490 
Psyche 
[December 
legs IV to direct the throw. In one form of immobilization wrapping 
the spider is in contact with the prey whilst throwing, whereas in 
the more complex form it throws swathes of silk over the prey from 
a distance. In an as yet unidentified species of Eriophora that we have 
studied, the spider actually turns to face away from the prey during 
non -con tact throwing. 
The behavior of Argiope argentata following the wrap/short bite 
couplet is important to our consideration of the functional aspects 
of immobilization wrapping. After the wrap/short bite sequence the 
spider leaves the prey in situ and returns to the hub. Eventually, 
after a variable period of time, it returns to the prey, cuts it out 
of the web and transports it to the hub. We believe that this period 
during which the spider leaves the prey and returns to active mon- 
itoring of the web has important implications for the functional inter- 
pretation of immobilization wrapping. 
After the long bite/wrap sequence the spider does not leave the 
prey in situ but proceeds to cut it from the web and carry it to the 
hub. If, however, there is already previously caught prey at the hub, 
the spider leaves the newly caught prey at the capture site and re- 
turns to feed on the previously caught prey. Peters (1931) notes 
that Araneus diadematus also leaves prey in situ if it already has 
prey at the hub. 
Functional considerations 
We have so far described araneids with one and two basic methods 
of attack (biting alone and biting or wrapping). In both cases there 
are distinct forms of employment of post immobilization wrapping. 
Eberhard (1967) has argued that post immobilization wrapping at 
the feeding site may have been the first type of wrapping behavior to 
appear, followed by post immobilization wrapping at the capture site. 
Immobilization wrapping could then be derived from post immobili- 
zation wrapping at the capture site. In terms of function Eberhard 
(ibid, p. 180) comments “wrapping may have originated as a post- 
immobilization process designed to free the spider for subsequent 
attacks”. 
It certainly seems reasonable to assume that post immobilization 
wrapping at the feeding site would ensure that the spider could make 
further attacks without dropping, or otherwise losing, the previously 
caught prey. (In fact, we have evidence that when Nephila clavipes 
omits this behavior, under the pressure of a rapid succession of prey, 
it can lose prey that it has already caught as it rushes to attack new 
prey; see page 497). Post immobilization wrapping at the capture 
