Ribbon Seal Histriophoca fasciata

Abstract

This chapter examines the characteristics, taxonomy, distribution, and behavior of the ribbon seal, which is one of the least well known of all the world's pinnipeds. The species has been placed in the genus Phoca based on cranial morphology but molecular studies indicate that ribbon seals belong in the separate genus, Histriophoca. Pups are born with a long, white pelage called lanugo, and for the first year after the lanugo is shed their coat is silver–gray with a dark blue–black back. Older seals have a dark background with a set of light bands encircling the head, the posterior trunk, and each front flipper. The distribution of ribbon seals is restricted to the northern North Pacific Ocean, where they are seen most commonly in the Okhotsk and Bering seas. The ribbon seal is considered to be a pagophilic (ice-loving) species, and sea ice provides them an essential platform that is used for pupping, nursing their pups, and molting. Compared with other seals, the eyes of ribbon seals are quite large. However, they seem to have poor vision in air so this may be an adaptation for improved eyesight under water. Ribbon seals have not been the subjects of detailed physiological studies that have recently been done on many other pinnipeds. Some studies of respiratory physiology and blood parameters suggest adaptations for a pelagic existence and deep diving. They are infrequently caught incidental to commercial fishing operations in Alaska and on the high seas.