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Photo: Gabriel Rojo / Nature Picture Library / IMAGO
Spiders have long fascinated humans with their way of hunting: their elaborate webs, which they flash across as their prey becomes entangled.
For a study published in the journal Proceedings of the National Academy of Science, researchers have now observed a particularly striking form of hunting by a species of spider.
Arachnids are the most species-rich taxon of carnivores, the authors write, and they have an amazing range of strategies to hunt theirs.
Some groups of spiders, such as the Australian Theridiidae, also pursue unexpected prey: ants.
And this despite the fact that the insects could injure or kill spiders.
According to the researchers, only 0.3 percent of known spider species feed on ants.
The Theridiidae have developed their own strategies to outsmart their overpowering opponents.
The authors write: "The hunting sequence consists of ritualized steps that are performed in fractions of a second, resulting in an exceptionally high success rate in prey capture."
According to the study, Theridiidae, Latin name Euryopis umbilicata, hide under the bark of eucalyptus trees during the day and only venture out at dusk.
They don't spin a web to hunt, but simply wait for their prey.
As soon as the ant approaches, the spider performs an acrobatic strike on the insect, immobilizing the animal.
The spiders then attach their opponents to the tree bark with a thread made of sticky, viscous silk, the study says.
Most of the spiders hunted focused on a specific species of ant as prey -- which is very unusual, the study says.
Predators would typically feed on a variety of prey.
In addition, the size ratio is unusual: Normally, predators would feed on smaller animals.
However, the study found ants that were about twice as long as the spiders but had a similar mass.
For the study, the researchers carried out field observations and experiments in order to be able to understand how the arachnids hunt.
"We used high-speed videography and scanning electron microscopy to characterize the spiders' attack and use of silk during staged attack sequences in their natural habitat," the scientists write.
The targeted feeding of prey was also part of the investigations.
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