Trap-Jaw Spider Attack Seen in High-Speed Video

Posted on April 8, 2016

Mecysmauchenius trap-jaw spider female

Hannah Wood of the Smithsonian Institution's National Museum of Natural History has been fascinated by spiders ever since she was a child. She has been studying Mecysmaucheniidae spiders (trap-jaw spiders) ever since she first encountered one in Chile. The spiders live only in New Zealand and southern South America.

Researchers have discovered that the high-speed, power-amplified strike of the trap-jaw spider has evolved at least four different times within the Mecysmaucheniid family of spiders. The photograph above shows a female trap-jaw spider. Wood began recording the spiders after she noticed they would sit with their jaw-like chelicerae open and ready to snap. She kept as many as 100 of the spiders in her apartment at any given time. She recorded them using high-speed cameras to observe their jaws rapidly closing.

Her high-speed video recordings showed that when an insect comes close, the spiders snap their chelicerae shut with incredible power and speed. The videos revealed a great range of cheliceral closing speeds among the 14 species of Mecysmaucheniid spiders. The fastest species snaps its chelicerae more than two orders of magnitude faster than the slowest species.

The power output from four of the spider species exceeded the known power output of muscles. The researchers have not yet determined how the spiders are storing this unaccounted for energy.

Wood says in a statement, "Studying these spiders could allow humans to design robots that move in novel ways that are based on how these spiders move."

Here is a video showing a trap-jaw spider (Semysmauchenius) in action. The video was recorded at 3,000 frames per second (fps), but is playing at 20 fps. In real life the movements would be 150 times as fast. Take a look:

The research paper on the trap-jaw spiders can be found here in the journal, Current Biology.

Photo: H. Wood

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