Florida Manatees

The West Indian Manatee/Florida Manatee (Trichechus Manatus)

The Florida Manatee, as you see above, is the species we South Floridians are most likely to observe as we go about our days on the coastal waterways.  Just as many human tourists or “snowbirds” prefer not to be stuck in the cold, manatees also seek warm water as temperatures drop. These gentle giants are fascinating marine mammals that are known for their slow, peaceful demeanor.

Appearance:

Adults weigh from 900 – 1200 pounds on average; and are commonly from 9-13 feet long.  Their skin is generally gray but may appear more green or brown due to algae growth on their backs. It is a leathery and wrinkled skin which flakes off keeping algae and barnacles from build-up.   Because of their poor vision, the manatees’ facial whiskers (called vibrissae which are similar to small antennas), appear to assist with navigation and locating plants for feeding.  Flippers are used for swimming, turning, bottom walking, and manipulating food.  Despite the “look” of fat content, manatees have more muscle and solid bones which gives reason for its’ slower movement and the necessity for a warmer living environment.

Habitat and Diet:

Manatees are found in a range of coastal and estuarine habitats as well as rivers and canals.  They eat aquatic plants and can consume emergent and submerged vegetation from freshwater, brackish, and saltwater environments.  Each day these mammals eat around 120 pounds of food or up to 10% of their body weight thus earning the nickname “sea cows”.  Their favorite foods are seagrasses and mangrove leaves, with occasional small fish attached to a plant, like an underwater salad bar.   This diet of rough vegetation means that the manatee’s molar teeth wear down rapidly causing them to shed continuously.  New teeth grow at the back of each row; then migrate forward during their lifetime (like a conveyor belt). 

Behavior and Family Life:

Manatees move slowly through inland and coastal waterways at a rate of about 5 mph but can swim in short bursts up to 15 mph.  Manatees surface for air every 3-5 minutes and can stay submerged for up to 20 minutes while resting.  They travel from north to south along both Florida coasts striving to keep to waters that are at least 68 degrees F.  Primary travel is solitary, but they occasionally form small transient groups for short time periods. The manatee reproductive rate is low, with a female giving birth every 2-5 years; and the gestation period  lasting one year.  At birth a manatee will weigh an average of 66 pounds.  The calf will then be dependent on “mama manatee” for 1-2 years.  “Papa manatee” … is long gone!  Lifespan in the wild is estimated to be 50+ years and at least one in captivity survived an incredible 69+ years.  Manatees, especially mothers and calves, communicate through faint squeaks, chirps, and grunts while also utilizing tactile senses of short bristly body hairs.

Threats:

Manatees have no natural predators.  The largest threats to these beloved mammals are habitat loss, collision with boats, fishing net entrapment, sewage, and fertilizer run-off. 

Florida Manatees have definitely been spotted around Deerfield Island Park.  I personally have seen only three in the 9 years I have lived in this beautiful area (two were swimming together on the northeast corner of the Island and one was in a cove swimming next to the shore).

Here is an interesting study researching “Manatee Communication Sounds” 

https://savethemanatee.org/manatees/manatee-facts  then select  ‘Communication Sounds ‘

Submitted by Karen Hutson