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Spider that makes life-sized decoys of itself to escape predators identified.

Byline: ANI

London, July 7 (ANI): Scientists have identified a species of spider that builds models of itself that it uses as decoys to distract predators, which may be the first example of an animal building a life-size replica of its own body.

Many animals try to divert the attentions of predators by becoming masters of disguise.

Some try to avoid being seen altogether by using camouflage to blend in against a background, such as the peppered moth evolving motley wings that blend into tree bark, or stick insects that look like sticks.

Others evolve more conspicuous ornaments designed to distract a predator, such as butterflies that grow large eyespots or lizards that quickly move colourful tails, which they detach from their bodies if grabbed.

But, animals do not tend to actually build life-like replica models of themselves to act as decoys.

According to a report by BBC News, that is exactly what a species of orb spider called Cyclosa mulmeinensis does, biologists Ling Tseng and I-Min Tso of Tunghai University in Taichung, Taiwan, have discovered.

This and other related spiders in the same genus decorate their webs with material such as detritus, plant parts, prey remains or egg sacs.

Because such detritus is often of a similar colour to the spider, researchers suspected it might help camouflage the arachnid.

Cyclosa mulmeinensis, which lives on Orchid Island off the southeast coast of Taiwan, decorates its web with both the remains of dead insect prey and egg sacs.

Intriguingly, the spiders make prey pellets and egg sacs that were the same size as its own body.

The researchers also found that these decorations appeared to wasps to be the same colour, and reflect light in the same way, as the spider's body.

In short, the spider made decorations that were of the same size, shape and appearance as itself.

"Our results show that this vulnerable spider protects itself from predator attacks by constructing decoys that increase the conspicuousness of the web, and resemble its own appearance in size and colour," according to the researchers.

"When both spiders and web decorations are present on the same web, they look like a string of nearly identical oval objects to the predators," said Tso.

"I don't know of any animal that actively builds a decoy of itself. Our study seems to be the first to empirically demonstrate the function of animal-made decoys," he added. (ANI)

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Publication:Asian News International
Date:Jul 7, 2009
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