Giant Spiny Crayfish
Euastacus spinifer occur widely in the coastal drainages of New South Wales, from the Hastings River system in the north to the Clyde River system in the south. (NSW).
Euastacus spinifer are usually deep green, brown or black with reddish joints and orange or yellow spines. There is considerable colour variation and spine development between the different river systems. Very small juveniles are dark in colour with narrow yellow lines across the back and down on to the sides. Males and females are similar. Their total body length (including the abdomen) is about 240mm; the carapace may be up to 120mm long. When startled the claws are raised and outstretched above the head; adults may back away, but juveniles will attempt a rapid escape by flicking the tail several times.
Ecology/Way of Life:
The Sydney Crayfish lives in small to medium-sized streams with rock, gravel or sandy bottoms and logs and leaf litter present. The banks are often steep and shaded by overhanging vegetation. Some individuals move about during the day in low light conditions (shade, overcast weather) but they are most active at night, foraging in the early evening from sunset until when the moon rises. Juveniles eat the same wide variety of foods as adults, such as leaf litter, water plants, small invertebrates and tadpoles.
The Sydney Crayfish spends most of the day under cover and, although details are not available, individuals are thought to have small home ranges. Males are usually mature when 110 mm long and 5–6 years old; females are sexually mature from about 140 mm in length and 7–8 years of age. They have an annual breeding cycle, with mating occurring in May or June when water temperatures fall below 15° C. Females produce between 265 and 1300 oval-shaped eggs, larger females producing more eggs then smaller females. The eggs are incubated under the abdomen for 3–4 months, before hatching during October. The young remain attached to the swimmerets for 4–6 weeks before release in early summer, when water temperatures are 20–24°C. There is no parental care and some individuals live for 20–40 years.
Interaction with Humans/Threats:
The Sydney Crayfish is one of the most abundant and important macro-invertebrates in the small waterways of the coastal drainages of New South Wales. The habitat changes, due to residential or industrial development in some areas, have caused some splitting or isolation of populations, but this crayfish is not considered to be threatened. Fishing is now regulated and the survival of remaining populations depends on conservation action, especially control of water quality and introduced species or disease.
Merrick, J.R. (1993). Freshwater Crayfishes of New South Wales. Linnean Society of New South Wales, Sydney. 128 pp.
Text and Distribution map by J.R. Merrick. Photograph by J. Cann.
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