Image: The Steller's sea cow. (

Steller's Sea Cow

(Hidrodamalis gigas)


The Steller’s sea cow became extinct in 1768, only 27 years after its discovery. The species was described after becoming extinct.

Giant Denizen of the Bering Sea

The following is a textual transcription of the Steller’s sea cow account in the book “The Annihilation of Nature: human extinction of birds and mammals” by Ceballos et al (2015). Available at John Hopkin’s Press and Amazon.

Steller’s sea cow, a close relative of manatees, was a huge animal. Adults weighed more than 8,000 kilograms (17,600 pounds) and measured up to 8 meters (26 feet) in length. The species was discovered by perhaps the most ambitious scientific expedition of the eighteenth century, led by the explorer Vitus Bering and sponsored by the Russian Academy of Sciences. The expedition’s goal was to explore the lands and waters of the Russian Far East.

In 1741, numerous problems beset the expedition and illness afflicted many of the crew. Bering himself died that year on what would later be known as Bering Island in the Bering Strait. Another twenty-eight members of his crew also perished on that barren piece of land. The doctor-naturalist on board was Georg W. Steller, who discovered the sea cow that bears his name. This stunning animal was apparently very abundant in the cold waters near the island. Steller wrote that there were “quite the many Manatee near shore in the water, which I had before never seen,” and also mentioned that “these animals are fond of shallow sandy places along the seashore, but they like specially to live around the mouths of rivers and creeks, for they love fresh running water.”

In the 1700s the sea cows were already restricted to a small geographic range. Later research indicated that the Steller were a relic of a larger distribution that had existed a few hundred thousand years earlier. But Steller’s discovery marked the beginning of the end for the huge sea cows. Subsequent expeditions indiscriminately hunted the virtually helpless animals for their meat, fat, oil, and hides. A naturalist on an expedition in 1802 wrote, “Sea-cows were formerly frequent at the coast of Kamchatka and the Aleutian Islands, but in the year 1768 the last animal of this species was killed, and since then none has been seen any more.” That last individual was killed only twenty-seven years after Steller discovered the species.


The Steller's sea cow was once widespread along the North Pacific Coast, reaching as far south as Japan and California.


The Steller's sea cow is extinct due to overexploitation. It used to be hunt for its subcutaneous fat. The population was quickly wiped out by sailors, seal hunters, as well as fur traders. Remarkably, its demise was also caused by an extinction cascade. Fur traders exterminated sea otters. In the absence of otters, the sea urchin population exploded and decimated the kelp forest that was the main food for the sea cows.

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