Manatees are slow - moving marine mammals with large paddle shaped tails. Typically, females, called cows, are larger than males or bulls, and can weigh up to 3,500 pounds. Gestation for a female manatee is between twelve and fourteen months and they generally give birth to one calf at a time. The average size of a manatee is closer to 1200 pounds and up to twelve feet in length.
Manatees have a well developed sense of hearing, more in tune to higher frequencies. Studies to date indicate that manatees are near-sighted, considering that manatees frequent areas with turbid water, hearing would be a more valuable asset.
The mouth of a manatee, referred to as the oral disk, is like a shorter version of an elephant’s trunk-prehensile. The muscles in their face allow them to manipulate food into their mouth. They have between six and eight teeth in the four corners of their mouth in the back area only, known as “marching molars”. When a tooth closest to the front wears out, it is replaced by the tooth behind it, so manatees always have a full set of teeth. Vibrissae are the bristle-like hairs you see on their oral disk. They work like “feelers” and help the manatee explore and discern edible material. They also help pull the food inside their mouth.
Manatees have thick skin, but unlike blubber, it does not protect them from very cold water. Their lungs run the length of their body and function independently allowing them to control their buoyancy. Dense ribs, lacking marrow, help them rest easily on the bottom.
Fossils from sirenians have been found around the world, but Florida and the Caribbean are the only areas known to have examples from every era dating 50 million years ago to the present.
Over 35 species of sirenians have been known to exist, but only four species in two families exist today. Three of those species are manatees, the fourth in the dugong family. The Amazonian Manatee is strictly freshwater, smaller and faster than the other two species. The West African is somewhat larger than the Amazonian, but has a lifestyle more similar to the one we see in Florida. The Florida Manatee is actually called the West Indian Manatee because the geographic area it covers begins in Florida and continues into the Caribbean.
Manatees today are warm water mammals, but the now extinct Stellar’s Sea Cow, was a cold water animal living in the Bering Sea near Siberia. The largest of the Manatees, they grew up to lengths of 25 feet and weighed over 5 tons. Discovered in the mid 1700s, the Stellar’s Sea Cow was hunted to extinction in less than 30 years.
Greek and Roman mythology speak of a female enchantress who was half woman and half fish. This woman, called a “siren” is said to have beckoned sailors at sea. The legend also calls these woman “mermaids” and it is believed that what sailors actually saw were manatees. Columbus noted that the mermaids he saw were not as attractive as the artists renderings.
Manatees are herbivores, feeding off sea grasses and aquatic plants. They have a low metabolic rate, but eat eight to ten hours a day. Their ability to regulate their buoyancy allows them to feed comfortably at different levels. Because their skin offers minimum protection against cold water, manatees migrate toward inland fresh water for the winter and back to salt water during the summer. Calves stay with their mother for about two years, first nursing and then learning how to find food and warm water. Florida is the only state where manatees can be found throughout the year.