This white coat is normally completely shed by 5 weeks of age. Width of the ribbons is quite variable, and on some seals they fuse together. The pattern tends to be similar on males and females. The background color in males is very dark, almost black. In females, the background is a lighter brown, resulting in less obvious contrast with the white bands.
Ribbon seals have very large eyes which seem uniformly black.
The whiskers are somewhat flattened in cross section. Teeth are weakly rooted and relatively small compared to those of harbor seals. Normally there are 34 teeth composed of three upper and two lower incisors, one upper and lower canine, four upper and lower postcanines, and one upper and lower molar on each side. The trachea or windpipe is unique, as the anterior part is broadly connected to an air sac which is present in males and females, though it is considerably more developed in males and sometimes absent in females. The air sac overlies the ribs on the right side of the body.