Research Shows Ogre-Faced Spider Uses Not Only Sight, But Hearing For Hunting
ARI SHAPIRO, HOST:
All right. As we get closer to Halloween, spiderwebs have been blanketing neighborhoods all over - fake webs, at least. But not all spiders hunt with those round silk traps.
MARY LOUISE KELLY, HOST:
No. Consider the ogre-faced spider - Latin name, Deinopis spinosa. It lives in the southeastern U.S. and launches explosive attacks on its prey using a stretchy net of silk held between its legs. And the spider certainly lives up to its name.
JAY STAFSTROM: The ogre face name itself comes from their massive, hypersensitive pair of eyes.
SHAPIRO: That's Jay Stafstrom of Cornell University. He says those eyes give the spider excellent night vision, which makes sense because the spider hunts at night. Stafstrom's colleague Ron Hoy says the spiders lead an almost Jekyll and Hyde lifestyle.
RON HOY: So by day, this spider essentially plays dead. And then once it gets dark, it changes its personality. It becomes a killer. It becomes a hunter.
KELLY: But in earlier experiments, the scientists began to suspect the spiders don't rely on night vision alone. They had temporarily blindfolded the spiders, yes, and yet the spiders could still snatch prey out of the air, suggesting they relied on another sense.
STAFSTROM: We were curious to know if that might happen to be hearing.
SHAPIRO: So they did a new experiment where the researchers gave the spiders a hearing test. They played sequences of tones kind of like this.
(SOUNDBITE OF TONES)
KELLY: Well, what they found was that certain low-pitched tones would send the spiders catapulting into a back flip, just like they do to catch flying bugs. But of course, there were no flying bugs. Instead, the spiders were fooled by their sense of hearing.
STAFSTROM: We've established that they're using lower frequencies to catch things out of the air.
KELLY: As it happens, those low-frequency tones are in the same frequency range as the wing beats of the spiders' prey, like mosquitoes and moths.
SHAPIRO: The scientists also planted electrodes in the spiders' brains and found they could hear anything from a low rumble to the high-pitched frequencies that you might hear in a pop song. They believe that the spiders detect sounds with tiny stress sensors and hairs on their legs. The work appears today in the journal Current Biology.
KELLY: Hoy says he hopes this work will help people maybe change their views on spiders.
HOY: You know, every Halloween, you drag out spiders, your bats and werewolves. But spiders are fascinating animals. Without them, insects would take over, probably.
KELLY: The idea of insects taking over the world - well, that might be something new to fuel your Halloween fright.
(SOUNDBITE OF RATATAT'S "CREAM ON CHROME") Transcript provided by NPR, Copyright NPR.