West Indian manatee

Appearance

Like other manatees, the West Indian manatee has adapted fully to an aquatic life style, having no hind limbs. Pelage cover is sparsely distributed across the body, which may play a role in reducing the build-up of algae on their thick skin. The average West Indian manatee is approximately 2.7–3.5 m long and weighs 200–600 kg , with females generally larger than males. The largest individual on record weighed 1,655 kg and measured 4.6 m long. This manatee's color is gray or brown. Its flippers also have either three or four nails, so it can hold its food as it is eating.

Behavior

The West Indian manatee is surprisingly agile in water, and individuals have been seen doing rolls, somersaults, and even swimming upside-down. Manatees are not territorial and do not have complex predator avoidance behavior, as they have evolved in areas without natural predators. The common predators of marine mammals, such as orcas and large sharks, are rarely found in habitats inhabited by this species.

The West Indian manatee is an opportunistic feeder, with large adults consuming 10% to 15% of their body weight in food daily. Manatees feed on about 60 plant species, which includes sea grasses as their major food source. They also consume some fish and small invertebrates. Because manatees feed on abrasive plants, their molars are often worn down and are continually replaced throughout life, called "marching molars".

The West Indian manatee has a high casualty rate due to thermal shock from cold temperatures. During cold weather, many die due to their digestive tracts shutting down at water temperatures below 68°F . Many manatee deaths are caused by large commercial vessels, but are attributed to "recreational watercraft" due to the elimination of that classification.

Habitat

As its name implies, the West Indian manatee lives in the West Indies, or Caribbean, generally in shallow coastal areas. However, it is known to withstand large changes in water salinity, so has also been found in shallow rivers and estuaries. It can live in fresh water, saline water, and even brackish water. It is limited to the tropics and subtropics due to an extremely low metabolic rate and lack of a thick layer of insulating body fat. While this is a regularly occurring species along coastal southern Florida, during summer, this large mammal has even been found as far north as Dennis, Massachusetts and as far west as Texas.

The Florida manatee , a subspecies of the West Indian manatee, is the largest of all living sirenians. Florida manatees inhabit the most northern limit of sirenian habitat. Over three decades of research by universities, governmental agencies, and NGOs, has contributed to our understanding of Florida manatee ecology and behavior, which is more than we know about any other sirenian species. They are found in freshwater rivers, in estuaries, and in the coastal waters of the Gulf of Mexico and the Atlantic Ocean. Florida manatees may live to be greater than 60 years old in the wild, and one captive manatee, "Snooty", has lived for 63 years. In captivity, West Indian manatees live up to 28 years. The biggest single threat to Florida manatees is death from collisions with recreational watercraft. Large concentrations of Florida manatees are located in the Crystal River area and the Wakulla Springs regions in central and north Florida. The best time to see the Wakulla Springs manatees is in November and December, and in the spring for the Crystal River manatees.

The other subspecies of the West Indian manatee is sometimes referred to as the Antillean manatee . Antillean manatees are sparsely distributed throughout the Caribbean and the northwestern Atlantic Ocean, from Mexico, east to the Greater Antilles, and south to Brazil. They are found in French Guiana, Suriname, Guyana, Trinidad , Venezuela, Colombia, Panama, Costa Rica, Nicaragua, Honduras, Guatemala, Belize, Mexico, Trinidad, Cuba, Haiti, the Dominican Republic, Jamaica, and Puerto Rico. Historically, Antillean manatees were hunted by local natives and sold to European explorers for food. Today, they are threatened by loss of habitat, poaching, entanglement with fishing gear, and increased boating activity. Several of Sirenian International's scientists study Antillean manatees in Belize, which may be the last stronghold for the subspecies. Funds for research, education, and conservation projects are desperately needed in other Central American nations.

Reproduction

Although female West Indian manatees are mostly solitary creatures, they form mating herds while in estrus. Most females first breed successfully between ages of seven and nine; they are, however, capable of reproduction as early as four years of age. The gestation period lasts from 12 to 14 months. Normally, one calf is born, although on rare occasions two have been recorded. The young are born with molars, allowing them to consume sea grass within the first three weeks of birth. On average, manatees that survive to adulthood will have between five and seven offspring between the ages of 20 and 26.
When a calf is born, it usually weighs between 60 and 70 pounds and is between 4.0 and 4.5 feet long. The family unit consists of mother and calf, which remain together for up to two years. Males aggregate in mating herds around a female when she is ready to mate, but contribute no parental care to the calf.

Food

The West Indian manatee is surprisingly agile in water, and individuals have been seen doing rolls, somersaults, and even swimming upside-down. Manatees are not territorial and do not have complex predator avoidance behavior, as they have evolved in areas without natural predators. The common predators of marine mammals, such as orcas and large sharks, are rarely found in habitats inhabited by this species.

The West Indian manatee is an opportunistic feeder, with large adults consuming 10% to 15% of their body weight in food daily. Manatees feed on about 60 plant species, which includes sea grasses as their major food source. They also consume some fish and small invertebrates. Because manatees feed on abrasive plants, their molars are often worn down and are continually replaced throughout life, called "marching molars".

The West Indian manatee has a high casualty rate due to thermal shock from cold temperatures. During cold weather, many die due to their digestive tracts shutting down at water temperatures below 68°F . Many manatee deaths are caused by large commercial vessels, but are attributed to "recreational watercraft" due to the elimination of that classification.