The evolutionary origins of seals, sea lions and walruses is still unsettled science. Historical taxonomic studies suggest two potential lines of ancestry which include the Ursids (bears) and the Mustelids (otters, minks, ferrets…). While molecular and fossil evidence now appear to implicate an otter-like ancestor, some continue to cling to the “bear hypothesis.”
Collectively belonging to the Clade Pinnipedia, pinnipeds are carnivorous, fin-footed semiaquatic mammals. With the exception of the Baikal seal (Pusa sibrica), pinnipeds are marine mammals divided into three distinct groups. The Otariidae or true eared seals, possess ear flaps and a flexible hind flipper that allows for semi-coordinated movement on land. Familiar examples include the California sea lion, Zalophus californianus, who’s tendency to bark and play make them a favorite of zoos and marine parks. While significantly larger than sea lions, the Odobenidae have a similar body morphology, but are distinguished by their enormous hairless bodies and pronounced tusk-like canines. Commonly known as walruses, only one extant species remains. Sadly, their long-term viability is now threatened by the rapidly changing arctic climate. The significantly smaller Phocids, lack external ear flaps and have inflexible hind fins. Far more cumbersome on land than their sea lion brethren, “true-seals” are more aqua dynamic with their stubby clawed forelimbs and torpedo-like body.
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