Description - West Indian Manatee The West Indian manatee is a large, gray-brown, aquatic mammal. Its seal-like body tapers to a flat, paddle-shaped tail, and two forelimbs on the upper body have three to four nails on each flipper. The head and face are wrinkled and the snout has stiff whiskers. Adults have been known to exceed lengths of thirteen feet and weigh over 3,500 pounds; however, this is quite above average. Manatees usually average around 10 feet in length and weigh somewhere between 800 and 1200 pounds. At birth, manatees are three to four feet long and weigh between 60 and 70 pounds.

Anatomy and Physiology Manatees have a large digestive system, and unique, continuously replacing molars to cope with an herbivorous diet. The manatee eats abrasive plants that wear down these molars. As an adaptation, new molars form at the back of the jaw and move forward, pushing out the oldest, most worn-out teeth. The rate of molar movement depends on how fibrous the plants are. The manatee's eyes are small and have a nicitating membrane that can be drawn across the eyeball for protection. Manatees have farily good visual acuity and can distinguish between different-sized objects, different colors and patterns. Manatees emit sounds underwater that are believed to be used in communicating with one another, and not for navigational purposes. Vocalizations may express fear, anger, or sexual arousal. They are also used to maintain contact, especially when manatees are feeding or traveling in turbid water. Especially common are vocalizations between cow and calf. (A cow and calf once separated by a flood gate vocalized constantly for 3 hours until reunited.) Adult manatees move through the water primarily by the pumping action of the tail. The front flippers are used for steering and lateral movement or crawling over the water bottom and also for putting food into the mouth. Young manatees seem to propel themselves with their flippers. Because manatees are herbivors and have a slow metabolic rate, they need to be in warm water.

Behavior Manatees spend most of their time feeding (six to eight hours a day) and resting (two to twelve hours a day). They graze for food along water bottoms and on the surface. They may rest submerged at the bottom or just below the surface, coming up to breathe on the average of every 3 to 5 minutes. Intervals between breaths depend upon activity level. When the manatee is using a great deal of energy, it may surface to breathe as often as every 30 seconds. When just resting, manatees have been known to hold their breath as long as 20 minutes. Manatees are agile and have been observed in loosely organized, playful activities such as body-surfing and barrel rolling. Manatees are not territorial. Because manatees have evolved with no natural enemies, they have not needed the protection / cooperation of a herd. Consequently, they are semi-social, somewhat solitary animals. They sometimes gather in small, informal groups, but have no leader, or real structure.

Breeding and Reproduction Manatees do not form permanent pair bonds. During breeding, a single female, or cow, will be followed by a group of a dozen or more males, or bulls, forming a mating group. 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, although twins have also been recorded. Intervals between births range from two to five years (a two year interval may occur when a cow loses a calf soon after birth). The gestation period is approximately thirteen months. Mothers nurse their young for a long period and a calf may remain dependent on its mother for up to two years. The cow assumes total responsibility for raising the calf. Calves nurse under water from a nipple located behind the cow's flipper and begin to eat plants a few weeks after birth. Scientists believe females do not become sexually mature until five years of age. They live long lives - it is believed the manatees are capable of living 60 years or more. One manatee in captivity is now over 47 years old, but because of the many perils in the wild, longevity is uncertain. Because the reproductive rate is so low, the species as a whole adapts very slowly to changing situations or unnatural stress. The current population is estimated at a minimum of 2,600 animals. The manatee was officially declared endangered in 1973, as part of the original endangered species listing for the Federal Endangered Species Act.

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