Meeting Abstract

P2.8  Wednesday, Jan. 5  On false mouths and pharyngeal architecture: The interesting case of Pseudostomella (Gastrotricha, Macrodasyida) HOCHBERG, R; Univ. of Massachusetts, Lowell rick_hochberg@uml.edu

Gastrotrichs live in a miniature environment characterized by extremely low Reynolds numbers. The morphology of the gastrotrich feeding system is thus adapted to overcome viscosity and enhance prey capture. An investigation of head structure in species of Pseudostomella, which possess a highly unusual cephalic morphology, was performed to gain insight into the functional morphology of feeding in these unusual gastrotrichs. Electron microscopy and confocal laser scanning microscopy were used to explore mouth profile, pharynx ultrastructure, cephalic muscle topology and pharyngeal innervation. Results indicate that species of Pseudostomella share a common pharyngeal ultrastructure with other species of Thaumastodermatidae, but have secondarily lost their oral hood and expanded their pharyngeal walls and somatic musculature to form a prebuccal apparatus. The adaptive significance of this new head morphology is discussed with reference to the trophic ecology of the interstitial environment.