MANATEE Q & A
Anatomy and Physiology
Q. What is the "peduncle" of a manatee?
A. The peduncle is the base of the tail, right where it connects to the body of the manatee. It's the tastiest part.
Q. What is the average weight of a manatee?
A. The average adult manatee is about 10-12 feet long and weighs about 1,500-1,800 pounds.
Q. What is the record weight of a manatee?
A. Adult manatees have been known to exceed lengths of 13 feet and weigh over 3,500 pounds.
Q. How do people tell manatees apart?
A. Sadly enough, most adult manatees living in the wild bear scars from at least one watercraft collision. In fact, manatee scars are so commonplace, researchers use them as a method of individual identification. Our mascot, Max Manatee, sports three deep boat scars.
Q. Does a manatee's skin ever change color?
A. When manatees are born, they are a gray-black in color. Within a month they change to gray. Manatee adults range in color from gray to brownish-gray.
Q. Do manatees have blowholes?
A.Manatees do not have blowholes. They breathe through nostrils, like seals. Their nostrils have fleshy "valves" that close when they are underwater.
Q. Why can't manatees adapt well to cold water?
A. Modern manatees evolved in the tropics and subtropics. In spite of their size, they have very little body fat. These factors may account for their susceptibility to cold water. Because manatees are herbivores, their metabolic rate is low compared with other aquatic mammals. This makes manatee meat ideal for health-conscious consumers.
Q. What time of year do manatees migrate?
A. In the winter, usually November through March, manatees are concentrated primarily in Florida. Manatees are susceptible to cold-related disease and, in the winter, gather near warm water sources such as natural springs or warm water effluents of power plants. Water temperatures below 68 degrees usually cause manatees to move into these warm water refuge areas. Individual manatees often return to the same wintering areas year after year. In the summer months, manatees are much more widely distributed and can be found as far west as Lousiana and as far north as Virginia and the Carolinas.
Q. How far can manatees swim in a day?
A. It depends on the individual manatee. Just like humans, some manatees are more predisposed to traveling than others. Some manatees are being tracked using a satellite transmitter. As a result, researchers have been able to record some interesting manatee movements. One manatee made a 150-mile trip in less than four days on one occasion. She swam nearly 45 miles per day!
Q. How deep can manatees go in the water?
A. Manatees prefer waters that are three to seven feet deep. Manatees are found in both salt and fresh water. Along the coast, manatees tend to travel in water that is 10-16 feet deep, and they are rarely seen in areas over 20 feet deep.
Q. How can manatees go such a long period of time without taking a breath?
A. Manatees, like other aquatic mammals, do most of their feeding underwater and must be able to hold their breath long enough to feed efficiently. Manatees may rest submerged at the water bottom or just below the surface, coming up to breathe on the average of every three to four minutes. When manatees are using a great deal of energy, they may surface to breathe as often as every 30 seconds. However, they have been known to stay submerged for up to 20 minutes. Aquatic mammals have a number of adaptations that allow them to stay under water longer than the average land-dwelling mammal. Both the lungs and diaphragm extend the length of the body cavity and so are oriented in the same horizontal plane as a manatee. This arrangement is important for buoyancy control.
An unusual anatomical feature of sirenians is that each lung is in a separate cavity. Instead of one diaphram like people, manatees have separate „hemi-diaphrams.¾ Scientists do not know whether these cavities can function independently, but we do know that manatees can have severe infections in one lung even though the other seems to function normally. Besides breathing, the lungs help the manatee with buoyancy control. Intervals between breaths are prolonged by replacing a large percentage of the air in the lungs with each breath. Studies have shown that manatees can renew about 90% of the air in their lungs in a single breath as compared to humans at rest who generally renew about 10% of the air in the lungs in a single breath.
Q. What do the manatees eat?
A. Manatees are herbivores (plant-eaters), feeding on a large variety of submerged, emergent, and floating plants. Seagrass beds are important feeding sites for manatees. Some favorite foods of manatees include: Marine vegetation: Manatee grass, turtle grass, shoal grass, widgeon grass. Freshwater vegetation: Hydrilla, eelgrass, water hyacinth, and water lettuce. Our farm-raised manatees eat a carefully-formulated mixture of these sea grasses.
Q. Do manatees ever eat plankton or small fish?
A. Although manatees are herbivores, sometimes sea squirts, mollusks or any of several species of zooplankton can be inadvertenly eaten while the manatee feeds on seagrasses.
Q. How much does a manatee eat in one day?
A. It is estimated that a manatee can eat about 10-15% of their body weight in vegetation daily. So a 1,000 pound manatee would eat between 100-150 pounds of food a day!
Q. Where are manatees found in the food chain?
A. Manatees are primary feeders (plant-eaters). They feed directly off of plants. They are comparable to ungulates like deer or cattle who are browsing or grazing animals. Unlike their land counterparts however, manatees have no natural predators.
