Researchers have found fish-eating spiders across the globe.
Only recently have scientists discovered that spiders do not prey exclusively on insects and may sometimes dine on small vertebrates, a PLOS news release reported.
Semi-aquatic spiders can swim and even dive; these spiders may sometimes supplement fish for insects or vertebrates. These spiders are equipped with powerful neurotoxins and enzymes that allow them to kill and digest fish even larger than themselves.
A new scientific review found these spiders live on every continent in the world except for Antarctica. They tend to do the majority of their fish kills in warmer seasons. They are especially prominent in the North American Florida wetlands.
The study authors identified as many as eight spider families that contain members that catch fish. Spiders that fish often adopt a "sit-and-wait" strategy in an effort to save energy, Live Science reported.
"The spider typically assumes a position near the water's edge, with the rear pair of legs anchored to some vegetation or wood or rock, and their three front pairs of legs out of the water's surface," ecologist Brad Pusey, of the University of Western Australia told Live Science.
When a part of the fish, such as the fin, brushes up against the spider's front legs it immediately attacks, injecting its poisonous neurotoxins into the base of its head.
"It can take many minutes for the fish to die, and it is probably safer for the spider to haul it out of the water to aid in handling and reduce the potential for escape," Pusey said.
Fish are an especially good catch for arachnids; most of an insect's weight comes from its exoskeleton, which is not useful to spiders as an energy source. Fish are mostly made up of nutritious muscle and tend to be twice the size of the spider.
