Steller’s sea cow size
The Steller’s Sea Cow (Hydrodamalis gigas) is an extinct species of sirenian native to the Bering Sea. Its small head was perfectly adapted to a huge body for taking and eating marine plants in its mouth, and its body ends in a forked tail like a whale. The tail of the Steller’s Sea Cow was somewhat similar to that of a dugong. Historically, it is the largest member of the order Sirenia, which also includes its close relatives the dugong (Dugong dugon) and the manatees (Trichechus spp.). In the past, it was widespread in the North Pacific, but its distribution was restricted to the isolated islands of the uninhabited Cormandel Islands. It was first described in 1741 by Georg Wilhelm Steller, medical director of the expedition led by explorer Vitus Bering. Within 27 years of European discovery, the slow-moving Steller's Sea Cow was driven to extinction.
Adults were at least 8 m (26 ft) long and up to 9 m (30 ft) long; significantly larger than the extant dugongs; but there are two estimates of their weight in Steller's work: 4 tonnes and 24.3 tonnes. Where these figures are available, the true value is estimated to be between 8 and 10 tonnes. It looked a bit like a large seal, but has two thick faces, a whale-like face and tail. According to Steller, "This animal never comes to shore, it always lives in the water, its skin is dark and thick, like the bark of an old tree... They had no teeth, only two white bones, one on top and one on the bottom. The Sea cows there were also very slow swimmers, apparently unable to dive to the bottom of the ocean.
The Steller’s Sea Cow is a member of the genus Hydrodamalis, a group of large manatees whose sister taxon is Dusisiren. Like the Steller's Sea Cow, Dusisiren's ancestors lived in warmer climates before migrating to the colder climates of the North Pacific. 4 to 8 meters. The Steller's Sea Cow is a member of the family Dugongidae, the only surviving member of the family and the Steller's Sea Cow's closest relative is the dugong (dugong).
The Steller's Sea Cow is a descendant of the Cuesta sea cow (H. cuestae), which has disappeared from the west coast of North America, particularly in California. The Cuesta sea cow is thought to have become extinct due to the onset of the Quaternary glaciation and the subsequent cooling of the oceans. Many groups have become extinct, but the Steller's sea cow species have adapted to colder conditions. Manatees and Steller's Sea Cow are more common than Cuesta's sea cows, leading some to believe that the Takigawa manatee is its own species.
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