Portia spiders have amazingly sophisticated hunting behaviors for an invertebrate.
Portia uses aggressive mimicry against, and catches, just about every kind of web-building spider imaginable, as long as it is in a size range of from about 1/l0th to twice Portia’s size (Jackson & Hallas 1986). Being able to make so many different kinds of signals is important, because how Portia’s prey, another spider, interprets web signals may vary considerably depending on the species to which it belongs, its sex, age, previous experience and feeding state.
An ability to make so many different signals, however, raises the next question. How does Portia derive the appropriate signals for each of its many victims from its enormous repertoire? Two basic methods appear to be critical (Wilcox & Jackson 1998): 1) using specific genetically pre-programmed signals when cues from some of its more common prey species are detected; and 2) flexible adjustment of signals in response to feedback from the prey (i.e., trial-and-error derivation of appropriate signals). The first, using pre-programmed signals, is consistent with the popular portrayal of spiders as animals governed by instinct, but trial and error is an example of problem-solving behaviour and less expected in a spider.
