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Steller’s Sea Cow

The Steller’s sea cow, the largest member of order Sirenia, is an extinct marine mammal. It was one of the largest mammals, along with wheals, which have existed during the Holocene epoch. This animal got its name from Georg Wilhelm Steller, who first described this species in 1741. This species went extinct just after 26-27 years since it was first discovered – around 1768.


Scientific classification

Kingdom Animalia
Phylum Chordata
Class Mammalia
Order Sirenia
Family Dugongidae
Subfamily Hydrodamalinae
Genus Hydrodamalis
Species H. gigas
Scientific name Hydrodamalis gigas

Quick Facts

Closest Relatives The dugong (Dugong dugon), and the manatees (Trichechus spp.).
Size 8 to 9 meters in length
Weight 8 to 10 tons
Diet Kelp, sea grasses and algae
Colour Grey, brown and black.
Habitat Arctic tundra
Average Litter Size 1


The body structure of Steller’s sea cow was quite like a large seal, but they had two sturdy forelimbs and a whale-like fluke. Their head was small compared to their body size. Their mouth was small and toothless. They also had double lips – both above and below.


Fossil samples suggest that this species was found along the North Pacific coast – extending south to Japan and west coast of the United States.

Interesting Facts

  • In 2012, Icelandic-French artist Etienne de France made a film called Tales of a Sea Cow. The film deals with a fictional re-discovery of Steller’s sea cows off the coast of Greenland. Tales of a Sea Cow was showcased in public institutes like universities and art museums across Europe. Annick Buread, an art critic, called the movie a “tongue in cheek and joyous but unsettling fable”.
  • A Russian explorer team, in 2011, provided a DNA sequence from several specimens that paved the way for its highly ambitious cloning project.
  • Yakolev, a first-hand observer of the Sea Cow, claimed that killing sea cows was forbidden by order on the Komandorskiye Islands in 1755.

Behavior and Adaptation

Sea cows were meek and gentle. They were slow swimmers and, in fact, historical account suggests that it was difficult for them to get completely submerged. Steller, in his description, suggested that they utilized their forelimbs for tasks like swimming, walking on the shallow waters of the ocean, fighting and even digging for algae.

Steller described that Sea cows were found in large herds. But later it was hypothesized that their number were small in a limited range when it was first discovered. Zoologist Leonhard Hess Stejneger estimated that there were less than 1500 specimens when it was first discovered by Georg Wilhelm Steller.

Causes of Extinction

Seal hunters, sailors and fur traders are believed to be largely responsible for their extinction. It has been noted that the extinction of the Sea cow has been triggered just by hunting for their meat and skin. They were also vulnerable for their subcutaneous fat that was used as butter. It fact, the fat was also used for oil lamps that did not produce any odor. Their skin was used to make boats. This species went extinct by 1768. Given its rapid elimination from its native range, it is possible that the aboriginal hunting was behind their extinction.

Some researchers argue that the decline of this species might have come as an indirect effect of Sea Otter killings by aboriginal people from the inland regions. It is possible that increased sea urchins (Sea Otter’s food) reduced the availability of kelp, which was the primary food of Sea cow. This species was limited (and also endangered) to coastal regions by the time Danish explorer Vitus Bering arrived with his team.


Published on July 1st 2015 by under Mammals.
Article was last reviewed on 16th September 2019.

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