These semi-aquatic spiders “anchor their hind legs on a stone or plant, letting their front legs float on the water,” the study reads. Then the arachnids wait for their prey. At the slightest movement of the water, or the slightest contact with their legs, the spiders attack.
If they are so careless, it is because piscivorous spiders are general predators; in other words, anything that moves will do. Most of the time, this implies that their meal consists of insects that have simply fallen into the water. From time to time, however, they deliberately attack larger animals, such as fish.
To do this, the creatures can count on a formidable arsenal, with their jaws capable of piercing the skin which they use to inject a lethal venom loaded with powerful neurotoxins, substances devastating to the nervous system of their target.
Once the fish is dead, the spiders drag it onto dry land and administer a veritable chemist's kit to liquefy its bodily tissues, thus making the flesh easier to consume.
Within the animal kingdom, a predator is on average 42 times larger than its prey. Conversely, fish-eating spiders may be smaller than their target.
For example, according to the authors' speculations, a spider of the genus Ancylometesshowing 7 grams on the scale, might be able to catch a 30 gram fish.
Such a disproportionate food source could play an essential role for females during egg production, or for spiders that do not have access to a sufficient insect source.
Either way, one thing is certain: it's more bad news for the little fish.
