The ‘Sea Cows’ of the Coasts

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Manatees, also known as “sea cows,” are large, aquatic and herbivorous mammals. They are adept swimmers that spend their days cruising through the seas and grazing on the fields of grass that grow underwater. Each day, they spend up to eight hours feeding on vegetation, consuming 5-10 percent of their body weight in vegetation daily. While they may occasionally eat the fish, clams and small invertebrates residing in underwater plants, manatees feed predominantly on sea grasses, water weeds and other aquatic vegetation.

Unique families of mammals

Sea cows belong to a unique group of mammals called the Sirenia — named after the mermaids of Greek mythology, which were known as sirens. In fact, the term “sea cow” originally referred to the now extinct Steller’s sea cow (Hydrodamalis gigas), the largest known member of Sirenia that inhabited the subarctic Bering Sea. Today, the term applies to surviving Sirenians, namely the dugongs and the manatees.

The existing species of the Sirenia fall into two distinct families, Dugongidae and Trichechidae, and have four extant species. The Family Trichechidae includes three species: the Amazonian manatee (Trichechus inunguis), the West Indian manatee (Trichechus manatus), and the West African manatee (Trichechus senegalensis). Dugongidae has only one extant member, the dugongs.

Distinctive appearance

All sea cows are torpedo shaped animals with long, broad backs that taper to paddle-like, dorso-ventrally flattened tails. Their gray-brown skin is smooth in some species, but wrinkled in others. Adults are between 9 and 12 feet long and weigh between 250 and 1000 pounds. Female sea cows are heavier than males.

Manatee species have large round bodies, downturned snouts, short rounded paddle-like flippers, and a horizontal tail fluke that they use to move around. In contrast, the dugongs are more streamlined, lack nails on their flippers, and have a bi-lobed tail. However, all the sea cows have two flippers, which have 3-4 nails on the second, third and fourth digits in manatees, but have no nails in dugongs.

Warm aquatic habitat

Sea cows reside in shallow waters along coastal, marine habitats and inlets, except for the Amazonian manatees that strictly inhabit freshwater habitats in the Amazonian Basin. In the colder months, the sea giants prefer warm, freshwater springs and warm water areas near power plants. But in the warmer months, they move to tepid saline waters.

When water becomes very cold, it can be fatal for the sea cows as most of them lack the means to regulate their body temperature. In fact, one of the largest mortality factors for sea cows is exposure to cold water. So the animals reside in waters that are above a certain temperature in order to survive.

For instance, West Indian manatees migrate to warmer areas when the water temperature falls below 20 degrees Celsius (68 degrees Fahrenheit), African manatees prefer temperatures above 18 degrees Celsius (64 degree Fahrenheit), while Amazonian manatees prefer higher temperatures above 25-30 degrees Celsius (77-86 degrees Fahrenheit). The dugongs tolerate temperatures not lower than 19 degrees Celsius (66 degree Fahrenheit).


Sea cows are polygamous animals. When a cow undergoes estrus, she attracts herds of males who follow her while she swims to evade them. Females use this evasive swimming behavior to select a superior mate.

Males who happen upon others engaging in sexual behavior are often encouraged to participate. These groups of male may remain near a single female for several weeks before a successful copulation. During this period, males and females often grasp each other with their flippers.

For sea cows, the gestation period lasts 12 to 14 months, and eventually, the cows travel into shallow waters to give birth. Most females give birth to one calf, although some births result in twins. The calves are born with teeth and begin foraging in their third month, and they generally continue nursing for about 18 months to four years.

Very young calves synchronize all activities, such as breathing and resting, to match their mother. The young calves cling to their mother and ride on her back. The calves grow and attain sexual maturity in 3-10 years, and then reproduce every 2 to 7 years, though a cow may breed more frequently if it loses a very young calf.


Sea cows are active throughout the day. When accelerating, they bring their flippers up against their body, but at cruising speed the flippers typically hang down—the flippers are used to aid in turning and stopping. Though sea cows can achieve higher speeds of up to 15 miles per hour when being pursued, they often move about 2-6 miles per hour.

These giant mammals have sensory hairs all over their bodies and on their rostrum, and a touch-sensitive epidermis. When they sense danger, they display agitated behavior and often make impulsive chirping sounds. Groups of Sirenians may even stand against and head-butt predators, but more typically, they attempt to flee danger.

Sirenians communicate by sound, especially between mother and calf. Actually, cows and calves use vocalizations to keep track of one another. While their visual capabilities are comparable to humans, the visual field of their eyes overlap so they blink often to keep their eyes lubricated.

Have an amazing time with the sea cows!

Want to spend a wonderful day swimming with manatees? At Captain Mike’s, we offer manatee tours in Crystal River, Florida—the only place in North America where you can legally swim with the manatees.

With the water temperature in Crystal River springs being a consistent 72 degrees throughout the year, more than 400 manatees migrate to Crystal River each year to escape the cold waters of the Gulf of Mexico. There are also numerous manatees residing in the springs through the summer months. So with hundreds of manatees, Crystal River, Florida, is a perfect spot for you to get up close and personal with the sea cows.

During your tour, you will dive into the water and swim near manatees and, because they are curious and gentle animals, they will approach you for a close and exhilarating encounter. But you can also view the sea cows from a pontoon boat if you would rather not get wet. Whichever option you choose, your manatee tour will be a delightful, fun activity.

At Captain Mike’s, we have manatee tours designed for people of all ages, and an experienced captain will help you stay within the mandated guidelines. Join us for a manatee tour in Crystal River and learn about manatees and their habitats. For more information, visit Captain Mike’s Swimming with the Manatees website.

Swimming with the Manatees boasts the best water adventure in Crystal River, Florida with lots of things to do for you and your family. For more information, contact us online, or call us at (352) 571-1888.

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