Water spiders, nursery web spiders, fishing spiders

Code MA539999

A family of labidognathan spiders. A separate family, Dolomedidae, has been proposed for the semi-aquatic genus Dolomedes, but it is not well defined.

Pisaurids, especially those of the genera Dolomedes and Megadolomedes, are the most commonly encountered semi-aquatic spiders in Australia. While no pisaurid genuinely lives beneath the waters surface (only one spider species in the world, Argyroneta aquatica (Agelendiae) does that), all pisaurids depend upon a water habitat, be it fresh, brackish or salt.

Some pisaurids (Dolomedes spp.) dive while hunting for aquatic insects, tadpoles and fish, and all hunting species will capture insects at the water's edge or on its surface (Main 1980; Bleckmann and Lotz, 1987; Zimmermann and Spence, 1989). They are regularly seen drifting or spinning across both moving and standing water, the hairs on the tips of their legs enabling them to tread on the waer without preaking the surface tension. When disturbed, they will dive under water for a long time, 'breathing' the air trapped in the hairs around their spiracles. Pisaurids may become very aggressive when disturbed, and can inflict a painful bite; however, there have been no human casualties.

Brown-spotted Dolomedes species are the most commonly encountered by collectors. Generally they hunt at night, resting by day under branches or stones. Sheet-web weaving species (Dendrolycosa, Inola) are found in mangroves of the Queensland coast, their webs built among tree trunks or rocks (Main, 1976; Main, 1980; Main et al., 1985; Williams, 1980).

Representative genera found in Australia include (Main et al., 1985): Dendrolycosa (also: New Guinea to India), Dolomedes (cosmopolitan), Hygropoda (also: southeast Asia, Venezuela, New Guinea, Madagascar, and central Africa), Perenthis (also: India, Burma, Papua New Guinea, and Japan), and the endemic Inola and Megalodolomedes.

Pisaurids occur in both mainland Australia and Tasmania. Worldwide, they are most diverse in temperate areas (Parker, 1982).

References

Bleckmann, H. and T. Lotz. 1987. The vertebrate catching behaviour of Dolomedes triton (Araneae, Pisauridae). Anim. Behav. 35: 641-651.

Main, B.Y. 1976. Spiders. Collins, Sydney.

Main, B.Y. 1980. Spiders of Australia. Axiom Books, South Australia.

Main, B.Y., V.T. Davies, and M.S. Harvey. 1985. Zoological Catalogue of Australia, Vol. 3: Arachnida: Mygalomorphae, Araneomorphae in part; Pseudoscorpionida; Amblypygi and Palpigradi. AGPS for Bureau of Flora and Fauna, Canberra.

Parker, S.P. 1982. Synopsis and Classification of Living Organisms. McGraw-Hill Book Company, New York.

Williams, W.D. 1980. Australian Freshwater Life: the Invertebrates of Australian Inland Waters. The Macmillan Company of Australia, Melbourne.

Zimmermann, M. and J.R. Spence. 1989. Prey use of the fishing spider Dolomedes triton (Araneae, Pisauridae): an important predator of the neuston community. Oecologia 80: 187-194.