All eared seals are sexually dimorphic. Males are two to four times larger, have proportionately larger heads, necks, and chests (related to fighting), and may have a wider range of colors than females. Otariids as a group are somewhat smaller than true seals as a group. The head is dog-like, and both sexes have sharp, dog-like canine teeth. The eyes are large, irises are brown, and the pupils usually close to a pinhole in bright light. The postcanine teeth, a series of inter-
meshing points, are adapted for seizing prey, not for shearing or chewing. All species have small, cone-like external ears (hence the scientific name), unlike the true seals and walrus which have only an external auditory meatus (passageway). The vibrissae are well developed, white in adults, and 3-18 in (8-45 cm) long. The flippers are black and either hairless or have sparse hair. The pectoral muscles are well developed in both sexes and provide fore-flipper propulsion. Sea lions (Otariinae five genera, six species) have a pelage composed only of coarse guard hairs. The females are usually brown to light tan, whereas the males may vary from almost white to black. Fur seals (Arctocephalinae, two genera, nine species, two subspecies) have a pelage composed of guard hairs emerging from a dense, fine, brown, usually unseen under-fur. Fur seal females are usually grizzled gray (black when wet) with light bellies, and males vary from white to reddish to black, depending on the species. Pups are usually black. Females make loud, prolonged calls related to finding their young. Males make a variety of calls, including repeated pulses (like barks), and prolonged calls.
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