Meeting Abstract
147.1 Monday, Jan. 7 Running performance and gait kinematics of a sand-adapted arachnid, Galeodes granti MAYORGA, O*; YIP, V; MAZOUCHOVA, N; GOLDMAN, DI; SPAGNA, JC; William Paterson University; Georgia Institute of Technology; Georgia Institute of Technology; Georgia Institute of Technology; William Paterson University spagnaj@wpunj.edu
Solifuges (“camel spiders”; Arachnida: Solifugae) typically live in desert environments and run quickly on sandy substrates. To test the hypothesis that Solifugae are well-adapted to running on sand, we compared the running performance of the solifuge Galeodes granti, to three cockroaches: B. discoidalis and immature B. discoidalis, which are tropical, and A. investigata, a desert species. We then analyzed the solifuges’ gait characteristics and compared them to those of spiders and scorpions. The animals were placed on a platform covered with a uniform layer of 0.3 mm diameter glass particles, similar to natural sand, ~1 cm deep. The platform was adjusted to four angles (0, 5, 10, 15, 20 degrees) and locomotion bouts were recorded using a high-speed camera. Comparisons of slopes of speed vs. angle showed that with increases in angle, solifuge performance was maintained, while the other species slowed (ANCOVA, p < 0.05). Each solifuge video (n=3 individuals, mean mass 1.7g, 34 total runs) was analyzed to measure periods of ground contact and swing phase for each leg across two step-cycles. These indicated that the solifuges used their 6 rear legs in alternating sets of three, analogous to the insect ‘alternating tripod’ gait. Average speed was 12 cm/sec, stride frequency was approximately 3 strides/sec, duty factor was 0.86. , and tripod synchrony factor was 0.62. Regression analysis revealed a significant relationship (p < 0.01) between speed and frequency, but not between speed and duty factor, or speed and stride length. The gait patterns of solifuges are more similar to those of scorpions than to comparably-sized spiders, which may reflect adaptation to their shared sandy habitats.
