Freshwater shrimps

Code OT019999

Decapod crustaceans with a prominent rostrum and the abdomen bearing a tail fan. Eyes on stalks. A carapace completely covers the dorsal and lateral thorax. The rostrum most commonly long, sharp and serrated. Legs long and thin, and without strikingly conspicuous claws (chela). The first two pairs of legs are similar in appearance and bear small chelae tipped with tufts of long setae. Mostly small, transparent, quick-moving animals.

Atyidae live in many types of water body but prefer comparatively still waters where they congregate under banks, large submerged boulders and aquatic vegetation. Most prefer surface-waters but the genus Atya comprises more robust, coloured forms that walk on the bottom.

The Palaemonidae (prawns) differ from Atyidae in having the second pair of legs greatly elongate and ending in rather slender claws. The Parasticidae (crayfish) differ in having the first pair of legs robust and ending in strong claws.

All other shrimp-like animals (Anostraca, Syncarida, some Amphipoda and Isopoda), except Thermosbaenecea, are without a carapace. The Thermosbaenecea have a carapace joined to the head but leaving the thorax free. A single species 1-1.5mm in length is known from a single cave in WA.

Atyidae are distributed in every State but are most common in the eastern half of the continent. The Australian Atyidae are placed in genera Paratya, Atya, Caridina, Caridinites, Stygiocaris, Parisia, Pycneus and Pycnisia. Paratya australiensis is the most widespread species of small freshwater shrimp in eastern Australia. Keys to genera are given by Williams (1980) and Choy and Horwitz (1995).

References:

Choy, S. and Horwitz, P. (1995) A preliminary key to the species of Australian shrimps (Atyidae) found in inland waters. In: Horwitz, P. (ed.) A Preliminary Key to the species of Decapoda (Crustacea: Malacostraca) found in Australian Inland Waters. Co-operative Research Centre for Freshwater Ecology Identification Guide No. 5., Albury, NSW.

Horwitz, P., Knott, B. and Williams, W.D. (1995) A Preliminary Key to the Malacostracan Families (Crustacea) found in Australian Inland Waters. Co-operative Research Centre for Freshwater Ecology Identification Guide No. 4., Albury, NSW.

Williams, W. D. (1980) Australian Freshwater Life. Macmillan Australia, Melbourne.