A Eurasian spider, Argyroneta aquatica (family Cybaeidae), which lives entirely under water and spins a ‘diving bell’ web, which it replenishes…

any of numerous mites adapted to living in water, typically acting as predators or parasites of other aquatic animals, esp. invertebrates.

†(a) a biting or bloodsucking parasite found in marshy areas (probably the larva of a trombiculid mite) (obsolete rare); (b) = water mite n.

either of two Eurasian spiders of the genus Dolomedes (family Pisauridae), the largest in Europe, which frequent pools and swamps and catch insects…