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West Indian Manatees

West Indian Manatees

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  • Scientific Name: Trichechus manatus
  • Status in the Wild: Endangered
  • Habitat: Oceans, Rivers
  • Diet: Herbivore

The West Indian manatee inhabits shallow rivers, estuaries and saltwater bays of the Caribbean and Atlantic. This marine mammal may reach twelve feet in length and tip the scales at 1,200 pounds. The species is both nocturnal and diurnal, though Costa Rican manatees are believed to be most active at twilight and after sunset. West Indian manatees have a large, bulbous snout, a flattened tale, two front flippers, and gray or brown skin. Their closest living relatives are the elephant and the hyrax.

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The West Indian manatee is Costa Rica's only herbivorous, aquatic mammal. Manatees dine on at least 60 plant species, and prefer guinea grass, cola de zorro, water hyacinths and other plants common in coastal areas. They are voracious eaters, consuming up to 15% of their body weight each day. The resulting plant matter that ferments in their digestive track comprises hundreds of pounds of their total weight. In fact, this fermenting vegetation is the reason for the manatees' excessive flatulence – and the resulting bubbles are often the only visual clue to the mammal's whereabouts. 

Manatees are mostly solitary, but are known to act playfully in social situations. Though slow moving, they are very agile swimmers. Manatees emit chirps, squeaks and squeals, and are thought to have a basic vocabulary. Scientists do not think that manatees use echolocation. West Indian manatees have no natural predators, and it is believed they can live 60 years or more.

Habitat: 

West Indian manatees can live in fresh, brackish and salt water but they usually prefer the latter. They congregate near river outlets, and in freshwater that is slow moving and at least three feet deep. West Indian manatees live in the Atlantic Ocean and Caribbean Sea, ranging from Virginia (only in summer) south to Brazil's Amazon River. 

In Costa Rica, manatees inhabit the entire Caribbean coast, but are rarely seen due to their small populations. A late 1990's study estimated only 30-100 individuals remaining in the region. Additionally, manatees can be difficult to spot because their slow metabolism allows them to rest underwater for up to 20 minutes. When they do surface, they are able to renew 90% of the air in their lungs with just one breath. The only visual signs of the mammals' presence are rising bubbles or chewed aquatic grasses near the water's edge.

Reproduction: 

Manatees breed year-round, although they seem to prefer certain seasons in some regions. They are not monogamous, and several males will attempt to court one female during the mating season. Gestation lasts 12-13 months, and results almost exclusively in single births of calves that measure about 47 inches and weigh approximately 66 pounds. Manatee calves stay with their mothers for up to two years, but may feed on their own by their first birthday. Females reach sexual maturity between three and four years old, and will reproduce every two to five years.

Status in the Wild: 

The West Indian manatee has fallen prey to hunters for their meat, leather, bones and oil. Poaching in Costa Rica reached its peak in the 1950's and 1960's, but today the manatee is protected by law as an endangered species. However, manatees still face several dangers, such as illegal fishing nets, injuries from motorboats, and habitat loss. Due to their low reproductive rates, the decline in manatee populations may be hard to reverse in the coming years.

West Indian Manatees in Pictures