-lings stay with their parents until early summer. Males mature in 5–6 years and grow to 11 cm on maturity while females take about 8 years and grow to lengths above 14 cm. There is a class of "precious males" that mature at 4 cm length. There are slight variations in reproduction cycle between species in different river systems.

Size
Euastacus spinifer may grow up to 24 cm. Largest recorded weight is  1.8 kg.

Distribution
They are endemic to Australia. They may be found from near sea level to as high as 1200 m. They are distributed over a range of 55000 km2.

Habitat
Creeks and estuaries are their usual habitats. Their habitats are usually shaded by vegetation.

Moulting
Moulting frequency of individuals in the species differs with size: smaller individuals moult up to six times a year while larger individuals moult only once a year. Different sizes moult a different seasons temperature is believed to be the regulating force.