Meeting Abstract

79.1  Sunday, Jan. 6  Widespread distribution of the palatal organ across Cypriniformes suggests multiple roles in feeding HERNANDEZ, LP; George Washington Univ, Washington DC phernand@gwu.edu

The cypriniform palatal organ has long been thought to play a role in selectively feeding on the benthos. Composed of a dorsal mass of muscle fibers that spans the entire buccal roof it is strongly tied to the branchial elements laterally. Previous work on carp and goldfish has shown that this taste bud-studded muscular pad produces localized protrusions that are used to sort and select edible items while bottom feeding. While the neurobiology and physiology of palatal organ function in the goldfish has been well described, there is little data on palatal organ functional morphology across Cypriniformes. While previous reports have suggested that this important feeding structure is limited in its distribution these data show it is present in nine subfamilies of Cypriniformes. Importantly, an obvious palatal organ was present in species that are known to feed within the water column. Ontogenetic data show that this structure forms early in development. Moreover, data from miniaturized species (e.g. Paedocypris), in which many morphological structures are commonly lost, show that even these species have a patent palatal organ. To date the palatal organ is proposed to function solely to selectively feed on the benthos. While sorting during benthic feeding may have been the primitive function, it is likely that the palatal organ has secondarily become adapted for suction generation during the course of cypriniform evolution. Data is presented on muscular architecture and myosin composition of palatal organs of species within 9 subfamilies. Contrary to previously published results all species examined have some type of palatal organ. Although not as well developed or highly innervated as that of goldfish, a complex mesh of predominantly fast muscle fibers characterized nearly all cypriniform palatal organs.