Sea Cow

Sea cows are a group of aquatic mammals that contain different species, such as the Dugong and Manatee. This group of marine mammals is known as Sirenia or Sirenians. Interestingly, they were actually named after ‘Sirens’ as they were discovered by sailors that mistook them for mermaids.

Sirenians had a common ancestor with elephants, but their lineage deviated around 50 million years ago, and the Sirenian evolution began. Over time, some sea cow species have gone extinct, only leaving the two main living species with a number of variants.

Appearance

Sea cows have a distinctive look, with a long trunk-like snout and wide bodies. Their sizes range from 2.5 – 4 meters, or 8.2 – 13.1 feet, in length, and they can reach weights of up to 1,500 kg or 3,300 pounds.

The sea cow has very dense bones that help it balance itself in the water. As the sea cow typically has a large amount of blubber, it can become extremely buoyant. The heavy bones are able to fight against this and keep them stable.

As the sea cow is such a large creature, it has developed a cigar-shaped body to help it move easier through the water. The trunk-like mouth allows them to consume vast quantities of seaweed and seagrass to sustain their herbivore diet.

Credit: NOAA National Ocean Service

The color of a sea cow can change depending on how much algae begins to form on its thick skin. This can sometimes make it hard for boats to see them, but also can hide them from potential predators.

Unsurprisingly, the size of the sea cow does limit its speed underwater. It normally travels at speeds of around 5 miles per hour but has been known to reach 15 miles per hour for short periods.

The snout is vital to sea cows as they utilize it to gather food. The whiskers outside their mouths allow them to navigate their environment more efficiently.

Habitat

Although sea cow species generally look for similar criteria when choosing their habitat, each species varies slightly in terms of its location.

The West Indian manatee, or North American manatee, like its namesake, occupies an area around the Caribbean, North America, and even parts of South America. Florida is a common area to spot the creature. Similarly to its relatives, it mostly operates in shallow waters.

Manatees are incredibly adaptable when it comes to water types. They can live in salt and freshwater due to their ability to regulate variations in salinity. This allows them to venture into coastal areas and rivers. However, due to their warm-blooded nature, they tend to stick to warm waters.

The African manatee is the epitome of the sea cow’s habitat adaptability. It is found in coastal regions, inland rivers, and rainforest waters. They can be found in an incredible 21 different countries across Africa.

The Amazonian manatee strays from the typical path of a Sirenian, as it is the only sea cow to solely inhabit freshwater environments. It is found in South America’s Amazon region, in Brazil, Peru, Columbia, and Ecuador.

The dugong is the final living sea cow species, which inhabits the Indo-West Pacific region, and is the only Sirenian to cover this area. Like other sea cow species, the dugong looks for shallows rather than the open ocean.

The Steller’s sea cow, or Hydrodamalis gigas, was native to the North Pacific and occupied areas in the Bering Sea. Unfortunately, the steller’s sea cow, named by Georg Wilhelm Steller in 1741, was driven to extinction in 1768. The majority of them lived around the Commander Islands, which is a Bering island located between Russia and Alaska. Unfortunately, they went extinct, and with it, the sea cow influence was lost in the area.

Diet

All sea cow species are herbivores. All sea cow species feed on sea grass, seaweed, and kelp, on the ocean floor. They eat large quantities of these plants to sustain their mass.

Credit: Ruth Hartnup (CC BY 2.0)

Their strong mouths, and in particular their upper lips, contributes to their ability to scan the sea floor with ease and extract plants. They then utilize their molariform teeth to break down the vegetation.

Reproduction

Sea cows are gonochoric, meaning that each sex has its own reproductive organs. In order to find a mate, sea cows have the ability to vocalize and ‘bark’ to communicate. This helps them to form herds during mating periods.

Sea cow species, such as the dugong, have a gestation period of 13 months. Similarly to many mammals, there is a significant time spent raising the calf. Only when the calf is old enough to forage and reproduce can it go and live a solitary life.

Threats

Many sea cow species do not have natural predators in their habitat due to their size and the habitats they inhabit, such as shallow rivers and coastal areas. There have been a handful of reports of sharks and alligators attacking sea cows, but it is not a regular occurrence.

In the past, sea cows have been targets for hunters. The Steller’s sea cow, which weighed a staggering 8 – 10 tons, was driven to extinction in 1768, shortly after they were discovered.

Credit: Biodiversity Heritage Library (CC BY 2.0)

Sea cows around the world have always had to contend with the rise of the fishing industry. There is always a risk of propellers and motors hitting them in shallow waters.

Facts about the Sea Cow

1. There are four living species of sea cows in the world.
2. The extinct stellar’s sea cow was the largest Sirenia species in history.
3. As mammals, sea cows can only raise one child per reproductive cycle.
4. They are herbivores and seek out vegetation on the sea floor.

FAQs