Mammals Active day and night

Steller's Sea Cow

Hydrodamalis gigas

iNaturalist Wikipedia

The Steller's Sea Cow was a gentle, 10-ton titan of the North Pacific that lived in the heart of the world's most kelp-rich waters. Though it vanished just 27 years after its discovery, it remains one of the most fascinating examples of megafauna to have ever graced our coastlines.

0 Sightings

0 Habitats

Quick Identification

straighten

Size

Length of 8–9 metres (26–30 feet); weight estimated between 8–10 metric tons (17,600–22,000 lbs)

palette

Colors

Dark brown to blackish skin, often described as resembling the bark of an old tree; occasionally featured light patches or white streaks from scarring

visibility

Key Features

Massive spindle-shaped body with a relatively small head
Thick, craggy, bark-like skin used for protection against ice and rocks
Forked tail fluke similar to that of a whale or dolphin
Short, stump-like forelimbs used for walking along the sea floor

When You’ll See Them

schedule

Activity pattern Active day and night

brightness_5

Peak hours Continuous activity throughout the day and night

calendar_month

Season Year-round

restaurant

Diet Obligate herbivore specializing in large brown kelp and other seaweeds; used keratinous grinding plates instead of teeth.

park

Habitat Shallow, sub-arctic coastal waters and rocky shorelines with high kelp density.

Behavior

The Steller's Sea Cow was a remarkably docile and slow-moving marine giant. It spent the majority of its life floating at the ocean's surface in shallow water, as its massive size and high buoyancy made it unable to fully submerge. They were highly social creatures, often found in large family groups or herds. Observers noted that they exhibited strong emotional bonds; when a member of the herd was injured, others would crowd around it in a protective circle, an altruistic behavior that unfortunately made them easier for hunters to target.

These sirenians were constant grazers, moving slowly through kelp forests and using their powerful, toothless mouths to tear at marine vegetation. They were known to be very tame and showed little fear of humans or boats. Because they lacked the ability to dive, they were frequently seen with their backs exposed above the water, appearing like dark, floating islands to early explorers. They were also observed to be monogamous, with pairs often staying close together regardless of the herd's movement.

photo_camera EverydayEarth exclusive

Camera Tips

To capture a creature of this scale in its historical habitat, your camera placement would need to be strategically positioned along the rocky intertidal zones where kelp is most abundant. Because the Steller's Sea Cow could not submerge, a shore-mounted camera on a high tripod or a cliff-edge looking down at a 45-degree angle would be ideal. This perspective ensures you capture the massive, 30-foot profile of the animal without the distortion of the water's surface, particularly during low tide when they would congregate in the shallowest channels to feed.

For those using AI-powered triggers, you would need to set a wide detection zone. A sea cow's movement is slow and rhythmic, so a standard motion sensor might mistake it for a floating log. Using a camera with time-lapse capabilities set to 30-second intervals is a safer bet to document their grazing patterns. Since they inhabited the frigid Bering Sea, high-quality infrared (IR) sensors are mandatory to penetrate the frequent heavy fogs and maritime mist that would otherwise obscure the lens during their active night-time feeding sessions.

Baiting would involve finding a sheltered cove where giant kelp (Nereocystis) naturally drifts and accumulates. Steller noted that these animals were particularly fond of freshwater; placing your camera gear near a river mouth or a spot where freshwater streams flow into the sea would significantly increase your chances of a close-up encounter. The animals often gathered in these areas to rest or drink, providing a predictable location for consistent monitoring. Ensure your equipment is housed in a rugged, waterproof, and salt-resistant casing to withstand the harsh, corrosive sub-arctic environment.

Similar Species

Species that look similar or are commonly confused with Steller's Sea Cow.

Dugong

The Dugong also has a forked tail but is much smaller, lives in tropical waters, and is capable of fully submerging.

West Indian Manatee

Manatees have a rounded, paddle-like tail fluke and possess fingernails on their flippers, which the Steller's Sea Cow lacked.

Browse all Mammals arrow_forward

Frequently Asked Questions

Steller's Sea Cows were active day and night. They were continuous grazers that spent almost all their waking hours eating kelp to maintain their massive body fat in the freezing sub-arctic waters.

Unfortunately, Steller's Sea Cows have been extinct since 1768. Historically, they could only be found in the remote Commander Islands of the Bering Sea, so they would never have appeared in a typical backyard setting.

They were strict herbivores that fed on various types of kelp and seaweed. They were unique among sirenians because they lacked teeth entirely, using two hard, white bony plates to grind up tough marine plants.

No, they were never found near suburban areas. They were specialized for the remote, icy, and rocky coastlines of the North Pacific and were driven to extinction long before modern suburbs existed.

Size is the most obvious difference; Steller's Sea Cows were up to 30 feet long, nearly three times the size of a manatee. They also had a forked, whale-like tail fluke, whereas manatees have a rounded, paddle-shaped tail.

Record Steller's Sea Cow at your habitat

Connect a camera to start building your own species record — AI identifies every visitor automatically.

Join free Identify a photo