Marine mammals are a diverse group of species that include cetaceans, pinnipeds, sirenians, sea otters, and polar bears. The cetaceans consist of two major groups with different physiology and anatomy: toothed whales (Odontocetes) and baleen whales (Mysticetes). The pinnipeds consist of three major groups: true seals (Phocidae), eared seals (Otariidae), and walruses (Odobenidae). Sirenians (Sirenidae) are of a single family that includes manatees and dugongs. The sea otter (Enhydra lutris) is a marine member of the Mustelidae, and the polar bear (Ursus maritimus) is the only member of the Ursidae that is considered marine.
Few pharmaceuticals or vaccines are approved for use in marine mammals. Many recommendations can be made based on personal experience or published reports, but clinicians should be cautious in their application.