West Indian Manatee - Island Ecology UNCW 2016 (2023)

Trichechus manatus

Description

Giant, gentle, and can be seen from North Carolina to Northern Brazil, the West Indian Manatee is a widely loved nomadic creature. There can be found two sub-species of West Indian Manatee- Florida Manatee (Trichechus manatus latirostris) and the Antillean manatee (Trichechus manatus manatus). Adult manatees are around 10-12 feet long, and 2,000 lbs of love. Their

bodies are covered in sparse hairs, and wrinkles, while their muzzles are covered in stiff whiskers. These animals, when active, surface every couple of minutes for air, but have adapted to hold their breath for as long as 25-30 minutes. West Indian Manatee's can be any colour from black to grey to brown. Often wearing a coat of algae, Manatee's are known as "sea cows", for it's great body mass and constant munching on various grasses and plants.
They are found in warm, shallow, salty bodies of water such as lagoons, estuaries and coastal rivers. These animals, despite their size, are agile swimmers and are thought to have been called "Mermaids" by European explorers, such as Christopher Columbus.This very cute marine mammal is endangered, partially due to hunting, which is now illegal but still are at risk because of boats, dams, and other interactions with humans.

Photo Credit: Sarah Hayden, Florida US

Often times, Manatees are curious and have much interaction with Humans during "Manatee swims".

Photo Credit: Richard Wylie

Taxonomy

Common Names: Sea Cow, Mermaid, Sirens

Kingdom Animalia

Phylum Chordata

(Video) Movement Patterns of West Indian Manatees | Felice Knowles | BNHC 2016

Class Mammilia : Mammals

Order Sirenia : Related to 'mermaid' myths or sirens

Family Trichechidae

Species

Trichechus

"Manatees belong to the order Sirenia of which there are only 4 extant species in 2 families, Trichechidae and Dugongidae. The West Indian manatee (Trichechus manatus), the West African manatee (Trichechus senegalensis), and the Amazonian manatee (Trichechus inunguis) are members of the family Trichechidae. The dugong (Dugong dugon) is the only surviving member of the family Dugongidae (Reynolds and Odell 1991). Steller's sea cow (Hydrodamalis gigas) is also in the family Dugongidae (Reynolds and Odell 1991), but the species was extirpated by humans in 1768 just 27 years after it's discovery in the North Pacific (Stejneger 1887)."

Caryn Self-Sullivan, Ph.D. Visit website here.

Manatees are more related to elephants than other underwater mammals, such as the whale or dolphin. This is partially due to the shared trait physical traits. An example of this is a rounded heart, as opposed to most mammals who have a pointed tip that makes their heart...well, "heart" shaped, elephants and manatees share this. Manatees and elephants also have strong structures near their mouths to help steer food into them, fingernails, and molars that are replaced. You can see some of these features in the videos down below, with Snooty! Both these animals reproduce very slowly, which contributes to them being endangered. We see similar trends in their number declination; human predacious activities and habitat loss.

Sketches of different manatee & dugong families that belong to the order

Sirenia. Steller's Sea Cow was found in the North Pacific Ocean. Unlike

it's related cousins, it was known to be almost mute.

Credit Sirenia.org/caryn

Manatees spend 3-8 hours eating a day

(Video) Movement Patterns of West Indian Manatees in The Bahamas | Felice Knowles | BNHC 2016

Niche & Life Cycle

"West Indian manatees prefer shallow, slow-moving waters of rivers, estuaries, saltwater bays, canals and coastal areas. They can move easily between freshwater and saltwater environments, but prefer freshwater.

Florida manatees are found primarily along the coast of Florida, the Gulf Coast and the Caribbean. During the winter, they migrate between Florida and the Caribbean. While seeking warmth and shelter, Manatees will congregate near power plants and springs. The summer grounds are as far north as North Carolina, and towards Texas. There have been sightings in Rhode Island. Cold weather has been known to kill manatees. Because of their

low metabolism and lack of insulating body fat, manatees prefer shallow, warm coastal rivers and bays.

