Manatees average about 10 feet in length. Large individuals may reach lengths of up to 13 feet. Average adult weights are approximately 800 to 1200 pounds, with big individuals weighing up to 3500 pounds. Female manatees are generally larger than the males. All manatees have sparse hair scattered over their bodies.

The manatee is streamlined, full around the middle and narrowing to a paddle shaped tail. Manatees are usually grayish brown. Organisms such as algae may grow on these slow moving creatures, helping to determine their coloration. They are very agile swimmers and maneuver quite well underwater, and have been clocked up to 15 MPH for short bursts, but generally cruise at a sedentary speed of between 2 and 6 MPH.

Manatees generally feed no deeper than 10 feet below the surface of the water. While resting, manatees can stay underwater for as long as twenty minutes, although they generally will average 2 or 3 minutes between breaths. Manatees are gentle, non aggressive, non territorial herbivores that spend most of their time feeding (6 to 8 hours a day), and resting (2 to 12 hours a day). The remainder of their time is spent traveling, curiously investigating objects and socializing by mouthing, rubbing against, and interacting with other manatees.

Manatees in Florida feed on over 60 species of plants. These include turtle grass, manatee grass, shoal grass, mangrove leaves, various algae, water hyacinth and water hydrilla. Manatees avoid specific plants such as splatterdock and waterpennywort that contain natural toxins. They consume about 4 to 9% (32 to 108 pounds) of their body weight in wet vegetation daily. Manatees feed off the bottom, in the water column and at the surface. They have even been know to crop overhanging branches, consume acorns and haul themselves partially out of the water to eat bank vegetation.

Manatees use their front flippers and large flexible lips to manipulate vegetation. Horny ridged pads at the front of a manatee's palate and lower jaw break vegetation into small pieces. Behind these pads, molars grind the food.
Manatees have been seen drinking fresh water from hoses, sewage outfalls, culverts and other fresh water sources and also congregating at river mouths. Most scientists agree that manatees must have access to fresh water periodically.

Male manatees are also known as bull manatees and probably reach sexual maturity at about nine or ten years of age. Female or cow manatees are probably sexually mature by about seven or eight years of age. Manatees don't form permanent pair bonds. Manatee gestation is about 12 months. Manatees in Florida apparently breed year rounds with most calves born in the spring and summer months. A cow gives birth about once every three years. The calf can be born either head - or tail-first. Births of twins may occur but are extremely rare. A manatee calf measure about 4 to 4.5 feet and weights approximately 60 to 70 pounds. The newborn calf is capable of swimming to the surface on its own. Calves vocalize at or soon after birth. This is an important part of the mother-calf bonding process. The calf begins to nurse within a few hours after birth by suckling from a teat under the pectoral flippers. Calves nurse underwater. Calves begin nibbling on plants within a few weeks of birth. Although it may be weaned by the end of its first year, the calf remains close to its mother for up to two years. The calf is dependent on it s mother not only for nutrition but also for learning about feeding and resting areas, travel routes, and warm water refuges.

Manatees probably live a maximum of 50 to 60 years. Manatees are very susceptible to cold weather. It's not unusual for many to die during extremely cold weather. In 1990, 47 manatees died due to cold weather.

Due to their dark color and because they are slow swimmers, manatees are difficult to see in the water. Many manatees are injured and killed by propellers and hulls of speed boats. Collisions with boats and barges is the largest human related factor causing manatee death in Florida.
The Florida manatee is one of the most endangered marine mamals in the United States. Federal and state laws have been passed that protect Florida manatees. Federal laws prohibit hunting capturing killing or harassing these animals. These laws include the Marine Mammal Protection Act of 1972 and the Endangered Species Act of 1973. The Florida Manatee Sanctuary Act of 1978 is state legislation establishing Florida as a sanctuary for manatees.