Ecology and behaviour in Portia schultzii, with notes on related species (Araneae, Salticidae)

Field observations of Portia schultzii, a web-building jumping spider from Kenya, Africa, reveal that it commonly inhabits the dense webs of Ischnothele karschi, a diplurid spider. As a detritus mimic, this spider is inconspicuous whether in a web or on the move. Laboratory studies show that it readily catches a variety of prey-spiders and insects (mainly Drosophila) in its own webs, in I. karschi and other alien webs, as well as in non-web situations. Although the basic, visually-directed, predatory sequence conforms to that of the typical salticids, several derived features, such as the extremely slow and specialised locomotory movements, long periods of immobility in a cryptic posture, the web strategies of 'quivering' and 'dropping', and shorter visual discriminatory distances (not more than 10 cm) than most other salticids, enable this spider to exploit a web environment.