Antillean manatees are found in the Caribbean, in the Gulf coasts of Central America, and in northern and eastern South America as far south as Northern Brazil. During warmer months they are found near adequate food supplies.

During a manatee's long life about 30 years in the wild, Manatees reach sexual maturity around 3-10 years of age. Manatees will have one or two calves every two to five years. There is no "breeding period" for manatees- but gestation does last up to 13 months. The calves are born with teeth, and can start eating plants almost instantly, they will still nurse for a few minutes before coming to the surface. This may continue for up to two years. Newborns can be up to 5 feet long and weigh 50-70 lbs.

The parent will call to the calf using chirps, whistles, squeals and squeaks.

Distribution map

Credit: Save that manatee

Friends & Foes

Manatees are great herbivores. It is often thought that these gentle mammals that brave the ocean could be subject to attacks from sharks. This doesn't happen often because there is no conflict or competition for food, and due to their large size. Calves and small manatees may be subject to attack if they straggle, but for the most part, Manatees stay in loose groups and calves are often near their mother for two years. Staff Biologist Courtney Edwards of Save The Manatee Club says
"Humans account for almost 39% of manatee deaths, where the cause of death is known. This includes deaths from watercraft, locks/canals, and other human related sources, such as discarded fishing line. In some places around the world, hunting for manatees is still a part of many cultures. Other non-human related threats to manatees are red tide and cold stress. "

There are instances of symbiosis with the manatee. The manatee often has a coat of algae and other various plant life living on it's back, smaller fish can be found cleaning the vegetation off of the manatee and even partaking in leftovers. There have been some instances of meat eating among manatees, but these seem to be mostly accidental.

Even off the coast of North Carolina and in the Cape Fear River where sea grass grows these animals are at risk for boating accident and staying in areas where they are fed. If seen, UNC-Wilmington asks that you call and report the sighting. A quick article can be found to answer some question about the Do's and Don't's of Manatees in the greater Wilmington area, here.

(Video) Manatees: Conserving a Marine Mammal - Full Episode

Evolution and Environmental Impacts

The West Indian manatee is not adapted to colder waters, nor holding it's breath for long periods of time like other marine mammals, such as whales. For this reason, the manatee seeks out shallow, warm and slow moving bodies of water. The manatee due to it's herbivore nature has a very slow metabolism and can eat from 32-100 lbs of plants a day. No evidence of proper weed and algae control has been noted in Floridian Manatees, but are claimed to be used in South American regions.

This animal has no natural predators but due to many run-in's with human, have experience a population decline. Today, these manatees are protected in the US, and are often used as an indicator species for Southern Florida habitats.

Manatee snuffling for food in a shallow Floridian waters.
Photo: Sarah Hayden, Florida

Conservation

"Manatees were hunted historically but now are protected under the Marine Mammal Protection Act, which prohibits the take of all marine mammals. Today the biggest threats to manatee survival are collisions with boats and loss of warm water springs that provide important habitat, but they are also vulnerable to entanglement in fishing gear, red tide blooms and loss of seagrass beds they feed upon due to pollutants. They are considered endangered and their survival is seen as limited due to their low reproductive rates."

National Wildlife Federation

Historically they were hunted, and sometimes still are in South America; their meat and bones are valued to have medicinal properties.

Modern conservation has taken big steps to ensure that manatee accidents are kept to minimum by educating commercial businesses, individuals, and water-way laws. As a matter of fact, Federal Wildlife Services have a list of actions for people who dredge or who are operating machinery around the Cape Fear River and coast to follow; like stopping activities until manatees have passed or have been relocated.

Individuals can do their best to save manatees by making sure not to feed or pet them. It is often mentioned that even spraying them with a hose will encourage them to stay somewhere because they come to fresh water to drink. If on a boat and a manatee is seen, be very careful because many manatees suffer serious injuries every year. It is highly recommended to call local officials to report a siting so proper precautions can take place.

Videos

Manatee Endangered Status Change:

Highlighting some of the dangers to the Manatee.

(Video) Manatees and Florida's Springs