National Geographic

The threatening vibes of whip spiders (Warning: NSFA)

If any group of animals looks like a nightmare made real, it’s the whip spiders. Also known as whip scorpions, these creatures look like flattened versions of true spiders, and they’re close relatives of their namesakes. Their front pair of legs has been transformed into long ‘whips’, which they flail ahead of their bodies to search of prey. Anything unfortunate enough to make contact gets grabbed by the whip spider’s massive pincers, each twice as long as the animal itself and tipped in fiendish spikes.

Despite these fearsome weapons, fights between whip spiders are more sedate affairs. They’re more like dances, carried out to strict protocol and consisting largely of bad vibes. Two whip spiders circle one another and start gently probing each other with their whips. These movements become increasingly jerky and intense until the spiders start rapidly vibrating their whips in front of their opponents, without touching them. At this point, one fighter usually retreats. Naive individuals only ever come to blows in 27 percent of contests and experienced ones only attack on 9 percent of them.

Roger Santer and Eileen Hebets have found that the vibrating whips are the key to a speedy resolution. The whip spider Phrynus marginemaculatus detects these vibrations with exquisitely sensitive hairs known as trichobothria, found along their legs. A few years ago, the duo recorded electrical signals from the hairs, and found that they respond to vibrations of the same frequency as those made by the whips. Now, they’ve found that when they shaved the hairs from rival whip spiders, the threat displays went on for around twice as long and were three to four times more likely to escalate into physical fights.

Santer and Hebets think that the vibrations allow the combatants to advertise their size and strength. This gives them enough information to save energy and avoid injury, by calling off a fight if they know they’re going to lose. Similar hairs are found throughout the arthropods – the group that includes insects, spiders, scorpions, crustaceans, and so on. Santer and Hebets suggest that the whip spider’s vibration-based messages could be a common style of communication within this varied group.

Reference: Santer & Hebets. 2011. Evidence for Air Movement Signals in the Agonistic Behaviour of a Nocturnal Arachnid (Order Amblypygi). PLoS ONE http://dx.doi.org/10.1371/journal.pone.0022473

Image: (source)

There are 14 Comments. Add Yours.

  1. sheila
    August 15, 2011

    I went searching on YouTube for a video of two males vibrating at each other. Mostly found videos of pet whip spiders. Any links for me?

  2. mo
    August 15, 2011

    whip scorpions are not the same as whip spiders.

    http://en.wikipedia.org/wiki/Whip_scorpion

  3. Ed Yong
    August 15, 2011

    I checked that but I saw places where both terms were used interchangeably to describe the group I’m writing about.

  4. Arun
    August 15, 2011

    What does NSFA mean?

  5. GreenO
    August 15, 2011

    Not Safe For Arachnophobics, presumably.

  6. Ed Yong
    August 15, 2011

    Ding ding ding!

  7. arensb
    August 15, 2011

    If any group of animals looks like a nightmare made real, it’s the whip spiders.

    Didn’t we see those as spaceships in the third and fourth seasons of Babylon 5?

  8. Sheila
    August 15, 2011

    Haha, I don’t think the NSFA warning works for my subscription to the feed in google reader, I still see the photo. It’s not a problem for me, but it might freak out people who need the warning.

  9. P.N. Elrod
    August 15, 2011

    My mind if still wrapping around the fact that someone is getting paid to shave spiders.

  10. G.S.
    August 15, 2011

    We have these “wind scorpions” (a more poetic name, putting in mind an aeloian harp) in the storage room of our house down near Belize. They’re as big as my hand, and they’re pretty fearless, walking out to look at me whenever I go inside to find something.

    And when they come out, they often make a kind of scratchy sound, as if they’re dragging a limb or two across the rock. Could that possibly be the sound they make with their whips?

    I’m perfectly happy to see these giant orange scorpion/spider things, since they’re perfectly harmless. They’re also only ever in one place, so I know where to find them.

    G.S.

  11. Azkyroth
    August 16, 2011

    Awww. :3

  12. Zach Miller
    August 16, 2011

    I’ve always seen the Amblypygi referred to as “whip scorpions” since they have pincers.

    @G.S. I don’t think any amblypygids get to be as large as your HAND, unless you just mean the width of their legs. Either way…yeep! I don’t know how much I like an arachnid that just kind of comes out to let you know it’s aware of you.

    At least they’re not solfugids, which can actually be aggressive (from all I’ve read).

  13. V
    August 18, 2011

    “wind scorpion”often refers to Solifugae, “whip scorpion” to Uropygi, and “whip spider” to Amblypygi, but common names are fuzzy.
    Solifugids are never “aggressive” although they may bite/pinch if handled, and they may “chase” you in very hot areas to get into your shadow. They aren’t venomous or dangerous, at most the bite is a little pinch.
    Arachnophilia!

  14. Bogleech
    August 31, 2011

    Very fond of Amblipygids, though I’ve never had a chance to own them.

    Inexplicably, an Amblipygid was featured in Harry Potter, recreated accurately in CG except for the ability to squeal and chirp like some sort of little monster. I wonder why they didn’t just invent their own creature if they were making a CG model anyway.

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