When DNA Fails Us: The Morphological Investigation of Marine Mammal Hair

All marine mammals, including pinnipeds, sea otters, and polar bears, are protected under the Marine Mammal Protection Act (MMPA). Certain species, such as sea otters, steller sea lions, ringed seals, etc. are additionally protected by the Endangered Species Act. The MMPA outlines strict regulations concerning the possession of any marine mammal product in the US with exceptions for Indigenous Alaskan tribes. If one is suspected of possessing illegal products, then identifying the species of origin is important because legal punishments are often more punitive for animals that have a higher protection status. In situations where the DNA is too degraded to sequence, morphological features are key to identification. Published materials for marine mammal hair morphology are limited compared to literature for terrestrial mammal hair. To characterize morphological features unique to marine mammals, guard hairs were removed from pelt clippings and macrostructures were analyzed. Light and scanning electron microscopy (SEM) were techniques used to investigate the cuticular scale patterns and inner medulla structure of 19 species from 7 different families: Otariidae, Phocidae, Ursidae, Odobenidae, Mustelidae, Felidae, and Leporidae. Differences in structure were identified between families in showing distinct medulla patterns. Although the medullary index varied with location on the body, the pattern remained constant. Possible distinctions between Otariid species were observed. Scale patterns also appeared distinctive between families, again with possible species variation. It was also observed that both medulla and scale patterns can change along the length of the hair. These distinguishing characteristics will be added to morphology databases important for forensic identification.