Giant Spiny Crayfish

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

They are endemic to Australia. They may be found from near sea level to as high as 1,200 metres (3,900 ft). They are distributed over a range of 55,000 square kilometres (21,000 sq mi).

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.

Mating takes place in winter when temperature drops to as low as 15 °C (59 °F), 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 centimetres (4 in) on maturity while females take about 8 years and grow to lengths above 14 centimetres (6 in). There is a class of "precious males" that mature at 4 centimetres (2 in) length. There are slight variations in reproduction cycle between species in different river systems.