Figure 1.

Navigation by amblypygids is hypothesized to rely on sensory information derived from sensilla on the antenniform legs. (A) Image of P. marginemaculatus that shows the (L₁) antenniform legs and (P) raptorial pedipalps. (B) SEM of the distal tip of an antenniform leg of P. marginemaculatus, which shows three types of sensilla: c, club sensillum (contact chemosensory); p, multiporous sensillum (olfactory); and b, bristle (mechanosensory and contact chemosensory). (C) In the laboratory subjects readily utilize an artificial shelter. Shown here are nocturnal return routes for two subjects (recorded every 2 s) in a 1-m² arena. Four kinematic variables used to characterize the paths are listed: c, a circuity index, is the straight line distance (dashed line) from the start point of the return route to the shelter (large open circle) divided by the actual distance traveled; g, a goal orientation index, measures the directedness of the path with respect to the shelter (described in Bak-Coleman et al., 2013); s, the mean linear speed (mm s^-1); and f, the frequency of pauses (per minute) in motion (small filled circles) on the route to the shelter.