Quick Facts

Scientific name:  Argyroneta aquatica

Size:  Up to 15mm

Distribution:  Can be found in many parts of the UK, but it has a scattered distribution - possibly because it has been under-recorded in many areas

Months seen:  All year round

Habitat:  Still or slow-moving freshwater with plenty of vegetation

Food:  Mostly small aquatic invertebrates

Special features:  Water Spiders (sometimes called "Diving Bell Spiders") are the only spiders living underwater almost all of their lives.  They construct a silk diving bell amongst aquatic vegetation, and fill it with air by dragging small bubbles down from the water surface.  Once completed, the spider can stay inside it for up to a day.  The spiders live, breathe, feed and mate inside the bell.  They only come onto land to moult or to find new territories.  The young are even born underwater inside the bell.

On land the water spiders have dark grey coloured abdomens.  They could be confused with some other species, but unlike other spiders, if you place them on water they will quickly dive below the surface.  Once underwater, the spiders take on a silvery sheen as air becomes trapped between the hairs on their bodies.

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