Meeting Abstract
51.4 Monday, Jan. 5 Lateral line-mediated prey detection in the Lake Malawi cichlid, Aulonocara hansbaenchi BASSETT, Daniel K; WEBB, Jacqueline F*; University of Rhode Island; University of Rhode Island jacqueline_webb@mail.uri.edu
Among fishes, the lateral line system plays a role in navigation, communication, predator avoidance, and prey detection, but the functional significance of variation in lateral line morphology is still not well-understood. Peacock cichlids of Lake Malawi (Aulonocara spp.) have widened lateral line canals, a morphology that enhances sensitivity to local water flows such as those generated by invertebrate prey. We tested the hypothesis that the lateral line system mediates prey detection in A. hansbaenschi. Six live and six fresh frozen (dead) brine shrimp were tethered in pairs in six petri dishes randomly placed in a 3X4 grid in the sandy substrate of an experimental tank. Standard digital video was used to describe prey detection behavior of individual fishes. At night, prey detection was generally preceded by a glide, and a pause and a 180 swimming reversal that re-positions the prey under the mandible prior to strike. During the day, prey detection tended to be preceded by a glide and a change in orientation. More live (vs. dead) prey were eaten at night, but during the day high numbers of both live and dead prey were eaten. Deactivation of the lateral line with cobalt chloride virtually eliminates the ability to detect live prey at night. Thus, we have demonstrated that A. hansbaenschi: 1) can feed nocturnally, 2) uses its lateral line system for the detection of hydrodynamic stimuli produced by live prey especially at night, and 3) alters its prey search and detection behavior when feeding on the same prey under light and dark conditions. The widened lateral line canal morphology in Aulonocara is convergent with that in taxa in more than a dozen families, some of which are known to feed on infaunal benthic prey or in midwater. Aulonocara will be developed as a model to understand the developmental and genetic bases for functional evolution of the lateral line system among fishes.
