One of Australia’s tiny spiders, the somersaulting spider is a mystery that takes twice the size of an ant.
Ants—armed with powerful jaws and sometimes chemical weapons—are so dangerous to spiders that less than 1 percent of phalanges attempt to hunt insects (SN: 9/8/21). High-speed footage now reveals Australia’s ant-killer spider (Euryopis umbilicata) can capture this dangerous prey by leaping and draping its victims with silk.
The hunting process is not found in other spider species, researchers report on September 19 Journal of the Academy of Sciences.
“This behavior is just fascinating. I’ve never seen this type of hunting myself,” says Paula Cushing, an evolutionary biologist and curator of invertebrate zoology at the Denver Museum of Nature & Science, who was not involved in the study.
Alfonso Aceves-Aparicio, a human ecologist at the Max Planck Institute for Chemical Ecology in Jena, Germany, stumbled across somersault spiders while walking home one night. A graduate student at Macquarie University in Sydney at the time, Aceves-Aparicio was intrigued when he noticed dark dots shooting through the pale bark of a eucalyptus tree.
Small spider webs moving between ants. Suddenly one of the spiders jumped out. “I thought the ant had escaped,” Aceves-Aparicio recalls. “But then I saw a floating ant and I thought, woah, something’s going on here.”
Aceves-Aparicio borrowed a high-speed camera to get a closer look at what the spiders were doing. While slowing down the action, he and his colleagues could see that the spider was actually hunting a completely unknown ant.
Most spider ants use hunting webs or sneak up on their prey from behind to minimize the risk. However, although their prey was smaller, the Aceves-Aparicius spiders gathered sugar ants.Cousin Camponotus) head laid Each spider had positioned itself so that it could watch the ants on the tree. Approaching one, the spider overcame the prey. Once upon a time in the air a spider’s thread of silk lay upon an ant.
This one connection made – in the space of a thousandth of a second – decided whether the hunt would succeed. If the nerves are stuck, then the spider flies around the ants, surrounds them more delicately with silk, and leaving the legs, it can be snatched away and consumed.
What stood out to Aceves-Aparicio and colleagues was the effectiveness of the technique. Predators like lions and wolves tend to miss about 50 percent of their intended targets. The success rate of the 60 spider hunts that the researchers filmed was 85 percent.
For Aceves-Aparicio, the discovery shows that individual behaviors can be hidden in plain sight. “The news here is a bit of curiosity and attention,” he said. “There are things going on everywhere. We just have to find them there.”
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