Meeting Abstract
The mechanosensory lateral line system of deep-sea fishes, especially that of the Stomiiformes, is relatively unknown. Unlike melamphaids and gadiforms, which have obvious widened cranial lateral line canals with large neuromasts, stomiiforms are reported to have less prominent (and fewer) lateral line canals and few superficial neuromasts. We examined two important, commonly caught, and widely distributed stomiiform taxa: hatchetfishes (Argyropelecus: Sternoptychidae) and bristlemouths (Cyclothone: Gonostomatidae). Fish were recently collected at sea (Tucker trawl) or obtained from museum collections and examined using clearing and staining, whole mount hematoxylin staining, histology, µCT imaging, and SEM. Contrary to Handrick (1901), who reported the presence of an unusually small number of neuromasts in Argyropelecus, we observed discrete vertical lines and clusters of small, densely placed superficial neuromasts above and below the eye, on the cheek, along the mandible, and in lines on trunk. In addition, canal neuromasts were identified in the partially enclosed and largely unossified supraorbital canals. In contrast,Cyclothone has no cranial lateral line canals, but has small superficial neuromasts in similar locations on the head and trunk, although they are not as highly proliferated as in Argyropelecus. The ability to obtain high quality specimens is critical because the skin of these fishes is extremely thin and easily subject to damage during collection. Our novel observations have radically changed our view of the non-visual sensory biology of these important fishes of the deep sea. Funded by an NSF Graduate Research Fellowship (Award #ADW03561), an ANMH Lerner Gray Fund Award, and the University of Rhode Island.
