The diving bell spider or water spider (Argyroneta aquatica) is the only species of spider known to live almost entirely under water. It is the only member of the genus Argyroneta.
When out of the water, the spider ranges in colour from mid to dark brown, although the hairs on the abdomen give it a dark grey, velvet-like appearance. It is native to freshwater habitats in Europe and Asia.
The diving bell spider is found in clean freshwater habitats with aquatic vegetation, such as lakes, ponds, canals, marshes and slow-moving streams.
It ranges through much of mainland Europe (no records from Portugal, Greece and Albania), the British Isles and northern Asia (Turkey, Caucasus, Russia, Iran, Central Asia, China, Korea and Japan) up to latitude 62°N.
Most of the range is inhabited by the nominate subspecies, but Japan has its own subspecies, the very similar Argyroneta aquatica japonica.
Their bite is often described as being quite painful to humans and causes localised inflammation, vomiting, and slight feverishness that disappears within a few days.
However, solid evidence is lacking, with information being based on old unverified reports since recent confirmed reports are lacking, leading some sources to refer to its bite as reputedly painful