• Biodiversity West Indian Manatee
  • The West Indian Manatee

    Trichechus manatus

    An Underwater Omnivore – A General Description

    The West Indian Manatee is a giant, omnivorous aquatic mammal that is a distant relative of elephants and hyraxes. This particular species has at least two recognized subspecies, the Florida Manatee and the Antilles Manatee. A third subspecies in Northeastern Brazil may be universally recognized however as molecular data was collected from Garcia-Rodriguez et al. (1998). This page is based primarily on research from the Florida subspecies as this subspecies has had more research than any other subspecies or manatee species. While this species is technically referred to as the West Indian Manatee, this page often refers to the species as simply as the Manatee or when referring specifically about the Florida subspecies, as the Florida Manatee.

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    The first thing people notice about the manatee when they first encounter one is its size. The West Indian Manatee (Manatee) can grow to more than 3000 pounds and over 13 feet in length. In some ways, it is easy to see how it could be related to elephants. It has a similar color, grey or grey-brown, and the skin is thick and wrinkled. Manatees use their snouts to dig through sediment. The snout is thick and covered in stiff whiskers on the upper lip.

    Behavior

    All manatees are gentle, slow-moving animals. Most of their time is spent resting, eating, or traveling. They are usually quite shy and reclusive but may come up to humans if they have had a history of being fed by them.

    Manatees have evolved in areas where there are no natural predators and thus have no natural predator evasion behaviors. This makes them easy targets for hunting. One of the West Indian Manatee’s relatives, the Steller’s Sea Cow which lived in the Bering Strait, was decimated by hunting only 27 years after it was discovered by humans.

    Sight: The depth perception of a manatee isn’t great. They have very small eyes. However, it has been shown that they can differentiate colors.

    Hearing: Manatees can hear very well despite the absence of external ear-lobes.

    Communication: Manatees emit sounds that are within human auditory range. They will squeak or squeal when frightened or communicating, particularly between cow and calf.

    Breathing: A manatee breathes through its nostrils which are on the upper surface of its snout. When a manatee submerges, their nostrils close tightly. Depending on the amount of activity, a manatee will breath every few minutes.

    Habitat: Where are Manatees found?

    Manatees can be found in shallow, slow-moving rivers, estuaries, saltwater bays, canals, and coastal areas, particularly where sea-grass beds flourish.

    Range: The Florida Manatee is restricted to Florida in the winter months. In the summer, they can be found as far west as Louisiana and as far north as Virginia and the Carolinas. The subspecies of West Indian Manatee known as Antilles Manatee is found in Central and South America as far south as Brazil.

    Diet: What do Manatees eat?

    Manatees are completely herbivorous and eat aquatic plants.  They can eat ten to 15 percent of their body mass in food each day.

    Natural History

    Manatees are believed to have evolved from wading, plant-eating organisms. They are believed to share a common ancestor with the Elephant and Hyrax.

    Abundance: There are approximately 1200 left in the wild.

    Reproduction

    Female Manatees become reproductively mature when they are five to nine years old and males from six to nine years old. Once pregnant, female manatees have a gestation period of 13 months. They can have one calf every two to five years. Twins are very rare in the wild. The young calf will stay with the mother nursing for two years. After that time they spend another year with the mother.

    How long do manatees live?  Florida Manatees may live to be more than 60 years old in the wild.

    Conservation Efforts

    Manatees were listed as endangered species under the U.S. Endangered Species Act of 1973. The US Fish and Wildlife Service recommended in 2007 that the Florida Manatee be reclassified as “threatened” instead of “endangered.” While the Florida Manatee has rebounded, there is controversy because this act takes significant protection off of the manatee. The International Union for Conservation of Nature has recently placed it on their Endangered List (October 2007) because of the low numbers of the breeding population (under 2500) and that the population is estimated to decline by 20 percent in the next 40 years.

    Current threats to Florida Manatees are almost all human activities. These threats include loss of habitat, boat propellers that hit the manatees, being crushed or drowned in flood gates, poaching and ingestion of lines and hooks. In addition to direct human threats, many manatees are also affected by natural disasters like hurricanes and red tides.

    Related Species: West African Manatee, Dugong, Steller Sea Cow, Amazonian Manatee

    Resources

    Garcia-Rodriguez, B. W. Bowen, D. Domning, A. A. Mignucci-Giannoni, M. Marmontel, R. A. Montoya-Ospina, B. Moreales-Vela, M. Rudin, R. K. Bonde, and P. M. McGuire (1998). “Phylogeography of the West Indian manatee (Trichechusmanatus): How many populations and how many taxa?”. Molecular Ecology 7: 1137–1149. doi:10.1046/j.1365-294x.1998.00430.x.

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    Written by Rob Nelson

    Rob is an ecologist from the University of Hawaii. He is also an award-winning filmmaker. As principle director of Untamed Science productions his goal is to create videos and content that are both entertaining and educational. When he's not making science content, he races slalom kayaks and skydives.

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