Abstracts

Displacement experiments with amblypygids, nocturnalarachnids that inhabit the tropics and subtropics, revealed thatthey are rather extraordinary navigators and that their abilitiesare severely impeded when access to olfactory information isexperimentally abolished. These results and the fact thatamblypygids possess exceptionally large mushroom bodies, brainregions that process olfactory and, perhaps, spatial informationled to the hypothesis that olfaction facilitates their navigationbehavior. The amblypygid Phrynus marginemaculatus wanders nightlyand shows strong shelter fidelity in a laboratory arena. Here,individual subjects were trained over a 26-night session in asquare arena that contained two shelters to determine the extent towhich shelter recognition is dictated by odor. The target shelterwas positioned at a specific location in the arena near an acrylicwell that contained 15 l of geraniol. The other shelter waslikewise positioned at a particular location in the arena, but nearan acrylic well that contained 15 l of water. The sessionconsisted of nights on which the entrance to the target shelter wasopen and the entrance to the other shelter was closed, referred toas forced choice trials, and nights on which a subject had accessto both shelters, referred to as probe trials. Probe trialsinvolved manipulations of the locations of the shelters and theirassociated acrylic wells after a subject emerged from the targetshelter. The probes consisted of three types of manipulations:control manipulations in which the shelters and associated acrylicwells were removed and replaced with identical shelters and dishesin their original locations; manipulations in which the positionsof the two acrylic wells were swapped; and manipulations in whichboth shelters and their respective acrylic wells were moved fromtheir original, trained locations. The odor-cued shelter was chosenin more than 90 percent of the control probes, but in the other twoprobe conditions shelters appear to have been chosen randomly.Thus, shelter choice was not dictated by odor. In addition,subjects did not rely primarily on path integration, a commonlyapplied navigation strategy in arthropods, as they did not chosethe shelter in the original location of the odor-cued shelter inprobes where only the positions of the acrylic wells were swapped.Instead, the results suggest that amblypygids, like ants, may use aconfiguration of cues to relocate and identify ashelter.Advisors/Committee Members: Wiegmann, Daniel (Advisor).