Manatees
...to move the food into place. Last of all, behind the lips, special ridged pads break food into smaller pieces before the molars finally grind it up. Keeping warm is a real problem for these manatees. Their cylindrical bodies help conserve heat, but they do not have the blubber that other marine mammals do. Their metabolism is also very low, so they do not generate a lot of body heat. As a result, manatees can get sick when the water temperature falls below 70° F. In cold water, they can develop pneumonia, get too sluggish to eat, and can die. Most manatees live in warm, tropical waters, but Florida manatees live in sub-tropical waters that get below 70° F in the winter months, which are December through March. Manatees have a behavior which helps them survive in the colder water. In the winter, they seek out the natural warm springs of Florida's coastal rivers. They even gather where electric power plants discharge warm water. To protect manatees, many of these areas are now Manatee Sanctuaries. Because manatees are such large animals, they have few predators. Yet, they are one of the most endangered marine mammals. They are listed as vulnerable to extinction, which means that if their numbers do not increase and their habitats are not protected, the species may not survive. Collisions with boats, getting tangled in discarded fishing lines or nets, and swallowing hooks or other trash are some of the dangers that manatees face. To add to their problems, manatees have a very slow reproductive cycle. Cows give birth only once every three to five years. At present, the numbers of deaths (natural and human related) are greater than the number of births. The West Indian manatee population is estimated at only about twenty-five hundred. People are the major threat to these animals. Manatees are slow, non-aggressive animals which makes them easy to hunt. In the past, humans hunted manatees extensively for their meat, fat, and tough hides. Their large bodies have a lot of meat, so a single animal can feed a large family for a long time. In the United States, hunting is not the major problem, but habitat is. A quiet water habitat that can provide one-hundred pounds of water plants per day per manatee is key to their survival. Residential and commercial development along rivers and waterways has affected the manatee population. Habitat destruction has damaged the estuarine sea grass communities on which manatees depend. Ames and Van Vleet stated that “one aspect of manatee survival that we know little about is the accumulation and toxicological effects of chlorinated pesticides.” Chemical pollution has impaired the immune systems of marine mammals, and the manatees may have become more vulnerable to infection as a result. Powerboats are now the greatest threat to manatees. They are responsible for “about half of the manatee death” (Science News 22). Manatees are slow, near-surface swimmers, and the number of collisions with motorboats is increasing at an alarming rate. “The number of documented mortalities is only a minimum estimate of the direct impact of boats on manatees; it does not include animals struck by vessels but not killed, or those killed but whose carcasses were not recovered or found” (Nowacek et. al. 1). In 1990, two-hundred-eighteen manatees, which comprised twelve percent of the United States' manatee population, were killed in boating accidents, and many more were injured. One of the ways that scientists learn about an animal is by closely monitoring its behavior. This can be difficult to do with an animal that can easily disappear underwater. To keep track of manatees for study, scientists attach a special float to their tail. Inside the float is a transmitter. Using a special radio or a satellite, scientists can track the movements of the "tagged" animal. A recent project to capture, tag, and release manatees revealed that many bore the scars of encounters with speed boats. Scientists are studying these animals to better understand and protect them. In the meantime, people have acted to protect manatees. Many of the warm springs that attract them in the winter are protected sanctuaries. West Indian manatees in the United States are protected under federal law by the Marine Mammal Protection Act of 1972 and the Endangered Species Act of 1973, which make it illegal to harass, hunt, capture, or kill any marine mammal. Conviction on the federal level is punishable by a ...