The ogre-faced spiders (Deinopis Spinosa) in the dark can catch insects flying away from the eyesight with perfection. Various researchers wonder how does this happen? Scientists from Cornell have settled the confusion.
In a recent study, published in Current Biology, on Oct. 29 researchers have confirmed that ogre-faced spiders use metatarsal sensitivity – sensors at the tip of the leg – to determine the initial playback at multiple frequencies up to 6 feet away. The sound made by airborne insects is well known to the spider and likewise, it reacts to those only with a backflip to hunt the airborne insects.
Lead author Jay Stafstrom says “These spiders have finely tuned sensory systems and a fascinating hunting strategy.”
Adding to it he also said, “It’s unique, These spiders have massive eyes so they can see at night and catch things off the ground, but they can ‘hear’ quite well, detecting sound through their metatarsal organ, as these spiders excel at catching things from the air.”
These nightly spiders are mostly found in the south-eastern united states. Spiders generally make orb webs but the ogre-faced spiders make their small nets.
Hoy said, “For these spiders, they’re doing a Willie Mays thing.” He also said, “ So here comes a flying bug and somehow the spider gets information on the sound direction and its distance. The spiders time the 200-millisecond leap if the fly is within its capture zone – much like an over-the-shoulder catch. The spider gets its prey. They’re accurate.”
The spiders don’t have ears but they can detect a wide range of sound due to the metatarsal organ present near the tip of their legs. Stafstrom said, “Their acoustic sensitivity is sufficient to trigger that backward strike behavior.”
These spiders were collected by Stafstrom and he brought them to Hoy’s lab. Gil Menda analyzed the neural activity from the brain and legs of the spider. He played different tones and observed that the spider’s neurons responded to various tones.
Stafstrom said, “While the spiders were sensitive to low-frequency tones, as expected, we didn’t expect to see net-casting spiders sensitive to a wide range of frequencies – all the way to 10 kilohertz.”
Charles Walcott’s theory about “spider’s metatarsal organ was sensitive to different frequencies of sound” has now been proved by Stafstrom’s outcome. Previously European researchers have made fun of Charles’s theory.
Walcott’s theory has been proved right by Stafstrom and Hoy’s effort after 60 long years. Walcott said, “Spiders are sensitive to airborne sound, That’s the big message.”
Source – cornell