West Indian manatees are large, gray-brown aquatic mammals with bodies that taper to a flat, paddle- shaped tail. They have two flippers with three to four nails on each, and their head and face are wrinkled with whiskers on the snout. The manatee’s closest relative is the elephant and hyrax (a small furry animal that resembles a rodent).
Manatees are believed to have evolved from a wading, plant-eating animal. The West Indian manatee is related to the West African manatee, the Amazonian manatee, the dugong, and Steller’s sea cow, which was hunted to extinction in 1768. The average adult manatee is about 10 feet long and weighs about 1,000 pounds.
Habitat and Range
Manatees can be found in shallow, slow-moving rivers, estuaries, saltwater bays, canals and coastal areas. Manatees are a migratory species.
Manatees are gentle and slow-moving. Most of their time is spent eating, resting, and in travel. Manatees are completely herbivorous. They eat aquatic plants and can consume 10-15% of their body weight daily in vegetation. They graze for food along water bottoms and on the surface. They may rest submerged at the bottom or just below the surface, coming up to breathe on the average of every three to five minutes. When manatees are using a great deal of energy, they may surface to breathe as often as every 30 seconds.
Lifespan, Mortality, Population
West Indian manatees have no natural enemies, and it is believed they can live 60 years or more. Many manatee mortalities are human-related. Most human-related manatee mortalities occur from collisions with watercraft. Other causes of human-related manatee mortalities include being crushed and/or drowned in canal locks and flood control structures; ingestion of fish hooks, litter and monofilament line; entanglement in crab trap lines; and vandalism. Ultimately, however, loss of habitat is the most serious threat facing manatees today.
Breeding and Reproduction
The reproductive rate for manatees is slow. Female manatees are not sexually mature until five years old, and males are mature around nine years of age. It is believed that one calf is born every
two to five years; twins are rare. The gestation period is approximately 13 months. Mothers nurse their young for a long period and a calf may remain dependent on its mother for up to two years.