Females usually have two pairs of mammae. In males the testes are scrotal and the baculum is well-developed. The otariid skull is somewhat elongate and rounded, though rather bearlike in overall appearance. For example, the otariid skull has supraorbital processes and only slightly inflated tympanic bullae, the Odobenidae lack supraorbital processes and have moderately inflated bullae, and the Phocidae lack supraorbital processes and have well-inflated bullae. The number of upper molars varies within and among genera.
Eared seals inhabit arctic, temperate, and subtropical waters.
Their breeding habitat is exclusively marine, never freshwater. They shelter along sea coasts, in quiet bays, and on rocky, isolated islands. They may be active by both day and night. These seals protect themselves by tearing an adversary with their canine teeth, by hurling their weight against the adversary, or by diving and swimming away. They feed mainly on fish but also eat cephalopods and crustaceans.