Ribbon seal

The ribbon seal (Histriophoca fasciata) is a medium-sized pinniped from the true seal family (Phocidae). A seasonally ice-bound species, it is found in the Arctic and Subarctic regions of the North Pacific Ocean, notably in the Bering Sea and Sea of Okhotsk. It is distinguished by its striking coloration, with two wide white strips and two white circles against dark brown or black fur. It is the only living species in the genus Histriophoca, although a possible fossil species, H. alekseevi, has been described from the Miocene of Moldova. Adult seals are recognizable by their black skin, which carries four white markings: a strip around the neck, one around the tail and a circular marking on each body side, which encloses the front fins. The contrast is particularly strong with the males, while with females the difference in color between bright and dark portions is often less conspicuous. Newborn ribbon seal pups have white natal fur. After moulting their natal fur, their color changes to blue-grey on their backs and silvery beneath. Over the course of three years, portions of the fur become darker and others brighter after every molt, and only at the age of four years does the striped pattern emerge. The ribbon seal has a short snout with broad, deep internal nares and large, rounded, front-facing orbits. Like other phocids, it possesses enlarged auditory bullae and lacks a sagittal crest. The ribbon seal has curved, widely spaced dentition and smaller canines than other phocid species. The ribbon seal has a large inflatable air sac that is connected to the trachea and extends on the right side over the ribs. It is larger in males than in females, and it is thought that it is used to produce underwater vocalizations, perhaps for attracting a mate. Unlike other pinnipeds, the ribbon seal lacks the lobes that divide the lungs into smaller compartments. The ribbon seal can grow to a length of about and a weight of , with males being larger than females. The main predators of ribbon seals include great white sharks and orcas.