蛛网的进化

蛛网的进化是令人感兴趣的一个难题。近年来对这一领域的研究取得许多新进展,修正了以往一些旧的错误观点,蜘蛛的演化已公认为腹部仍保留背板的中纺蛛最先出现,后来产生后纺蛛中的原蛛和新蛛,蛛网起源于原始的穴居蜘蛛在洞穴内壁用丝编织的衬里(丝管),以后丝管出口处向外延伸出领或放射的绊丝,进而出现漏斗蛛科的带丝管(隐蔽所)的片网或皿蛛科网片上下有缠结丝的皿网,圆网在进化到新蛛阶段才出现、起源于有筛器的新蛛,新蛛中一部分种类后来失去筛器,进化为无筛器蛛。园蛛总科中某些科的种类后来又失去圆网,圆网可能来自某些架在空中的片网,而圆网又可以再演变成其他网,如演化为更复杂精致的网,也可以简化而为只有几根丝的三角形网((虫无)蛛科的扇(虫无)蛛)或只有一根丝,靠丝末端的粘滴捕食(园蛛科的流星蛛),效率更高,文中对各主要网型的系统发生作了简明的介绍。当然,网的进化中有一些环节尚不清楚,有待今后进一步研究。

On the Evolution of the Spider Web

This paper gives a brief introduction of current knowledge of the evolution of spider web. The material quoted here is mainly from paper by Shear (1994). The author hopes that the information given in the Chinese text will be useful for the study of the evolution of spider's web and of the behavior of spiders in China.The Mesothelae are generally believed to have evolved first from the common ancestor of all spiders, followed by the Mygalomorphae and the Aranemorphae. Early stages of web evolution are thought to be represented by silk-lined burrows. Next a silk collor is constructed as an extension of the lining, followed by the sheet webs developed by such spiders as agelenids, which incorporates a retreat for the spider. The monophyletic hypothesis of orb-web origin holds that the orb web was invented by an araneomorph that had a cribellum. The araneoids lost the cribeEum, and some araneoid families later lost the orb. It is possible that some aerial sheet webs preceded the orb web, whereas others developed fromthe orb. The orb itself is also ancestral to various ingenious modified webs, some of them more complex and others elegant for their simplicity and efficiency.