Not long ago, Alaska had a manatee-like relative paddling through its waters. Steller’s sea cows were apparently delicious, explaining why they were quickly brought to extinction. If humans hadn’t exterminated this animal, we would have three sirenians still gliding through our oceans. Instead, there are only two: manatees and dugongs.
The name Sirenia comes from the Greek term "sirens" of the sea. Lonely sailors apparently mistook the animals for women while out on long fishing hauls. Manatees and dugongs are calm, slow-moving marine mammals that belong to the same classification as Stellar's sea cow. The animals feed on seagrass or floating plants in the water column.
Manatees are composed of three living species dispersed through the Amazon, West Africa, the Southern United States and the Caribbean. Dugongs live along the coastlines of Asia and Australia. Steller’s sea cows were discovered in Alaskan oceans in 1741 and were declared extinct in 1768. Two things are responsible for the extinction of the animal: direct hunting of the sea cows and hunting of sea otters, which allowed sustenance of kelp beds in which the sea cows fed.
The rapid extinction of the Steller’s sea cow provides just another example of human’s tendency of acting for quick gains rather than long-term sustainability. Over thousands of years, Steller’s sea cows perfected their ability to thrive in Alaskan waters through the dance of genetic evolution. In just 27 years, humans wiped out all of these miraculous adaptations and the entirety of their genes. This is probably the greatest shame in extinction events caused by humans: elimination of beautifully adapted genes in the blink of an eye.
Many unique characteristics disappeared with the extinction of the Steller’s sea cow. The animal was considered the largest of all sirenians. The manatee-resembling animal had no external ears, paired nostrils at the tip of its plant-eating snout, and whiskers likely utilized to encounter its herbivorous diet. Likely toothless, but with a more flexible body than living sirenians, the animals were highly adapted for feeding in the cold waters of Alaska’s Bering Sea. A thick layer of skin and blubber armored the animal for its intense environment. Examination of the animal’s skeleton suggests that it was adapted to “walk” along the ocean bottom, with a similar movement to slow-moving sloths.
Like all other marine mammals, the Steller’s sea cow was amazingly tailored to tolerate huge amounts of water pressure, lack of access to a constant supply of air, and the ability to retain heat in a cold, liquid environment. Whales, pinnipeds, and sirenians have all miraculously adapted to the difficult conditions of the ocean. With every extinction of a species, we loose a profound amount of evolutionary work.
The Steller’s sea cow was a truly unique species, never to be mistaken for a siren again.