The role of numerical competence in a specialized predatory strategy of an araneophagic spider

Although a wide range of vertebrates have been considered in research on numerical competence, little is known about the role of number-related decisions in the predatory strategies of invertebrates. Here, we investigate how numerical competence is expressed in a highly specialized predatory strategy adopted by the small juveniles of Portia africana when practicing communal predation, with the prey being another spider, Oecobius amboseli. Two or more P. africana juveniles sometimes settle by the same oecobiid nest and then share the meal after one individual captures the oecobiid. Experiments were designed to clarify how these predators use number-related cues in conjunction with non-numerical cues when deciding whether to settle at a nest. We used lures (dead spiders positioned in lifelike posture) arranged in a series of 24 different scenes defined by the type, configuration and especially number of lures. On the whole, our findings suggest that P. africana juveniles base settling decisions on the specific number of already settled conspecific juveniles at the nest and express a preference for settling when the number is one instead of zero, two or three. By varying the size of the already settled juveniles and their positions around the nest, we show that factors related to continuous variables and stimulus configuration are unlikely explanations for our findings.     

THE USE OF ROLEPLAYING JOB INTERVIEWS WITH JOB CORPS FEMALES

Observation of the schism between employers and disadvantaged females, leads to the preparation of counselees for job interviews and exploration of the world of work with them. By chance, roleplaying a job interview was used during a group guidance session with Job Corps females, and the comparative success encountered with the technique encouraged this investigation. As a technique, it was found to be flexible, adaptable, and timesaving. It was of benefit to the counselor in six areas, and students indicated that they found the technique of value as a means of preparation for a real job interview, acquainting them with the scope of their communications problems and reducing these shortcomings.