DISILVIO, BE; WEBB, JF; Villanova University; Villanova University: Some Observations on the Teeth of Mesopelagic Fishes

Scanning electron microscopy revealed variation in the morphology and arrangement of the teeth in representatives of nine genera of mesopelagic fishes belonging to the orders Stomiiformes (Argyropelecus, Cyclothone), Myctophiformes (Protocyctophus, Lampanyctus, Diaphus, Stenobrachius, Notoscopelus), Scorpaeniformes (Sebastolobus) and Beryciformes (Poromitra). Tooth profile, shape and size, mode of tooth attachment, tooth spacing and number of tooth rows were examined in the upper and/or lower jaws. These fishes demonstrate a remarkable degree of variation in tooth morphology, with tooth size ranging from <35 �m (Poromitra sp.), to >200 �m (Cyclothone sp.). The spacing of teeth ranging from adjacent (Cyclothone sp.) to widely spaced (Argyropelecus sp.); the surface texture of most of the species was smooth, but two species had either distinctly ridged (Cyclothone sp.) or longitudinally grooved teeth (Lampanyctus tenuiformis). Only the myctophids examined had multiple rows of teeth, which, with one exception (L. tenuiformis), demonstrated an offset arrangement. With the exception of myctophids in two genera that had flattened teeth (Stenobrachius, Notoscopelus), the rest of the fish examined had teeth with a conical profile. Tooth morphology in this selection of mesopelagic fishes is quite diverse suggesting that their feeding strategies might be diverse as well.