Meeting Abstract
89.6 Sunday, Jan. 6 Effects of limb autotomy on locomotor performance of ghost crabs PFEIFFENBERGER, JA*; HSIEH, ST; Temple University; Temple University jpfeiffe@temple.edu
Autotomy, or limb loss, is a mechanism frequently used in response to aggressive inter- and intra-specific interactions, despite the possibility of negatively impacting fitness by hampering an animal’s ability to run, walk, or swim. Although Atlantic ghost crabs (Ocypode quadrata) are decapods, they use only eight of their ten legs when running and maneuvering. Differential use of the locomotor limbs may thereby place different amounts of functional importance on each of the limbs, requiring functional compensation for limb loss and/or a decrease in locomotor performance. The goal of this study was to quantify natural patterns and frequencies of limb loss, and to determine whether these patterns reflect the ability for crabs to compensate more effectively for the absence of certain limbs over others. Patterns of limb loss were quantified at five independent sites in Brevard County, Florida for 159 crabs over 22 nights. Interestingly, limb loss was infrequent among the nocturnally-active individuals. We used the highest (3rd leg: 37.5 %) and lowest (1st leg; 6.25%) observed limb loss frequencies to define the two autotomy treatments for laboratory-based performance studies. Each crab was first run with all limbs intact to serve as its own control before limb autotomy. Ten crabs (five per treatment) were run on a track filled with 200 µm diameter glass particles characteristic of a fine sand beach, and filmed with a single dorsal view at 250 fps (Redlake). The three fastest, constant velocity runs per individual for treatment and control were analyzed for differences in limb use and performance. Results indicate that limb loss reduces sprint speed, in comparison to when running with all limbs intact. How limb autotomy affects function of the remaining limbs, as well as its potential impact on its behavioral ecology will be discussed.
