P3.95 Friday, Jan. 6 Exploring the filter morphology and filtration mechanics in Mobulidae PAIG-TRAN, EWM*; KLEINTEICH, T; SUMMERS, AP; Univ. of Washington; Univ. of Washington; Univ. of Washington email@example.com
Filter feeding has evolved independently four separate times in three lineages of cartilaginous fishes (Lamiformes: Megachasma and Cetorhinus, Orectolobiformes: Rhincodon, and Mobulidae: Manta and Mobula). The independent evolution of filtering structures in elasmobranchs resulted in morphologically different filtering structures and presumably very different mechanisms for filtering food particles. Elasmobranch filter feeders have traditionally been predicted to use some form of sieve filtration; however, new mechanisms of particle capture in the filtering sharks have been proposed including engulfment filtering and cross flow filtration. The structure of Manta and Mobula filtering pads are very different compared to the filtering sharks. Manta and Mobula filter pads are chevron shaped structures composed of many rows of filtering lobes located on both sides of the gill filaments, facing toward the incoming flow of water and also toward the posterior buccal cavity. We performed scanning electron microscopy to examine the filtering pads of Manta birostris, Mobula tarapacana, and Mobula thurstoni and have found evidence that the surfaces of the lobes are covered with a blanket of cilia, which likely serve as a surface for capturing particles by hydrosol filtration. Using histology, we identified mucosal cells on the distal edge of the epithelium, presumably to provide a sticky coating for capturing food particles and for transferring to the esophagus. Finally, we identified the presence of denticles along the leading edge of the lobes, presumably to prevent degradation of the pads by large, fast-moving particles.