Meeting Abstract
P3.96 Sunday, Jan. 6 Open Wide! An Analysis of Interspecific Variation in Baleen Ultrastructure ZELLMER, N.*; BERTA, A.; San Diego State Univ.; San Diego State Univ. ntzellmer@gmail.com
Baleen whales (Cetacea: Mysticeti), some of the largest animals to have ever existed, reach their colossal size through the exploitation of a novel ecological niche using a unique adaptation: baleen. A rack of baleen consists of serially placed, horn-like plates that are fringed with bristles on the lingual side. The bristles act as a sieve allowing the whales to capture large batches of prey during a single feeding event. Despite our increased understanding of baleen whales, relatively little is known about the ultrastructure of baleen and how baleen differs between species. The objectives of this study were to 1) describe the interspecies variation in plate and bristle ultrastructure, and 2) describe interspecific variation in calcium salt deposition within the tissues of the baleen plate. Histological samples were taken from the labial side of plates from members of each of the major mysticete families. These samples were analyzed using an optical microscope and transmission electron microscopy. The Von Kossa staining method was used to show the deposition of calcium salts within the baleen plates. Basic structure and patterns were described for each species and interspecies variation was contrasted. Preliminary results show striking interspecific differences in the ultrastructure of the baleen plates. The tubules of the sei whale are a uniform, circular shape while they are variably sized and rectangular in humpback whale plates. There are also differences in the organization and thickness of the horny matrix; the sei whale has a thick, outer horny wall, which is completely absent in the minke whale. The patterns of calcium salt deposition within the tissues of the plates also showed interspecific variation. Further analysis of the patterns found in baleen ultrastructure will elucidate evolutionary and ecological relationships among these unique organisms.
