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Astacopsis Tricornis

Astacopsis Tricornis

Kingdom:     Animalia
Phylum:     Arthropoda
Subphylum:     Crustacea
Class:     Malacostraca
Order:     Decapoda
Family:     Parastacidae
Genus:     Astacopsis
Species:     Astacopsis Tricornis

Local Name : The Tasmanian Freshwater Crayfish

Habitat : Huon River, Eastern Tasmania, Australia

Water Temperature : 0 - 24 derajat celcius

Size in Natural : 14 Cm / 1 Kilograms


This species is endemic to Tasmania, Australia. It is found in the western half of Tasmania, from the Huon River in the South through the western edge of the Central Plateau to the Gog Range in the North and is relatively widespread (Richardson et al. 2006, Hamr 1990). This species has an estimated extent of occurrence of 28,229 km².

This species is found in rivers, streams and lakes. It constructs burrows in rivers and streams. In addition, it constructs extensive burrow networks in the soft bottoms of lakes (Horwitz and Richardson, 1986, Hamr 1990).

Secondary sexual characters are more numerous in females and perform important functions in spawning and incubation of eggs (Hamr 1990). Females show sexual dimorphism by the presence of cement (or glair) glands in their abdominal segments and pleopods, heavier abdominal setation, elongation and decalcification of uropods, presence of long filamentous oosetae (for egg attachment) on pleopods, broader and deeper abdominal segments as well as greater total length of the abdomen (Hamr 1990). The secondary sexual characters observed in males are greater total weight and larger chelae. Secondary sexual characters are reliable indicators of sexual maturity in females of Astacopsis. The complete acquisition of the full set of these characters accurately mirrors the onset of sexual maturity. Females in the process of maturing can be identified by partial acquisition of some or all of these characters (Hamr 1990). Females mature between 62 and 101 mm carapace length while in males spermatophore production occurs in individuals with a carapace length greater than 37 mm (Hamr 1990).

The male gonopores (or external copulatory structures) consist of a raised genital papillae on the ventral surfaces of the coxae of the fifth pereiopods while the the female gonopores are a pair of oval openings on the ventral surfaces of the coxae of the third pereiopods (Hamr 1990). Female gonopores undergo significant changes at the onset of sexual maturity. These changes consist of increased setation around the gonopore as well as the decalcification of the gonopore cover (Hamr 1990). The setal cover is lost and regained through a moult during the two year reproductive cycle of mature females. The position in the body cavity of male and female gonads of Astacopsis is similar to that observed in other Astacidea. The ovaries consist of a pair of sac-like lobes connected by a single commissure while the testes consist of two cylindrical lobes joined anteriorly by a small transverse bridge (Hamr 1990). The largest collected to date was a male from the lower Gordon River with a carapace length of 14 cm and weighing 1 kg (Hamr 1990).