The trap-jaw spider is so named for Its ability to sneak up on its prey from behind and snapping its mandibles shut in the blink of an eye, before the victim knows it has been attacked they are already being digested by the trap-jaw.

Trap-Jaw Spiders And Their Speedy, Speedy Jaws

The naked eye won’t help with the trap-jaw spider

Hannah Wood was a graduate student at the University of California, Berkeley, but her study of trap-jaw spiders took her to Chili in the course of her work. While many have an almost irrational fear of spiders, this fear doesn’t generally extend to the trap-door spider as they are, quite simply, tiny and quite difficult to see. Never mind their record-holding jaws.

In her studies, and work in the forest, Wood collected 14 different species of trap-jaw spiders, and returned with them to her lab in Berkeley. It was here that she affixed an eyelash to the head of a pin to watch the trap-jaw spiders “hunt.” With the help of a high-speed video camera capable of recording at up to 40,000 frames per second, Wood found something truly spectacular.

The trap-jaws, which are native to South America as well as New Zealand, use a rubber-band like movement in the jaw to move at ridiculous speeds.

“When you’re a really small organism it’s hard to have quick, strong movements,” said Wood who now works at the Smithsonian Institution’s National Museum of Natural History

“You can easily see the blink of an eye when you record at 1,000 frames per second. To capture the trap-jaw movement, we had to go as high as 40,000 frames per second. It was amazing,” says Wood, whose study was published April 7 in the journal Current Biology. 

Nothing less than super fast

With her video equipment in place, Wood found that the spider’s jaws moved from open to close in 0.00012 second, reaching a speed of roughly 20 miles per hour, or about the same speed that Usian Bolt reaches running the 100 meters.

“There’s so little we know about spiders that someone can go into the field and observe these bizarre behaviors for the first time,” Wood said.

The thing is, these spiders jaws lack any real muscle, and make up for it with speed. Actually, in this case it’s a movement called “power amplification.”

A muscle, even a speedy one, can only move so fast, but through power amplification the spider’s jaws move very similar to that of a rubber band.

So, just like a rubber band, the jaws can open ever so slowly as the spider sneaks up on its prey, then snaps shut at a speed similar to letting go of one end of a stretched rubber band. No matter how fast you try to stretch out a rubber band, when released the end result is the winner of that race. The release will always be faster due to power amplification.

Of all the spiders that Woods and her colleagues filmed the fastest by a bunch was the Zearchaea sp4, a species from New Zealand. While small in size, its speed certainly makes up for it.

What the researchers found from micro-CT scans was that the trap-jaw spiders have elongated jaws with muscles oriented horizontally. While the researchers know this means something they haven’t quite figured out the “how.”

Thankfully, at your size you needn’t worry too much about falling prey to these unique spiders.