Exactly how the spiders catch the fish isn’t quite clear. But some of the fish may simply be unlucky — they get close enough to brush by a spider’s leg and trigger an attack. Death comes through venom, injected through large, piercing chelicerae, usually at the base of the head. Most die within a few seconds to minutes. Larger fish can linger for nearly an hour. To consume its meal, the spider has to find a dry spot (the aquatic arachnids find a pocket of air among underwater vegetation) where it can pump their prey full of enzymes that will digest it.
More than 80 incidences of fish predation by semi-aquatic spiders – observed at the fringes of shallow freshwater streams, rivers, lakes, ponds, swamps, and fens – are reviewed. We provide evidence that fish predation by semi-aquatic spiders is geographically widespread, occurring on all continents except Antarctica.