Some spiders wait for prey to come and tickle their web. But the ogre-faced spider (Deinopis spinosa) uses its sense of hearing to take its web to the prey.
Hanging upside down, the spider weaves a rectangular web between its legs. When an insect flies behind the dangling arachnid, the spider swings backward, casting the web toward the prey. This behind-the-back hunting technique is one clue that the spiders can hear an unexpectedly wide range of sounds, researchers report online October 29 in Current Biology.
“A couple years ago, we didn’t really have a great idea that spiders could hear,” says Jay Stafstrom, a sensory ecologist at Cornell University. But now, he and his colleagues have looked at several spider species, and most can hear using specialized organs on their legs, he says. That includes jumping spiders, which respond to low frequencies (SN: 10/15/16). Surprisingly, ogre-faced spiders can also hear fairly high frequencies, Stafstrom says.
Stafstrom and colleagues inserted microelectrodes into the brains of 13 ogre-faced spiders, and then played tones of varying frequencies from a speaker while monitoring the spiders’ auditory nerve cell activity. Spikes of activity revealed that the spiders can sense airborne sounds between 100 and 10,000 hertz, though not at every frequency, the team found. (Humans generally hear between 20 Hz and 20,000 Hz.)