With a face only its mother could love, a body able to discourage any predators just because of its large size and the knack for gaining popularity even as its population decreases, the Florida manatee has become an icon of Florida wildlife.
Florida has passed many laws to protect manatees – beginning in 1893. Since 1907, a $500 fine has been imposed on anyone who harms or kills a manatee. The manatee itself was listed as an endangered species in 1967, and protected under the Marine Mammal Protection Act of 1972 and by the Convention on International Trade in Endangered Species of Wild Fauna and Flora (CITES) treaty in 1973. The State of Florida was designated a refuge and sanctuary of manatees by the Florida Manatee Sanctuary Act in 1978, yet many years later, the manatee still faces the risk of being wiped off the face of the earth. A good look at the manatee’s characteristics, behavior and habitat reveals why.
The Florida manatee (Trichechus manatus latirostrus) is a subspecies of the West Indian Manatee – part of the sirenian order of mammals that includes manatees and dugongs around the world. Closely related to the elephant, the manatee is Florida’s state marine mammal. “Gentle giants,” as they are called, manatees are herbivorous, feasting daily on vegetation up to as much as 15% of their body weight, which includes very little fat. Averaging 10 feet long and 1,000 lbs., an adult manatee spends 6 to 8 hours eating, and the rest of the day resting or traveling.
Manatees are grayish brown in color, oftentimes influenced by the growth of algae on their thick and wrinkled skin. Their bodies resemble the seal’s, and their whiskered snouts look like the walrus’ without tusks. Forelimb flippers act like arms that allow them to maneuver, to “walk” in shallow water and to bring food to their flexible, grasping lips, while a powerful, flat tail propels their massive bodies across the water. It would be impossible to mistake this animal for anything but a manatee, but supposedly desperate sailors eager to find the New World thought that they had found the mermaids of legend, which is how their biological classification became Sirenian, of the order of Sirenia (sirens)
Able to hold their breath for up to 15 minutes while resting, manatees have huge lungs that exchange 98% of their contents in one breath. Their nostrils, located on top of their faces for easy breathing, have tight-fitting flaps that keep the water out when they’re submerged. Gushes of strong exhalation at the water surface reveal the manatees’ presence.
Manatees move slowly, and they are also slow to reproduce. Females mature in 5 to 9 years and give birth to one calf every 2 to 5 years. Young manatees nurse underwater, on teats under the mother’s flippers. When born, baby manatees are five feet long and weigh 100 pounds! They swim alongside the mother for about 2 years, learning travel routes and survival skills.
Manatees thrive in warm water. At temperatures below 68 degrees F, manatees stop eating, suffer cold stress and oftentimes die. This is why they migrate to the coastal areas, rivers, canals and estuaries in Florida and southern Georgia during winter. They especially prefer the slow-moving rivers and shallow coves and bays where there are warm springs and lush sea grass beds.
Manatees travel through freshwater, brackish and saltwater environments, reaching as far west as Louisiana and as far north as Maryland during summer. But in Florida, the favorite manatee migration destination seems to be Crystal River. And at Homosassa Springs State Wildlife Park, tourists come from all over the world to see the aquatic mammals. Manatees, however, find their way into any shallow river, estuary, cove or canal where feeding grounds can be found.
How does all this contribute to the manatee’s risk of extinction?
Natural causes that lead to the dwindling of the manatee population include diseases, red tide, predation from natural enemies and susceptibility to cold stress. Add to that the primary threat to all endangered species: the encroachment and destruction of natural habitat. In the manatee’s case, this is development along seagrass beds, mangroves and salt marshes.
To complicate the manatees’ situation even further, endangerment threats include harassment by humans, estimated as responsible for 43% of all manatee deaths. Fishing lines or nets carelessly thrown into the water get tangled in the manatees’ fins or tails, causing gashes that easily get infected. Speeding boats collide with slow-moving manatees surfacing for air, oftentimes killing manatees on impact. Boat propellers inflict fatal lacerations on the backs and tails of manatees swimming near the surface, unable to submerge fast enough to escape the blades.