By Mary Lundeberg – Our state marine mammal, the Florida Manatee (Trichechus manatus latirostris), is a subspecies of the West Indian Manatee. Gentle and slow moving, this remarkable animal can weigh more than 3,500 pounds and grow 13 feet in length. It’s always a delight to see one popping their nose out of the water as they coexist with kayakers, boaters, and other humans enjoying our life-giving waterways. Called sea cows because of their size and grazing behavior, manatees are natural weed-control agents consuming up to 150 pounds of aquatic plants each day. As the only completely herbivorous marine mammals, they have no predators and have evolved no defenses.
Manatees prefer shallow water where they can forage and rest on the bottom. Because they cannot tolerate water temperatures colder than 68 degrees, they travel from the ocean to warmer water in the winter season. Good destinations include warm water springs and artificial warm water sources like the power plants in Tampa and Fort Myers. Because they are mammals, manatees need air to live. Normally, they breathe every 2-5 minutes, but they can remain submerged up to 20 minutes. When manatees surface, they open their nostrils for air, and when they dive, the nostrils close as you can see in the photo.
Manatees use their front flippers to steer and to hold vegetation while eating. Their flattened tail allows them to undulate as they swim, so slowly that algae and barnacles often attach themselves to their skin. Manatee females give birth every 2-5 years to a calf weighing about 70 pounds and measuring 3 feet in length. The calf stays with its mother for one to two years nursing from a nipple located under each flipper, and eventually learning how to forage.
It is illegal to harass, hunt, kill, capture, or feed wild manatees. By offering lettuce or water to manatees, we invite them near boats, which puts them in danger. Over 85 percent of manatees show scars from boat propellers. Many are killed each year. Other threats include red tide, toxic blue-green algae, seagrass decline, pollution, habitat loss, and cold weather. Wild manatees live about 50 years.
Another threat is the weed-killing pesticide glyphosate. A recent study found glyphosate in more than half of Florida’s manatees. It may explain the alarming number of deaths (539) so far this year.
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