Steller’s Sea Cow

Steller’s Sea Cow
Domain: Eukarya
Kingdom: Animalia
Phylum: Chordata
Class: Mammalia
Order: Sirenia
Family: Dugongidae
Genus: Hydrodamalis
Species: H. gigas

An older cousin of today’s dugong, the Steller’s sea cow, is an extinct marine mammal that was found in the cold waters of the Bering Sea. The story of Steller’s sea cow is not a happy one, and it may make you feel conflicted. However, it is a tale that must be told because it has had a major impact on modern extinction.

Hydrodamalis gigas was a giant mammal that survived the last Ice Age over 14,000 years ago, and it persisted through the Quaternary extinction, which was a major extinction event that may have been caused by a mixture of increased human activity and natural climate change. This gentle giant was adapted to survive much colder waters than the habitats favored by its smaller, younger cousins the manatees and dugongs.

These cold-water behemoths were first discovered, named, and documented by the German naturalist Georg Steller in 1741, and they were estimated to have a population of about 2,000. He described them to be large, slow-moving mammals that seemed to float near the surface because they lacked the ability to submerge themselves. This may be false, we’ll never know, but their surviving cousins can submerge themselves. Steller’s sea cow had no real teeth; instead, they used horny plates in their mouths to crush kelp and seaweed.

Soon the sea cows were hunted for their meat, hide, and blubber. Steller reported that the meat was delicious and far better than the sea otters they’d hunted, and he claimed that a single sea cow could feed several people for a month. The sea cow possessed no defenses against the hunters, other than that their hide was thick enough to defend against most harpooning.

Steller also recorded that they were incredibly loyal to others of their herd, trying to help those who were caught and going so far as to visit the beaches where their dead lay. Now, keep in mind this is all from the written record by Georg Steller and may not be entirely accurate, at least in terms of the animal’s behavior towards each other.

Sadly, we’ll never know exactly what these gentle sea cows were like because they were hunted to extinction by 1768—less than 30 years after their discovery.

When I first leaned about the fate of the Hydrodamalis gigas, I was honestly disgusted with my own species. Those people were aware of the low numbers and weaknesses of these harmless creatures and still hunted them unsustainably for their meat and blubber. The previous extinction event might have dwindled their numbers beyond recovery, but humans finished them off.

But the extinction of the sea cows allowed the scientists of the time to observe and understand modern extinction, because they had either believed the dodo to still be alive or not real to begin with (the dodo’s last widely accepted sighting was reported in 1662, a hundred years before Stellar and his fellows). However, the existence and the extinction of the sea cows were recorded well enough to prove they were real before they were gone.

While a sad tale, the story of Steller’s sea cows was needed for us to understand extinction beyond what we could gather from fossils and geological data.

Sources and cool links to check out:
Ocean: The Definitive Visual Guide made by the American Museum of Natural History