Meeting Abstract

80.6  Tuesday, Jan. 6 11:30  Scaling of ballistic tongue projection performance in chameleons ANDERSON, C.V.*; TOLLEY, K.A.; Brown University, Providence; South African National Biodiversity Institute, Cape Town

Body size and dimensions of organisms are known to have a profound impact on functional properties associated with animal movement. Predictions about how whole organism performance varies with body size can be derived from the scaling of morphological proportions. While the anatomy of many ectotherms scale with geometric similarity, a variety of selective pressures may act on an organism to produce allometric scaling patterns, which will alter predictions of whole organism performance. The feeding apparatus in chameleons, for instance, is known to scale with negative allometry with respect to snout-vent length, affording small chameleons with a proportionately larger feeding apparatus by weight than larger chameleons, both within and among species. To understand how this allometry affects whole organism performance, we examined the interspecific scaling patterns of tongue projection performance in chameleons. We analyzed over 275 feedings collected from 55 individuals representing 20 species in nine genera and a five-fold range in body length using phylogenetically corrected methods. We found that tongue projection length scaled with negative allometry with respect to both snout-vent length and jaw length, and that the peak acceleration of tongue projection and the peak mass-specific power required to power tongue projection both declined with increasing body size. This data shows that among species, smaller chameleons are able to project their tongue proportionately further than larger species, and are able to do so with higher accelerations and higher power output. These scaling relationships thus serve to increase the functional range and performance of the feeding apparatus of small chameleon species, which may be beneficial for animals with higher mass-specific metabolic rates than their larger relatives.