Wednesday, October 3, 2012

Evolution
The Bolas Spider!

There just doesn't seem to be any end to their skills, and the Bolas Spider is one extraordinarily skilled hunter. Bolas spiders are around 66 species of three related genera and are found in America, Africa and Australasia. Here's a typical scenario:
During the day, the female Bolas spider is just hiding in passive disguise looking like a snail or a bird dropping, although she
can often be found in fairly exposed places. The male is much smaller than the female and use a different technique that we'll talk about later. Now, the main prey for these spiders is male moths. But traditional orb webs are not effective for capturing moths, because only their scales will stick on to the webs, allowing the moth to escape. And here's where the interesting part comes in- as you see in the pic, the female spider hangs a small bolus by a vertical thread. This bolas is covered in watery stuff that flows through the scales of the moth so that glue in the middle can stick onto the actual moth underneath. And it doesn't end there. The female spider also secretes pheromones that are irresistible to the male moths, thereby increasing their chances. Moreover, depending on the species of moth, they can even change the scent of the pheromone to attract the specific moth species.
And if this strategy fails, which is almost never the case, the female will eat her own bolus within half an hour or so.

The males and spiderlings hunt without a bola, as their bola are too small and they usually hunt directly for small flies.

Don't miss out this amazing video by David Attenborough himself :
http://www.youtube.com/watch?v=2UfMJJAzvbI

Source:
1) For more amazing pics: http://nathistoc.bio.uci.edu/spiders/Mastophora.htm
2) http://www.dailykos.com/story/2006/06/02/215350/-Science-Spider-Friday-The-Bolas-Spider
3) http://www.realmonstrosities.com/2012/08/bolas-spider.html

Image: Stormcoat, San Diego, CA from- http://bugguide.net/node/view/275936

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