Expiscor (20 May 2013)

This week’s Expiscor is coming to you on a holiday Monday across much of Canada. This is the day that many Canadians feel that the ‘warm season‘ has officially arrived. We can plant things in our garden without fear of frost; the lawn shall be mowed, the birds are busy, the butterflies are flying.

What is Expiscor? …it’s a weekly digest of discoveries from the world of entomology, biology, and so much more.

  • It seems that every week there’s a story about ‘dangerous spiders‘ – this week, Bug Girl wrote a post to help FIX THE INTERNET – in this case, to discuss a bogus spider poster.
  • On the topic of jumping spiders – they can make you look twice – WOW, WOW and WOW again. (thanks Alex Wild, for that photo, and permission to use it)

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  • Biodiversity under foot – great video about threats to soil biodiversity (thanks to my former MSc student, and recent PhD graduate, Zach for posting that link.
  • Fireflies: I always find the larvae of the Lampyridae beetles to be odd-looking, and I sometimes have trouble reconciling their habitus with adults.  This is a lot easer thanks to Derek Hennen for this lovely photo of an adult – check out that abdomen! (and thanks, Derek, for allowing me to use this photo)

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  • Scale it. This is VERY worth checking out. I personally like 10 to the power of -2.5
  • A worthy ordeal: Another great post from one of my heroes, Simon Leather – a terrific tradition in the British University system.
  • Lego geek-fest. Star Wars, LOTR, Arrested Development & so much more.
  • To finish, as usual, with some music. I’ve been a fan of Steve Earle for quite a long time, and his latest album (the Low Highway) does not disappoint. Here’s a video from one of the songs from that album. Worth a listen (and a good lesson in there, too)

Do spiders like to dance? Do spiders like music?

A couple of comments on one of my previous posts  piqued my curiosity about Arachnids and sound – one comment talked about how Harvestmen seemed to enjoy the reader’s singing, and another comment suggested a yellow sac spider moved and grooved (danced?) when a record player was playing tunes.


So… it is well known that spiders respond to direct vibrations (i.e., through their webs), but what about sound waves that could be produced by singing or other forms of music?  Do spiders like music? Do they like to dance?

A spider that likes music? Araneus cavaticus (photograph (c) by Tom Murray, published here with permission)

Being a good scientist, I looked to the literature.  Behold, I found a paper published in 1966 in the journal Ecology, titled “Reactions of Orb-Weaving Spiders (Argiopidae) to Airborne Sounds” by Frings and Frings. In this paper, the authors used two common orb-web spiders, and asked whether spiders responded to airborne vibrations as well as to vibrations through their webs.  Unlike previous papers at the time, these authors separated the two possible modes of vibration (i.e., direct vibrations versus airborne sounds).   The Introduction of this paper is wonderful, and provides a series of anecdotes about spiders and sound, including a 1928 citation about how the sensory hairs of spiders moved to the sounds of a mandolin played 5 m away.  As a mandolin player, I was very excited to read this – and I will keep an eye out for spiders when playing!

Frings and Frings collected spiders (including the common orb-web species Araneus cavaticus, of “Charlotte’s Web” fame – it is Charlotte A. Cavatica don’t you know!), used a fancy laboratory set-up to make sounds (and vibrations), and measured responses by their study species.  For one species, the responses were the following ‘1) spasmodic extension of the front legs; (2) jerking of all the legs; (3) shaking the web vigorously by flexing and extending the legs’.

Results:  indeed, their study species respond to airborne sounds, and their responses occur between 200 and 3000 cycles per second (Hertz) and between 90 and 110 decibels.

Let’s put that in perspective –

For Hertz (i.e. cycles per second, or pitch):

Strings on a mandolin range from about 196 Hz to 660 Hz; A barking dog has a range between about 400 Hz and 1000 Hz; The range of a typical human voice is between 80 Hz and 1100 Hz.

For Decibels (i.e., “loudness”)

A violin is between 82 and 92 dB; Singing can be up to 100 dB; A really loud rock concert can be up to 150 dB

 So, if you sing loudly to a spider, play the mandolin for it, or take it to a rock concert, the sound waves produced can elicit responses in spiders.

(A  barking dog will also work.  Or, a dog playing a mandolin)

Might spiders like my mandolin playing more than my family?

Caveats:  the results I mention are for two species only, and it would be  interesting to see whether other species responds in a similar fashion.  Also, I am personally very curious about how spiders respond to different styles of music – classical, bluegrass, punk rock?  THIS is a great research question!

Reference:  Fings, H, & Fings, M (1966). Reactions of Orb-Weaving Spiders (Argiopidae) to Airborne Sounds Ecology, 47 (4), 578-588 DOI: 10.2307/1933935

 Thanks to Tom Murray for permission to use his photograph – more of his work can be viewed here