蜘蛛也能制作自身模型来转移食肉动物的注意力

中国台湾的科学家近日在台湾东南部海岸的兰屿(Orchid Island)上发现了一种具有奇特本领的蜘蛛，这种蜘蛛名叫二角尘蜘(Cyclosa mulmeinensis)，它能制作自身的模型来转移食肉鸟类等动物的注意力，实现保护自己的目的。

这种蜘蛛是目前发现的第一种能制造出与自身相同大小“复制品”的动物。台湾东海大学的两名生物学家把这一发现刊登在最近一期的《动物行为》(Animal Behaviour)杂志上。

科学家早就发现，蜘蛛喜欢用碎屑、植物机体和捕食后的动物残余等来装饰自己的网，由于这些装饰物的颜色与蜘蛛的颜色相似，因此可以达到伪装自己的目的。研究人员发现，会装饰网的蜘蛛伪装得好，它们受攻击的机率也要小很多。而此次发现的利用自身部位进行伪装的二角尘蜘可谓是蜘蛛界的伪装大师了，它能将采集来的装饰物制作成和自身大小一样的“模型”附在网上，有的二角尘蜘甚至将这些“模型”成串排放增加辨认的难度。

推荐原始出处：

Animal Behaviour doi:10.1016/j.anbehav.2009.05.017

A risky defence by a spider using conspicuous decoys resembling itself in appearance

Ling Tsenga and I-Min Tsoa, b,

aDepartment of Life Science, Tunghai University, Taiwan
bCenter for Tropical Ecology and Biodiversity, Tunghai University, Taiwan

One Darwinian puzzle is that many prey are morphologically or behaviourally conspicuous. Being conspicuous seems detrimental to prey with limited antipredator ability, because conspicuousness is likely to increase detection by predators. Theory predicts that if conspicuousness effectively redirects predator attacks and decreases hunting success, the benefits of enhanced survival can outweigh the cost of conspicuousness. We investigated a conspicuous antipredator behaviour in the orb spider, Cyclosa mulmeinensis, which adds decorations composed of prey pellets and eggsacs to its web. We calculated colour contrasts of spiders against prey pellets and eggsacs and recorded predators' responses to spiders on webs in the field. Webs with more decorations suffered increased numbers of wasp attacks. However because these decorations resembled spiders in size and colour, they functioned as decoys to distract predators and became the focus of predator attacks. By quantifying the costs and benefits of Cyclosa spiders' web-decorating behaviour in a natural setting, we found that this conspicuous antipredator display would enhance overall survival and was adaptive for this vulnerable prey.