Telegraph 24 Aprile 2009

L’uomo discende dal ragno? Come lo spiegheranno gli evoluzionisti?

Scientists have found themselves raising a smile when studying this creature - the happy face spider.

The spider, which measures just a few millimetres across, has developed bizarre markings giving the appearance of a smiling face.

Scientists think the spider, which has the scientific name Theridion grallator and is harmless to humans, has evolved the patterns to confuse predators.

It is under-threat of extinction in the rainforests of the Hawaiian island chain in the Pacific.

Dr Geoff Oxford, a spider expert from the University of York, said: "I must admit when I turned over the first leaf and saw one it certainly brought a smile to my face.

"There are various theories as to why the spider has developed the markings it has, one of these that it may be to confuse predators.

"When a bird or other predator first sees a prey item it has not seen before there is a moment before it decides whether to eat it or not.

"It may be that this spider has developed these variations to take advantage of this, in the moment the predator is deciding if it is food it may have the chance to escape.

"I don't think the smiling face is enough to put off a bird though, but it would be nice to think so. Not all happy-face spiders have such striking markings, and some are nearly all orange or all blue.

"The species is only found high in the rainforests of Hawaii and are under threat from the introduction of animals not native to the islands."

Dr Oxford, who has been studying the spiders since 1993, said that the unusual markings of the arachnid had made them a symbol of all of Hawaii's threatened wildlife.

"They are ambassadors for all the threatened invertebrates, insects and spiders on Hawaii," he said.

"Conservationists are using them to highlight the plight of native species and you can't go far on the islands without seeing them on T-shirts, baseball caps, post cards and even removal trucks.

"The Hawaiian fauna is being threatened by all the human-imported species of animals and plants that establish there each year.

"Sadly most of the plants and animals in lowland areas of Hawaii are non-native and one has to go up into the rainforest to find the native species."

Source >  Telegraph | Apr 22