Trap-Jaw Spider Family Seizes Prey with Lightning Speed – Discovery News

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A family of trap-jaw spiders can snap its jaws down on prey with unprecedented, lightning speed, and with unexpected force, according to a new study on predatory spider strikes.

Under study was the Mecysmaucheniidae family of spiders, tiny (about 1 to 3 millimeters long) and unexceptional arachnids found only in New Zealand and South America that hunt on the ground for their prey. Drab though they may be, though, their bite is anything but unexceptional.

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Hannah Wood, of the Smithsonian Institution’s National Museum of Natural History, led the study, the results of which have just been published in the journal Current Biology.

Wood had observed in prior work that trap-jaw spiders would stalk their prey with their jaws wide open and then, once the prey was close enough, snap them shut fast, with the pitiless ferocity of a mouse trap.

Determined to get a closer look, Wood made a group of high-speed video recordings of 14 species in the Mecysmaucheniidae family. Some species, she noted, snapped their jaws shut so fast only video shot at a staggering 44,000 frames per second could slow it down enough for the action to be closely observed.

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The speed of the jaw-snapping varied among the species, Wood found, with the fastest bite being 100 times faster than the slowest. How fast? Just over a 10th of a millisecond in one species.

“These are the fastest-known arachnids so far,” Wood told

Here’s a video of that speed in action. It shows the species Semysmauchenius, in footage recorded at 3,000 frames per second (fps). But, it’s playing at 20 fps, so in real life the movements would be 150 times as fast:

And, it wasn’t just speed at play in the quick-jawed arachnids. Wood and her colleagues determined that four of the species output more power than their own tiny muscles should have permitted them to.

This told the researchers that other structural mechanisms must allow the spiders to store energy they can expend when they need to make their blindingly fast strikes.

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The biological ability to store energy like that is called power amplification. Wood and her co-authors remark in the study that this type of predatory behavior — the “power-amplified” snap-shut seen in the spiders — has been documented before in some ant species but never before in arachnids.

The researchers say they aren’t sure yet what mechanism accounts for the energy storage that drives the spider’s power-amplified behavior. They’re currently studying the issue.

“This research shows how little we know about spiders and how much there is still to discover,” said Wood in a statement. “The high-speed predatory attacks of these spiders were previously unknown.” 

Trap-Jaw Spider Family Seizes Prey with Lightning Speed – Discovery News