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Fun Facts About Manatees

A manatee munching down on some sargassum.
A manatee munching down on some sargassum.
Credit: USGS - Sirenia Project

Kingdom: Animalia

Phylum: Chordata

Class:  Mammalia

Order: Sirenia

Family: Trichechidae

Genus: Trichechus

Species: Trichechus manatus(West Indian manatee), Trichechus inunguis (Amazonian or South American manatee), Trichechus senegalensis (West African manatee)

Subspecies:T. manatus manatus (Antillean manatee), T. manatus latirostris (Florida manatee)

 

Basic manatee facts:

Manatees are part of the order Sirenia, something they share with an animal in the eastern hemisphere called a dugong.

Manatees are thought to have evolved from four-legged land mammals over 60 million years ago.

Even though they live in the water, manatees are more closely related to elephants and hyraxes than sea lions and whales.

They never leave the water, but like all marine mammals they have to come to the surface to breathe air. A resting manatee can hold its breath for up to 15 minutes, but when it's swimming, it must surface every 3 or 4 minutes.

Manatees measure up to 13 feet (4 meters) long, and weigh as much as 1,300 pounds (590 kilograms).

They have paddle-like flippers with a fingernail on the end — a remnant of evolution, when they lived on land.

Manatees swim at about 3 to 5 mph (5 to 8 kph), but have been clocked swimming for short bursts at 19 mph (30 kph).  They are agile swimmers that can somersault, roll and swim upside down.

Manatees emit a wide range of sounds used in communication, especially between cows and their calves. Adults communicate to maintain contact and during sexual and play behaviors. Taste and smell, in addition to sight, sound and touch, may also be forms of communication for manatees.

Manatees are the only surviving marine mammals that eat only plants. Each one of the massive sea cows can eat upwards of 100 pounds (45 kg) of vegetation daily — about a tenth of their body weight — due to the low nutritional value of the plant life.

A thick bristly upper lip helps them gather food. The animals use the lip to grasp vegetation, as it is split down the center, and each half can be moved independently.

Manatees can live up to 60 years.

Manatee pregnancies last for 11 to 13 months. Newborns weigh about 60 pounds (27 kg). Mothers must take their newborns to the water's surface for their first breath, but calves can swim on their own after an hour or so.

Calves are dependent on their mothers for two years.

They cannot survive temperatures below 60 degrees Fahrenheit  (15.5 degrees Celsius). Their natural source for warmth during winter is warm, spring-fed rivers.

They may occasionally be disturbed by crocodiles, and suffer from habitat-degradation, but their only significant predator is humans.

 

Where manatees live:

Manatees inhabit the shallow, marshy, coastal areas and rivers of the Caribbean Sea, the Gulf of Mexico, the Amazon Basin and West Africa.

Wherever they live, manatees enjoy warmer waters and are known to congregate in shallow waters. They frequently migrate through brackish water estuaries to freshwater springs.

 

Conservation Status: Vulnerable

Manatees are vulnerable because the number of mature individuals is currently estimated to number less than 10,000 (2,500 are those left in the United States) and is expected to decline at a rate of at least 10 percent over the course of three generations.

One reason for the vulnerable status is that manatees reproduce very slowly — the time between generations is about 20 years. In addition, fishermen trawling with nets in the Amazon and West Africa pose a grave threat to these slow-moving mammals.

Habitat loss from waterfront development also impacts their survival. Manatees are also vulnerable to collisions with speed boats.

Manatees are also a federally listed endangered species in the United States.

 

Odd manatee facts:

The name manatee comes from the Taíno (a pre-Columbian people of the Caribbean) word manatí, meaning "breast."

Their eyes are small, but their eyesight is good. Manatees have a special membrane that can be drawn across the eyeball for protection. Their hearing is good too, despite not having outer ear structures, because manatees have large inner ear bones.

Manatees spend most of their time feeding, resting or travelling.

In spite of their size, manatees have relatively little fat; they are a sub-tropical species very susceptible to cold.

Manatees' only teeth are called marching molars. Throughout a manatee's life, the molars are constantly replaced, an adaption to their diet of abrasive vegetation.

Manatees have only six neck vertebrae. Most other mammals, including giraffes, have seven. As a result, manatees cannot turn their heads sideways, and must turn their whole body around to look behind them.

They have pelvic bones that aren't attached to their skeletal frames that are an evolutionary remnant of when their ancestors lived on land.

 

More info:

IUCN Red List: West Indian Manatee

IUCN Red List: West African Manatee

IUCN Red List: Amazonian Manatee

USGS Sirenia Project

National Geographic – Manatees

Florida Fish and Wildlife Conservation Commission – Florida Manatee Program

Save the Manatee

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