Giant Water Spider

Megadolomedes australianus, family Pisauridae


Giant Water Spider, Pisauridae, Megadolomedes australianus, female Giant Water Spider, Pisauridae, Megadolomedes australianus, female

One of the largest hunting spiders found near water. Tips (tarsi) of the legs highly flexible. Length: Including legs, greater than large man's hand span. Colour: grey to fawn brown with highly variable pattern; either long median band or generally mottled.


Eastern Australia near slow moving freshwater stream and river edges.


Large nursery built only for eggs, constricted high in vegetation beside streams.


Not known. Venom: unknown but effective on small vertebrates so potentially of concern to humans.


Magnificent water spiders that quietly scull on the water surface hunting for insects on the water and fish or frogs below it. The spiders can quickly dive through the surface layer, swim through the water and climb to roots on the bottom for sometime.

Generally gentle.

Their eyes reflect torch light at night.

Main prey: insects and vertebrates including fish, frogs, and probably small toads.

Similar species

Water spiders which are much smaller and do not have the flexible leg tips.

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