Meeting Abstract

P3.86  Monday, Jan. 6 15:30  The fat and the furriest: Morphological changes in harp seal fur with ontogeny GMUCA, N*; PEARSON, LE; BURNS, JM; LIWANAG, HEM; Adelphi University; University of Alaska Fairbanks; University of Alaska Anchorage; Adelphi University nataliagmuca@mail.adelphi.edu

For mammals in polar regions, the extreme cold of the environment presents a constant challenge to thermal homeostasis. The harp seal (Pagophilus groenlandicus) is a true seal species whose range extends from the North Atlantic to Arctic Oceans. Adult harp seals primarily use blubber for insulation, but newborn harp seals instead rely on their fur coat while their blubber layer develops. Harp seal pups are weaned abruptly, less than two weeks after birth, and must learn to swim and dive in frigid waters on their own. This study examined how the morphological characteristics of harp seal fur change as the animals age. We compared hair length, hair circularity, and hair density for neonates (1 day old, N=7), thin whitecoats (4 days old, N=3), fat whitecoats (9 days old, N=4), newly weaned pups (2 weeks old, N=5), molted pups (3 weeks old, N=4), and adult harp seals (N=4). Hairs were shorter (P<0.001) and flatter (P=0.001) in older animals. Additionally, hair density decreased with age, in terms of the average number of hair bundles per unit area as well as in the average number of underhairs present in any given bundle. All of these morphological changes were associated with a reduction in the insulative function of the pelt. These results are consistent with known evolutionary patterns of fur morphology associated with the transition from fur to blubber in aquatic species, yet this is the first time these morphological differences have been demonstrated across age classes within a single species.