PREDATORY BEHAVIOR OF SPITTING SPIDERS (ARANEAE : SCYTODIDAE) AND THE EVOLUTION OF PREY WRAPPING I

Abstract

The predatory behavior of the spitting spider Scytodes sp. was studied in the laboratory, and an ethogram of the predatory behavior was developed. The principal components usually occur in the order: tapping, spitting, biting, wrapping, feeding. Spitting results in a pair of sticky, zig-zag, transverse bands which pin the prey to the substrate. At the capture site scytodids wrap the prey using the typical form seen in the higher spiders: the spider holds the prey in both third legs and alternates the use of right and left fourth legs in applying silk. Prey are eaten at the capture site. A comparison of prey wrapping by spiders in primitive aerial-web building species with that used by typically vagrant species which forage on elevated substrates shows two very different forms of prey wrapping. We argue that prey wrapping at the capture site is an early adaptation of spider radiation into the aerial niche based on the presence of one form or the other in most taxa foraging above ground. Further, the extreme similarity of form of prey wrapping in higher spiders which build aerial webs is indicative of a stronger selective pressure for efficient prey handling than for actual prey capture behavior or web geometry.