Meeting Abstract
Some vertebrates and many arthropods can voluntarily lose an appendage (i.e., autotomize) during antagonistic encounters. Yet, how animals alter limb use to accommodate the loss of locomotor limbs is poorly understood. A recent study showed intact wolf spiders using an alternating tetrapod gait, and switching to a more stable alternating tripod gait after autotomy of two limbs. We hypothesized that spiders use learning to expedite autotomy-induced gait changes and will switch gaits more rapidly after a previous limb loss event. We acquired hatchling tarantulas (Davus pentaloris) that had never lost limbs prior to our study. We recorded dorsal views at 500 fps (Photron SA-3), first with all limbs intact (control) and then following removal of two limbs from one tetrapod. Upon limb regeneration, we recorded more control trials and then autotomized the same two limbs. We calculated relative limb phases to categorize the spiders’ gaits. Autotomy had no significant effect on running speed (F=1.32, p=0.28) and basic stride kinematics were different from control only following the first autotomy. Duty factor did not change (F = 1.51, p = 0.22) among all treatments. However, stride length increased (F = 12.56, p < 0.0001) and stride frequency decreased (F = 8.00, p < 0.0001) following the first autotomy only. In control trials, the alternating tetrapod gait was used in the majority of the trials (32 of 42). Following limb autotomy, we observed a temporal shift from using the ablated tetrapod gait to the alternating tripod gait; but the rate of this shift did not appear to differ between the autotomy treatments. These results suggest that there are multiple strategies for adapting to limb loss and that learning is not necessarily a critical component of this compensatory process.
