monk seals are part of the family phocidae (earless seals), the members of which are characterized by their lack of external ears, the inability to rotate the hind flippers under the body, and shed their hair and the outer layer of their skin in an annual molt. monk seals as a whole vary minutely in size, with all adults measuring on average and . they exhibit sexual dimorphism, in that the males are slightly larger than females, with the exception of the hawaiian monk seal, where females are larger. its white belly, gray coat, and slender physique distinguish it from the harbor seal ("phoca vitulina"), another earless seal. much like elephant seals, they shed their hair and the outer layer of their skin in an annual molt.