Scientific name: Hydrodamalis gigas Scientific classification:
Phylum: Chordata Class: Mammalia Order: Sirenia Family: Dugongidae
When did it become extinct? It became extinct in the year 1768, although it is possible that the species may have persisted for a few more years. Where did it live? The last populations of Steller's sea cow were known from some of the islands in the Bering Sea, just off the coast of the Kamchatka Peninsula.
In 1741, the St. Peter, captained by Vitus Bering, departed from Kamchatka. The mission was to find an eastern passage to North America. On board was a 32-year-old German
Steller's Sea Cow—At least 8 m long, Steller's sea cow was the largest marine animal apart from the whales, and it is the largest animal to have gone extinct in relatively recent times. (Phil Miller)
by the name of Georg Wilhelm Steller, who was the ship's official mineralogist. Steller also happened to be a physician and a very keen naturalist. His journey on the ship through the Bering Sea would be a remarkable one, on which he would make many zoological discoveries. Steller diligently documented everything he saw, and most of what we know about Steller's sea cow is thanks to the notes he and a crew mate, Sven Waxell, made in their journals.
The sea cows were observed around Bering Island and Copper Island, where they could be observed floating among and feeding on the vast marine forests of kelp that grew in the shallows around these islands. Steller's observations give us an insight into how this animal lived and what it looked like. Steller's sea cow was a huge animal and one of the biggest creatures to have become extinct in very recent times. It was very closely related to the dugongs and manatees, the unusual marine animals found in tropical rivers, estuaries, and shallow marine habitats around the world, but it was very much larger. Adults could grow to around 8 m, and the great bulk of the animal suggests weight in excess of 4,000 kg—possibly over 8,000 kg. They were gentle animals that apparently spent their time grazing on kelp—leaving great mounds of the seaweed washed up on the shore—and snoozing. In place of teeth, they had a bony ridge in their upper and lower jaws to grind the fibrous algae, and their forelimbs were stout flippers, which the animals could use to provide purchase on the rocky seabed when they were feeding in the very shallow coastal water. The animals' skin was rugged, thick, and black, and Steller likened it to the bark of an old tree. The downfall of Steller's sea cow was its flesh—a valuable commodity to the crew of the St. Peter, who were shipwrecked on Bering Island. Not only were these huge marine animals slow moving and gentle, but they also lived in family groups and appear to have been very curious. Steller observed them investigating the small boats of men who carried guns and spears to shoot and stab them. In what was a very wasteful strategy, the wounded animals were allowed to swim off in the hope that the surf and tide would bring them ashore. Often this was not the case, and the moribund animal would simply die and sink. The animals that were landed were butchered, and although the flesh had to be boiled for quite some time, it was very similar to beef in taste. When the survivors of the St. Peter were rescued along with barrels of Steller's sea cow meat, it was not long before whalers, fishermen, and hunters, attracted to the area for the bounteous amount of wildlife, turned their attention to these gentle animals to nourish them on their expeditions. Not only did they eat the meat and fat of this animal, but the oil from its blubber was also coveted because it gave off little smoke and odor when it was burned. The skin was processed to make a range of leather goods.
It has been suggested that even when Steller first observed the sea cow in 1741, it was already rare, its populations reduced to a fraction of their former strength by human hunting over thousands of years. Indeed, bones and fossils show that this species lived along much of the North Pacific coast, from Baja northward and down to northern Japan. What Steller discovered were the last populations of this impressive animal, which had survived in a remote, inhospitable area. As it was such a large animal, it is very likely that Steller's sea cow was a slow breeder, a fact that made it even more vulnerable to the effects of overhunt-ing. Whatever the state of the population of this animal when it was discovered, we know that by 1768, 27 years after it was described by Steller, it was extinct. It is possible that a few individuals survived in the shallow waters of other islands in the Bering Sea, but an expedition in the late eighteenth century did not find any sea cows. Even today, some people cling to the hope that Steller's sea cow survived into the modern day, with claims of sightings around the islands in the Bering Sea. Unfortunately, it is highly unlikely that such a large animal, which spent so much of its time at the surface, has escaped detection in an increasingly crowded world. Twenty-seventy years is an amazingly short amount of time for an animal to be wiped out, and it shows just how relentless humans can be in their extermination of other creatures.
♦ Steller, during his time on the St. Peter, documented hundreds of new species, including the northern fur seal (Callorhinus ursinus), the sea otter (Enhydra lutris), Steller's sea lion (Eumetopias jubatus), Steller's eider duck (Polysticta stelleri), and the spectacled cormorant (Phalacrocorax perspicillatus). All except the last species can still be seen today, but the populations of them all suffered terribly at the hands of hunters, who streamed into the area after Bering's ill-fated voyage. The spectacled cormorant, a large marine bird with a distinct unwillingness to take to the wing, was last seen around 1850.
♦ Along with the species that now bear his name, Steller also recorded other animals that have never been verified. One of these was described by him as the "sea ape," a marine animal with an unusual collection of features. It is impossible to know if the sea ape and others are animals we know today, but Steller's documented observational abilities leave us with the tantalizing possibility of other, as yet unknown animals swimming in the cold but productive waters of the Bering Sea.
♦ In December 1741, the St. Peter was forced to seek refuge from the atrocious conditions in the Bering Sea on what became known as Bering Island. Vitus Bering died of scurvy on this island, along with 28 of his crew. The survivors, with Steller among them, saw out the winter; they constructed a new vessel from the remains of the St. Peter and returned to Kamchatka. Back on the mainland, Steller spent the next two years exploring the vast peninsula of Kamchatka, documenting its animals, plants, and geology. He was eventually requested to return to St. Petersburg but died of an unknown fever on his way back.
Further Reading: Anderson, P. "Competition, Predation, and the Evolution and Extinction of Steller's Sea Cow Hydrodamalis gigas" Marine Mammal Science 11 (1995): 391-94; Scheffer, V. B. "The Weight of the Steller Sea Cow." Journal of Mammalogy 53 (1972): 912-14.
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