Hanna Wood

NZ spider has the fastest jaw in the West

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A New Zealand spider is the fastest in the world at snapping up prey with its jaws, suggests a new study by US scientists. The researchers looked at trap-jaw spiders, which only live in New Zealand and South America, and found that the New Zealand type - called Zearchaea - was so fast they had trouble recording the act with a high-speed camera on its highest setting.

Journal/conference: Current Biology

Organisation/s: Smithsonian Institution, USA

Media Release

From: Cell Press

These trap-jaw spiders strike their prey with lightning speed

Mecysmaucheniidae spiders, which live only in New Zealand and southern South America, don't look like much. They are drab and tiny spiders that hunt for prey on the ground. But researchers reporting in Current Biology on April 7 show that these spiders actually have a remarkable ability to strike their prey with lightning speed.

This high-speed, power-amplified strike has evolved at least four different times within the Mecysmaucheniid family of spiders, the researchers have found.

"This research shows how little we know about spiders and how much there is still to discover," says Hannah Wood of the Smithsonian Institution's National Museum of Natural History. "The high-speed predatory attacks of these spiders were previously unknown. Many of the species I have been working with are also unknown to scientific community."

Unlike many young children, Wood always liked spiders. She also loved to travel to far-flung places around the world to study them. After her first encounter with a trap-jaw spider in Chile, she noticed that they would sit with their jaw-like chelicerae open and ready to snap. She started recording them.

At the time, Wood was a grad student. She says she began keeping about 100 of the spiders in her tiny apartment at any given time. She recorded their activities on a little CCD camera with a large macro lens, and then started using high-speed cameras.

Her high-speed video recordings showed that when a tasty insect comes close, the spiders snap their chelicerae shut with incredible power and speed. That kind of predatory behavior had been seen before in some ants, but it was unknown in arachnids, the group including spiders.

As the new report shows, high-speed videos of 14 species of Mecysmaucheniid spiders revealed a great range of cheliceral closing speeds. 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 found. In other words, they explain, 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.

That means other structural mechanisms must allow the spiders to store energy to produce their ballistic movements. The researchers have already described some anatomical differences in the power-amplified trap-jaw spiders. However, Wood says they aren't quite sure how it works and are now conducting further investigations designed to find out.

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," Wood says.

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Expert Reaction

These comments have been collated by the Science Media Centre to provide a variety of expert perspectives on this issue. Feel free to use these quotes in your stories. Views expressed are the personal opinions of the experts named. They do not represent the views of the SMC or any other organisation unless specifically stated.

Dr Cor Vink, Curator of Natural History , Canterbury Museum

It is a very interesting finding. The late Ray Forster, New Zealand’s most prolific arachnologist, had hinted at the possibility of this prey capture method due to their unusual peg teeth, which are beside the fangs.

I can’t imagine why these spiders would have evolved such an elaborate prey capture mechanism. They don’t seem to have specialised in any particular prey and have been reported to feed on a range of insects and spiders.  

It’s interesting to note that the fastest recorded jaw movements were found in an undescribed species in the genus Zearchaea. It is one of a dozen undescribed Mecysmaucheniidae in New Zealand, which shows that there is so much more to learn about our unique and unusual spider fauna.

There are an estimated 2000 species of spiders in New Zealand, with 95% of them endemic and at least 700 species undescribed.

Last updated: 03 Nov 2016 7:19pm
Dr Greg Holwell, Senior Lecturer, School of Biological Sciences, University of Auckland

This paper shows us the first example of a group of spiders that use a power-amplified predatory strike. Their jaws can strike at prey with more power than would be physically possible using muscle, so some other mechanism must be used.

Excitingly for New Zealanders, a number of species from this amazing family of spiders are found right here in New Zealand, including a species of Zearchaea with the fastest jaws of all"

These are tiny and cryptic spiders, some less than a millimetre long. Although the paper does not discuss what they eat, this lightning strike might allow them to dispatch of their prey efficiently, or possibly tackle larger prey than other spiders their size can manage. I look forward to seeing where this exciting research develops in the future.

Last updated: 03 Nov 2016 5:46pm
Associate Professor Ximena Nelson, School of Biological Sciences, University of Canterbury

I found this a very interesting paper - and in some ways a very surprising paper. Trap-jaw ants and mantis shrimps are known for extremely fast and powerful movements, but you only have to watch (or be bitten or hit by) these animals to see their speed in the relevant motions.

Movement speed and power has never been investigated in spiders before-  certainly with regards to predation.  

Given the size of the spiders involved (only a few millimetres at most) maybe this is why we have not ‘noticed’ this fast behaviour until this elegant study which combined molecular phylogeny, high-speed video of behaviour, and morphological measurements and 3D reconstruction of structures based on very sensitive technology (micro tomography) on a number of species. However, as someone who works with spiders I am also not surprised to hear about something new and unexpected in this understudied yet extremely varied group of animals.

It is intriguing that there is such large variation in the predatory strike speed depending on species in this family. As hunters that search for prey without a web, they are likely to rely heavily on their chelicerae (mouthparts) to subdue prey before venom takes effect. However, why some species have speeds that differ by a factor of a hundred is perplexing, and highlights the need to understand their behaviour- in particular, the type of prey that these spiders hunt. They may even bite in defence against predators, which would again be somewhat unusual for animals that typically drop to the ground, remain motionless, or hide to avoid predation. 

Last updated: 03 Nov 2016 4:40pm

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Multimedia:

  • Trap-jaw spider
    Trap-jaw spider

    Chilarchaea quellon, anterior view, male: looking at the face of a trap-jaw spider, the long chelicerae are in front and you can see the fangs at the tip.

    File size: 6.9 MB

    Attribution: Hannah Wood

    Permission category: © - Only use with this story

    Last modified: 03 Nov 2016 5:00pm

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  • Trap-jaw spider
    Trap-jaw spider

    Mecysmauchenius victoria, lateral view, female: how these spiders look in the field, this species is a slower species and does not have a power-amplified high-speed predatory strike.

    File size: 5.5 MB

    Attribution: Hannah Wood

    Permission category: © - Only use with this story

    Last modified: 03 Nov 2016 5:47pm

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  • Trap-jaw spider
    Trap-jaw spider

    Mecysmauchenius new species, female: how these spiders look in the field, this species uses power-amplified high-speed predatory strikes.

    File size: 5.9 MB

    Attribution: Hannah Wood

    Permission category: © - Only use with this story

    Last modified: 03 Nov 2016 6:17pm

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  • Video: trap-jaw in action

    Video of a spider capturing prey by snapping its jaws.

    File Size: 2.1 MB

    Attribution: Hannah Wood

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    Last Modified: 03 Nov 2016 7:09pm

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  • Video: trap-jaw in action

    Video of a spider capturing prey by snapping its jaws.

    File Size: 6.0 MB

    Attribution: Hannah Wood

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    Last Modified: 03 Nov 2016 4:51pm

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  • Video: trap-jaw in action

    Video of a spider capturing prey by snapping its jaws.

    File Size: 2.0 MB

    Attribution: Hannah Wood

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    Last Modified: 03 Nov 2016 7:12pm

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  • Adult male Zearchaea clypeata
    Adult male Zearchaea clypeata

    A spider from the Zearchaea genus only found in New Zealand.

    File size: 71.9 KB

    Attribution: Public Domain

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    Last modified: 03 Nov 2016 7:01pm

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  • Adult female Zearchaea clypeata
    Adult female Zearchaea clypeata

    A spider from the Zearchaea genus only found in New Zealand.

    File size: 351.0 KB

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    Last modified: 03 Nov 2016 5:11pm

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