Meeting Abstract

P1.145  Monday, Jan. 4  3-dimensional kinematics of prey capture in tarantulas KELSEY, TJ*; ASHLEY-ROSS, MA; Wake Forest University rossma@wfu.edu

Tarantulas (family Theraphosidae) are the largest extant spiders (up to 10 inches legspan) and the most speciose family (~800 species) of the suborder Mygalomorphae, which includes the most primitive members of the arachnids. None of the mygalomorphs spin prey-catching webs; tarantulas are sit-and-wait predators that use their appendages and chelicerae-injected venom to capture and subdue their prey. Little is known about the mechanics of prey capture in these extraordinarily fast animals. We studied the kinematics of attacks using two high speed video cameras (500 frames/s) to track the movements of spiders during their attacks on crickets. We recorded a minimum of five strikes from at least three individuals of Mexican Red-Knee (Brachypelma smithi), Chilean Rose-Hair (Grammostola rosea), Guyana Pinktoe (Avicularia avicularia), Flagstaff Orange (Aphonopelma sp.), and Curly Hair (Brachypelma albopilosum) tarantulas. Small white dots were painted on the bottom of the spider legs, two per leg segment, for use as tracking points. A digitizing routine in MatLab was then used to track each point in order to make three-dimensional digital trajectories of each leg. Average time from initial movement of the legs to positioning the prey against the mouth was 250-300 ms. Smaller individuals tended to have much quicker attack sequences (<100 ms). Absolute strike distance varied with spider size; in general, the tarantulas tend to attack straight forward to minimize strike distance and decrease overall attack time. However, side-directed attacks are also common. Smaller individuals seem to have a much broader attacking range, even having the ability to make a complete 180 degree turn before apprehending the prey. Tarantulas are thus capable of extensive modulation of individual leg segment movements and timing.