The Steller’s sea cow was a large marine mammal that was part of a group of animals called sea cows. Unfortunately, due to human factors, such as hunting, it was driven to extinction in the 18th century. It is believed that the last Steller’s sea cow was wiped out around 1768.

The Hydrodamalis gigas were native to the islands in the Bering Sea and around shallow waters in the Bering Sea region. Due to its environment was able to grow to an immense size. They were given their name by the man who discovered them in 1741, German Zoologist Georg Wilhelm Steller. Let’s take a look at this remarkable creature.


It has a distinctive Sirenian trunk-like snout
It has a distinctive Sirenian trunk-like snout

The Stellar’s sea cow had a unique appearance in relation to the existing members of the Sirenians, such as manatees and dugongs. They were far larger than modern-day sea cows, as they could reach lengths of up to 9 meters or 30 feet. In comparison, a manatee can only get to a third of that size at 9-10 feet.

It is estimated that the animal weighed anywhere between 8-10 tons, which gave it the title of one of the largest mammals, other than whales, to grace the Holocene epoch.

It is typical for sea cows to have a large trunk-like snout that is directed downwards. This helps them to graze on the sea floor successfully. The Stellar’s sea cow was very similar in this respect.

It was three times larger than a modern-day manatee
It was three times larger than a modern-day manatee

Another key feature of the sirenians is their dental layout. Normally, they have molars in their mouth to process the large quantity of kelp, seaweed, sea grass, and other plant material that they consume daily. However, the Steller’s sea cow breaks this trend by actually using robust bristles on its upper lip to rip through seaweed. Remarkably, they don’t actually possess any teeth. Instead, they use a pair of plates, named ceratodontes, which are located on the creature’s palate and mandible.

Another key difference between Stellar’s sea cow and its contemporaries is its positive buoyancy state. Unlike other sea cows, it actually can not completely submerge itself below the water.


Although the information detailing the complete natural history of the Steller’s sea cow is low due to its quick extinction after discovery, they were believed to be native to the Bering Sea region. This region in the North Pacific Ocean sits between North America and Russia. More specifically, they inhabited the shallow waters around the Commander Islands and the Aleutian Islands.

They were believed to inhabit kelp forests, as they spent most of the day feeding. Interestingly, they only were required to lift their head every 4-5 minutes so that they could consume a large quantity of plant matter.


The Steller’s sea cow, like its relatives, was a herbivore and targeted seagrass, kelp, and seaweed. Out of these food sources, kelp made up the bulk of their diet, as the availability of seagrass could not sustain a thriving population that required a significant quantity of food per day.

Their immense size required a large quantity of kelp consumption
Their immense size required a large quantity of kelp consumption

It is said that during hard times and periods of kelp forest decline, the steller’s sea cow would actually fast and adapt to the availability of kelp in their ecosystem.


Similarly to manatees, the Steller’s sea cow was a very social animal and would operate in family units. These groups would help one another and support injured members.

They were monogamous creatures, meaning that they would mate with one partner only and raise the young together. The female sea cow was only capable of having one child at one time due to her single set of mammary glands, and it would take around one year from conception to birth.


Threats are around the corner for many creatures in the animal kingdom. Due to how the existence of the Stellar’s sea cow played out, it is safe to assume that mankind was arguably its biggest threat during its time on earth. Hunters would kill them for their abundance of blubber. With an already small population, around 2000 individuals, upon their discovery, they did not stand a chance of population growth.

Steller's sea cow was hunted to extinction in the 18th century
Steller’s sea cow was hunted to extinction in the 18th century

In terms of other animal predators, due to its incredible size, it is only killer whales or orcas and sharks that could take down the Steller’s sea cow. However, due to its positive buoyancy, it would have been hard for orcas to drag them below the water’s surface. It is also believed that the nature of the kelp forests prevented large sharks from hunting them.

Facts about the Steller’s sea cow

  1. They are monogamous animals, meaning they have one mate
  2. Humans hunted the Steller’s sea cow to extinction in the 18th century
  3. They were found in the Bering Sea in the North Pacific
  4. Their main predators are Orcas
  5. They can reach up to a staggering 30 feet in length


Are Steller’s sea cows still alive?

No, Steller’s sea cows are officially extinct. There was a population in the Bering Sea many years ago. However, they have not been seen for centuries.

When was the last Steller’s sea cow killed?

It is believed that the last Stellar’s sea cow was killed around 1768. This took place in the Bering Sea, where their last population was located.

Why did the Steller’s sea cow go extinct?

The Steller’s sea cow went extinct due to being hunted by fishermen and native tribes in the North Pacific. By the time they had been officially discovered, there were only around 2000 individuals left in the wild.

Where did Steller’s sea cows live?

The Steller’s sea cow occupied the North Pacific Ocean, and in particular, the Bering Sea. Their populations were mostly confined to some Bering Islands, such as the Commander Islands and the Aleutian Islands.

What did the Steller’s sea cow eat?

The Steller’s sea cow had a very refined and somewhat limited diet. They mainly consumed kelp, which was abundant in their habitat. They would also eat seagrass when they could.

About Ocean Info

At Ocean Info, we dive deep into ocean-related topics such as sealife, exploration of the sea, rivers, areas of geographical importance, sailing, and more.

We achieve this by having the best team create content - this ranges from marine experts, trained scuba divers, marine-related enthusiasts, and more.

Sea Anemone with Clownfish

Dive into more, the ocean is more than just a surface view

Bottlenose dolphins are known to help stranded humans back to the shore

8 of the Most Intelligent Marine Animals

From dolphins' awe-inspiring communication skills to orcas' social complexity, the ocean is home to some of the most intelligent marine animals.

Share to...