Article

Manatees

By Dan Odell, Ellen Dierenfeld, Sally Mizroch, Will Waddell
  • Grades: 1–2, 3–5, 6–8, 9–12

The following questions were answered by whale biologist Sally Mizroch, research biologist Dan Odell, zoo nutritionist Ellen Dierenfeld and zoo biologist Will Waddell.


How many manatees are there in the world? Where are they found?
There are about 1,500 manatees in the United States, almost all in Florida. No one knows how many there are in the rest of the world, because it is very difficult and expensive to count them. They are found throughout the West Indies, along the east coasts of Central America and South America, throughout the Amazon River basin, along the coast of West Africa, and in the Congo River and other large rivers of Africa that flow into the Atlantic Ocean. Although populations have been much reduced in most areas, there are probably still many thousands.

How long can manatees live?
They can probably live to be at least 50 years old. There is a manatee named "Snooty" in Bradenton, Florida, who is in his late forties. He was born in an aquarium in Miami in the late 1940s.

What do manatees eat?
In an aquarium, manatees are fed mostly romaine lettuce, which is similar in composition to the plants they consume in the ocean. In fact, manatees are unique in being the true herbivores of the marine mammals. We've looked at vitamin E in blood samples from manatees, and they duplicate cows, while all other marine mammals (whales, seals, dolphins, otters) duplicate land carnivores in vitamin E concentrations.

How many babies do manatees have at a time?
Manatees usually have only one baby (called a calf) at a time. Twins are rare but they do happen.

How big are manatees? How big are baby manatees compared with adults?
The "average" adult manatee is about ten feet (three meters) long and weighs over 1,000 pounds (about 300 kilograms). The "average" calf is about four feet (120 centimeters) long and weighs about 60 pounds (30 kilograms).

What is the largest manatee on record?
The longest one on record is just over four meters long. The heaviest one weighed 3,500 pounds.

How long have manatees been on earth?
The ancestors of manatees are about 50 million years old.

Why are manatees so friendly?
Not all of them are friendly! Some avoid people. In other cases, people feed manatees (which is against the law) and the manatees will then approach people expecting to be fed, so they only appear to be friendly.

How do you catch manatees to study them?
The best way to catch them is with a big net, which works very well. Manatees cannot be captured by being shot with a tranquilizer underwater. They would stop breathing and drown.

What is being done to save the manatee?
Manatees are protected by a variety of laws in all the countries in which they occur. In the U.S. they are protected by the Marine Mammal Protection Act, the Endangered Species Act and the Florida Manatee sanctuary act. Unfortunately, laws in many places are difficult to enforce and some, like the West Indian manatee, is still an endangered species.

The West Indian manatee is composed of two subspecies — the Antillean manatee (found from Cuba and Mexico to Brazil) and the Florida manatee (found primarily in Florida but ranges from Texas to Rhode Island). West Indian manatees are kept in a number of zoos and aquariums around the world. Antillean manatees have been held in several facilities in Europe, Central and South America, Japan, and China. At the present time, Florida manatees are only held in the state of Florida. The U.S. government has established regulations for keeping marine mammals (including manatees) in captivity. These regulations cover pool size, water and food quality, water temperature, and so on. In Florida, almost all of the manatees in captivity were rescued and are in rehabilitation programs (like the one operated by Sea World of Florida). The objective of the rehabilitation programs is to return the manatees to their natural habitat as soon as they are certified healthy by the veterinarians. However, some manatees have been so severely injured that they could not survive in the wild and will probably not be released.

  • Subjects:
    Animal Behavior and Structure, Fish and Marine Life
  • Skills:
    Science
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