Mecysmaucheniid spiders — which occur only in New Zealand and southern South America — have a remarkable ability to strike their prey at very fast speed and with super-spider power, says a team of scientists led by Dr. Hannah Wood from the Smithsonian Institution’s National Museum of Natural History.
Spider Mecysmauchenius sp. uses power-amplified high-speed predatory strikes. Image credit: H. Wood.
Mecysmaucheniidae is a relatively small family of spiders with 25 described species in seven genera.
Because these spiders are minute creatures that hunt for prey on the ground, they are hard to spot, even with trained eyes.
But according to Dr. Wood and co-authors, Mecysmaucheniid spiders are more remarkable than they look.
“The high-speed predatory attacks of these spiders were previously unknown,” said Dr. Wood, who is lead author on a study published in the journal Current Biology this week.
“Many of the species I have been working with are also unknown to scientific community.”
As the report shows, high-speed videos of 14 species of Mecysmaucheniid spiders revealed a great range of mouth-part closing speeds.
The fastest Mecysmaucheniid species snaps its chelicerae (the mouthparts of spiders) more than two orders of magnitude faster than the slowest species.
The power output from four of the species exceeded the known power output of muscles, the team found.
“In other words, the spiders’ movements can’t be directly powered by the spiders’ tiny muscles, particularly given the short times and small distances covered during a strike,” the scientists said.
“That means other structural mechanisms must allow the spiders to store energy to produce their ballistic movements.”
Using DNA analysis, the team found that the high-speed, power-amplified strikes have independently evolved at least four different times – phenomena known as convergent evolution — within the family Mecysmaucheniidae.
In addition to providing new insights into spiders and their evolution, the new findings may also have broader implications.
“Studying these spiders could allow humans to design robots that move in novel ways that are based on how these spiders move,” Dr. Wood said.
_____
Hannah M. Wood et al. Repeated Evolution of Power-Amplified Predatory Strikes in Trap-Jaw Spiders. Current Biology, published online April 7, 2016; doi: 10.1016/j.cub.2016.02.029
