High-speed footage of a net-casting spiders hunting technique has been recorded by a film crew. As ambush hunters, the spiders are known to use a combination of touch and well-developed sight to sense prey. The video reveals the rarely-seen, split-second technique of the species as it snatches an unsuspecting cricket in a Central American forest. The team believe this is the first slow-motion footage to show a net-casting spider hunting in the wild. Expert, Dr George McGavin, who witnessed the event said: I would compare it to watching a big cat kill. Its as exciting as that. The film crew were in central America filming wildlife for a new nature series, The Dark: Natures Nighttime World. They waited for five hours with the cameras trained on the spider until the cricket strayed into the killing zone beneath the net. The spider did not move a muscle until the antenna of that prey item, the cricket, touched the thread. As soon as it touched it, [the spider] was on it in a thousandth of a second, said Dr McGavin, if we hadnt had that camera, you wouldnt have seen a thing. It was the most exciting thing Ive ever seen, he said. Net-casting spiders are found across the world in tropical and sub-tropical regions and are also known as ogre-faced spiders because of their distinctive big eyes, which help them to see prey during nighttime hunts. But on this occasion, the team also captured the important moment that triggers the spiders trap. When the cricket touched one of the nets anchoring threads with its antenna, it caused the spider to strike. Its like a trip wire, said Craig Walker, deputy team leader for invertebrates at the Zoological Society of London. Itll send a vibration to the spider. The spiders construct their webs in stages, first building a scaffold at a spot under which its prey is likely to pass. Its almost like manufacturing your own workbench so that you can make something on it, Mr Walker told BBC Nature. The spider then carefully crafts its distinctive net using a different type of silk. They spin some of the silk at its most extended so its already at full stretch when its spun so that when its off the scaffold itll immediately shrink to its non-stretched size, he said. They hit the prey with it at full stretch and then they relax it so that it gets caught into it, almost like a purse net. Sometimes spiders of this genus use an extra technique to help them to pick out their prey at night. (They) will spend a little while spraying faeces on to the ground which dry white and then the dark animal has to run across it and its a bit like putting a flash light on something, said Mr Walker. 29 July 2012
Posted on: Sat, 20 Sep 2014 00:07:00 +0000
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