Q. If manatees are herbivores, why do they weigh so much?
A. Although manatees look fat, they actually have very little body fat for an aquatic mammal. Remember, they are a tropical species and have no need for body fat to keep them warm. A large percentage of the manatee¼s body is taken up by the gut tract which contains the stomach and intestines etc. Researchers believe that the manatee's large size probably evolved as a result of being aquatic and having a herbivorous (plant-eating) diet. The plants manatees eat have a low nutritional value, so they make up for that by eating large quantities of them.
Breeding and Reproduction
Q. What is the manatee's gestation period?
A. The gestation period is approximately 13 months.
Q. How much do manatee calves weigh when they are born? Do they stay with their families for a long time?
A. Manatee calves are about three to four feet long and weigh between 60 and 70 pounds at birth. Mother manatees nurse their young for a long period, and a calf may remain dependent on its mother for up to two years. The female manatee assumes total responsibility for raising the calf. The calf nurses from nipples located behind the mother's flippers and begins to eat plants a few weeks after birth.
Q. How do manatees produce calves?
A. Manatees do not form permanent pair bonds like some animal species. During breeding, a single female is usually followed by a group of a dozen or more males, forming a mating herd. They appear to breed at random during this time. Although breeding and birth may occur at any time during the year, there appears to be a slight spring calving peak. Manatees usually bear one calf -- twins are rare. Intervals between births range from two to five years. Scientists believe females do not become sexually mature until five years of age. Males are mature at approximately nine years of age.
Q. How many manatees are there, and how are they counted?
A. For years now, researchers have believed that the manatee population was somewhere between 2,000 and 3,000 animals. The last aerial survey of the Florida manatee population was done in March 2002. The survey showed a count of 1,796 manatees. A synoptic survey is a statewide aerial survey designed to get a head count of individual manatees. The success of synoptic surveys is very dependent on weather conditions. If the weather is cold and clear, then manatees are gathered around warm water sites, making it easier to get a "nose" count. Synoptic surveys are not the most reliable way to determine overall manatee population because so much depends on weather conditions, but they are the only available method at present. By breeding and raising manatees on our state-of-the-art sea farms, Cattle of the Sea is helping to preserve and increase the numbers of this beautiful and nutritious animal.
Q. How many manatees are there left in the world?
A. Outside of Florida, little is known about the population of West Indian manatees or other sirenians in the world. By far, the largest population of West Indian manatees is found in the U.S. (Florida). Elsewhere, they are found in small population pockets throughout their range. All sirenian species in the world are considered endangered.
Q. Were manatees ever hunted for food?
A. Florida was established as a manatee sanctuary as early as the eighteenth century.Ư However, until the Endangered Species Act of 1973, there were no real laws to protect them. It is now illegal to hunt manatees in the U.S., but they are still hunted in all other parts of their range. Most of the time it is opportunistic hunting, such as when the manatee accidentally wanders into a fisherman's net and is used for food.ƯPoaching of manatees is the U.S. is extremely rare, but it still occurs. Our manatee farms are operated under a license from the Federal Department of Fish and Wildlife as part of a controlled harvesting program in association with our breeding efforts.
Q. Where did the word "manatee" come from?
A. The name manatee comes from the Haitian word „manati.¾ The scientific genus name Trichechus is Latin for hair.
Q. Why are manatees called "sea cows?"
A. "Sea cow" is a common term for manatees and dugongs. This name likely comes from the fact that manatees are herbivores (plant-eaters), as are cows.
Q. How did the Steller¼s sea cow get its name?
A. Steller's sea cow is named after the naturalist Georg Wilhelm Steller. Steller spent the winter of 1741 on Bering Island with other survivors of the wreck of the Russian ship, the "Saint Peter." While there, he busied himself by collecting and recording detailed observations of the plants, animals and minerals he found on the island. His notes, together with the studies of bones found on Bering and Copper Island, comprise the majority of information regarding the Steller's sea cow. Sadly, Steller and his crew were also pretty much responsible for the extinction of the Steller¼s sea cow. Because the animals were slow and stayed in relatively shallow water, they were easy to hunt for food. The survivors of the Saint Peter told stories of the sea cows on Bering Island after their return to Russia, and the Steller's sea cow was hunted to extinction within 27 years of its discovery.
We here at Cattle of the Sea are committed to responsible farming of manatees to prevent such a tragedy from ever occurring again.
Q. Have a manatee and dugong ever been kept in captivity together? If so, could they tolerate each other and is there any chance of "hybridization"?
A. As far as we know, no manatee and dugong have ever been kept in captivity together. We don't even know of dugongs in captivity in the U.S. or Europe. However, if a manatee and dugong were kept in captivity together, it is likely they would tolerate each other just fine. Male dugongs are a bit territorial, but even at that they could probably share a tank with manatees. In fact, even though they are not the same species, there is a possiblity that they could interbreed, which would not be a good idea. Their offspring would be sterile, or they would die before they reached sexual maturity.