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Attack behavior of diguetid spiders and the origin of prey wrapping in spiders

1967; Cambridge Entomological Club; Volume: 74; Issue: 2 Linguagem: Inglês

10.1155/1967/867474

1687-7438

William G. Eberhard,

Fossil Insects in Amber

Spiders use silk in prey capture in two ways: in the construction of webs which trap and partially immobilize prey, and in wrapping prey.Aerial webs have evolved independently in several families of spiders, including the Araneidae, Uloboridae, and Diguetidae (Kas- ton, 1966).As pointed out by Savory (1952, p. 20), a spider's web greatly extends the area covered by its sense of touch ; it also at least partially immobilizes any prey which encounters it.Thus a web- living spider is more likely to "encounter" a new, partially subdued prey while handling another than is a webless spider.Most prey which become caught in a web will eventually work free and escape unless they are further immobilized.Barrows (1915) found that flies remained in the orbs of Araneus sericatus (Epeira sclopetaria) an average of only 5 seconds.However, most aerial web spinning spiders hang upside down in their webs, and if they dropped a prey which they had already caught while making a new attack, it would fall from the web and be lost.It is probably for this reason that many of these spiders wrap their prey and secure it to the web soon after encountering it, thus freeing their chelicerae for subsequent attacks.Araneids and uloborids spin orb webs and use silk extensively to immobilize prey.Diguetids spin less highly organized webs, and never use silk in prey immobilization.However, they often apply silk to prey already subdued by biting.This paper shows how post- immobilization prey wrapping may have led to the use of silk as an attack weapon by the orb weavers.I observed the following species attacking prey: Aphonopelma sp.(Theraphosidae, various ages, both sexes), Metepeira labyrintha (Hentz) (Araneidae, various ages, both sexes), Argiope trifasciata (Forskal) (Araneidae, females of various ages), Uloborus diverms