These spiders listen for prey before slinging their webs like catapults

A spider came along

The 19 spiders built 26 webs during the test period. For the experiments, Han and Blackledge used a weighted tuning fork with mid-range frequencies for buzzing wings for many mosquito species in North America as a control stimulus. They also attached real mosquitoes to thin strips of black construction paper by dabbing a dab of superglue on their bellies or hind legs. This ensured that the mosquitoes could still flap their wings as they approached the web. The experiments were recorded on high-speed video for analysis.

As expected, spiders released their webs as fluttering mosquitoes approached, but the video footage showed that the release occurred before the mosquitoes ever touched the web. The spiders released their webs as often as the tuning fork was waved nearby. They were not likely to rely on visual cues because the spiders were in the center of the web and anchor line, and facing away from the cone. Ray spiders also do not have well-developed eyes. And one spider did not respond to a motionless mosquito held in the capture cone, only releasing its web when the insect began to flap its wings.

“The decision to release a web is therefore likely based on vibration information,” the authors concluded, noting that ray spiders have sound-sensitive hairs on their hind legs that could detect air currents or sound waves, as those legs are typically closest to the cone. Static webs are known to vibrate in response to airborne sounds, so it seems likely that skate spiders can figure out an insect's approach, size, and perhaps even behavior before its prey ever makes contact with the web.

As for web kinematics, Han and Blackledge found that they can accelerate up to 504 m/s²reaching speeds of up to 1 m/s, allowing it to catch mosquitoes in 38 milliseconds or less. Even the fastest mosquitoes can have trouble avoiding that.

Journal of Experimental Biology, 2024. DOI: 10.1242/jeb.249237 (About DOIs).