Sea Cow vs. Manatee

Below, readers can explore facts about the Steller’s sea cow and the manatee. The sea cow and manatee are both large marine animals with small heads whose main food source is seagrass. Although there are a few differences between the two species, many facts of their lives are the same. 

Left Image Credit: Wikimedia Commons
Right Image Credit: US Fish and Wildlife Service (CC BY 2.0)

Main Differences Between a Sea Cow and a Manatee

Here are the top five main differences between the sea cow and the manatee: 

• Appearance: Both the sea cow and manatee have similar appearances, with a thick blubber skin, small head to body ratio, and a large dorsal singular fin.
• Size: Sea cow can grow up to 9 metres, similar in size to manatees.
• Habitat: Sea cow live in shallow waters, like manatees do.
• Diet: The diet of Sea cows is predominantly sea grass, whereas manatees are more broad and eat a range of freshwater and saltwater plants.
• Buoyancy: Sea cows are naturally buoyant, making it difficult for them to dive down, unlike the manatee. 

We’ll explore these differences and interesting facts about marine animals more below.

Sea Cow

What is a Sea Cow? 

The Steller’s sea cow was one of two members of the Dugongidae family. It was a large animal found around the Commander Islands in the Bering Sea. It was first described, by its namesake Georg Wilhelm Steller, in On the Beasts of the Sea, in 1741. 

Is the Sea Cow Extinct? 

Yes, the Steller’s sea cow is extinct. It went extinct in the 18th century. The animal was hunted to extinction only a few years after it was officially discovered, as demands for its fat and meat were incredibly high.

Sea Cow Appearance 

The sea cow was a large animal, reaching up to thirty feet or nine meters. One skeleton discovered in 1987 was much smaller, only around ten feet in length. Other complete skeletons range from seventeen up to twenty or more feet. The animal had a downward-turned snout, like manatees and dugongs, in order to make eating grass off the seafloor easier.

The Steller sea cow had a very thick outer skin, around 1 inch; this protected it from sharp rocks and ice that might be on the seafloor or above it as it searched for food. The sea cow also had very thick blubber, around three to four inches. This allowed it to survive in the freezing cold waters to which it was native.

They were brownish-black in color, with some individuals sporting white patches. The skin had a rough texture, something that scientists now believe was caused by parasites delving into the skin and creating depressions. 

The sea cow had a small head compared to its body, something dugongs and manatees still exhibits to this day. They also had large upper lips that extended past the lower jaw.

Where did Sea Cows Live? 

At the time of its discovery, the sea cow was living in the shallow areas around the Commander Islands (including the Bering and Cooper Islands) in the Bering Sea. Earlier fossils were discovered around Monterey Bay, California, and along Honshu, Japan. 

Reproductive Habits 

When writing about sea cows, Steller observed that females had one set of mammary glands. This led him to the conclusion that these creatures only gave birth to one calf a year. Mating was supposed to take place in early spring. Unfortunately, due to the fact that these creatures went extinct in the 18th century, less is known about their mating habits. 

What Did Sea Cows Eat? 

Like manatees and dugongs, the sea cow fed on seagrasses. The Steller’s sea cow was also toothless. This is an attribute that manatees and dugongs do not share. Instead of teeth, the sea cow had interlacing bristles that it used to tear at grass.

Interestingly, the sea cow was positively buoyant. This means that it was unable to submerge itself completely. This sets it apart from other sirenians like the dugong and the manatee.

Sea Cow Facts

• The sea cow fed on seagrasses.
• The sea cow went extinct in the 18th century.
• It didn’t have teeth.
• Steller posited that the animal produced one calf per year.
• The sea cow had a small head in comparison to its body.

Manatee

What is a Manatee? 

Manatees are large herbivores that are sometimes known as sea cows but are, in fact, a different species. There are three species of manatee making up three of the four living species of the order Sirenia, the fourth being the dugong. The three species of manatee are: 

• Amazonian manatee or (Trichechus inunguis)
• West Indian manatee or (Trichechus manatus)
• West African manatee or (Trichechus senegalensis)
  

Throughout history, manatees have been linked to mermaid folklore. In some cultures, such as in West Africa, they have been considered sacred and even thought to once be human.

Manatee Appearance 

Like the sea cow, these are large animals. They grow to similar lengths, around thirteen feet long but weigh up to 1,300 pounds. Manatees also have paddle-like flippers, similar to those that dugongs and sea cows use. The manatee’s tail is the clearest difference in appearance. It is paddle-shaped, while the sea cow’s tail is fluked like a whale’s (or a dugong’s).

Interestingly, the manatee has unique cervical vertebrae. It has only six, whereas all other mammals have seven. That is, except for two types of sloths. Manatees also have teeth, whereas sea cows have white bristles.

Where Do Manatees Live? 

They also prefer to live in shallow, coastal areas, but their distribution is more widespread than the sea cow. For example, they are known to live around the Amazon basin, the Gulf of Mexico, and West Africa. The three species of manatee are primarily distinguished by where they live, for example, in the Amazon basin or along the coast of West Africa. Manatees are also a migratory species. In the United States, they live around the coast of Florida in winter.

Reproductive Habits 

When manatees are born, they weigh around 66 pounds or 30 kg each. They breed once every two years, and a single calf is born, like the dugong and sea cow. Manatees become sexually mature around five years of age.  If a manatee loses a calf, they may experience an interval of two years before another is born. 

What Do Manatees Eat? 

Like Steller’s sea cow, manatees are herbivores. They eat around 60 different freshwater and saltwater plants. They have also been known to eat fish from nuts. Some examples of plants that they enjoy include turtle grass, sea clover, marine algae, and shoal grass.

Facts about Manatees

• Manatees are threatened by vessel strikes and sound pollution.
• Manatees are herbivores.
• When manatees are born, they weigh around 66 pounds.
• Throughout history, manatees have been linked to mermaid folklore.
• They prefer to live in shallow, coastal areas.

Threats to Sea Cows and Manatees

Unfortunately, the sea cow went extinct due to overhunting in the 18th century. Therefore, threats to their continued survival cannot be analyzed. But, the threats to manatees are very real. They are threatened by human encroachment on important habitats, pollution, and climate change. Predators, like crocodiles, threaten both the manatee (and dugong) young. 

Manatees are slow-moving creatures. This means that they are threatened by vessel strikes. The latter is one of the leading causes of death or injury to these large creatures. 

Many manatees exhibit scars from encounters with vessels, such as propeller-driven boats and ships. If the initial collision does not take the manatee’s life, the resulting infection may. Many ships also emit low frequencies that confuse manatees. This has been posited as a reason why so many of these large creatures have collided with vessels.

Today, the dugong is the only remaining member of the Dugongidae family, the other being the Steller’s sea cow. It is considered threaded by the IUCN but is protected throughout its entire range.

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