Habitat: Coastal shallows, estuaries and rivers (can occupy both saltwater and freshwater).
Geographical spread: Southeastern N America (Florida), Caribbean and northern S America or Atlantic coast to central Brazil.
Current population: 2,600 around Florida (New Scientist, This Week 20.4.96).
Status: Considered vulnerable by the IUCN and are protected under the CITES.
Size: Head to tail length 3.7-4.6m.
Weight: 1,600kg.
Average life expectancy: 40 years in captivity but probably 50-60 years in the wild.
Normal diet: The West Indian Manatee is a herbivore and spends the majority of its time feeding. It feeds on floating or submerged sea grasses which grow in relatively clear marine water and will also enter inland waterways, rivers and lakes to fe ed on freshwater plants. May eat algae but it is not an important part of the diet. They are non-ruminant herbivores (like horses and elephants but unlike cows and sheep) who have few competitors for food.
Normal lifestyle: The West Indian Manatee is slow-moving, long-lived and with a low reproductive capacity. Does not form cohesive social groups but can be found in unorganised groups at warm water sources in winter or during mating activities. May form transient associations on summer ranges which may be important in establishing movement patterns that later become habitual. Manatees not only make extensive seasonal movements, they also travel long distances within seasons. Receptive females attr act herds of 5-17 males that escort and try to mate with her. Manatees do not have the elaborate courtship displays characteristic of territorial mammals. Females give birth to a single young which stays with her until it is 1-2 years old. During this pe riod the calf learns migration routes, foods and preferred feeding areas from its mother. Sexual maturity occurs between the ages of 4 and 8.
Reasons for decline: Threatened by historical and modern overhunting. They are hunted for their meat, oil for cooking and tough hide. Nowadays collisions with boats constitute the largest identifiable source of mortality. There is abundant boat tr affic in Florida and about 65% of manatee deaths in a year result from collisions with boats (BBC Wildlife, Aug 1986). Boat traffic also interferes with mating activities and causes sound pollution disrupts communication by vocal signals. They are also l osing habitat as a result of coastal development. Since 5 March 1996 131 manatees have washed up dead on Florida's beaches. The cause of death is pneumonia which appears to have resulted from dense concentrations of the dinoflagellate Ptychodiscus brevis (a red tide). It produces a deadly toxin that affects the respiratory systems of fish.and other marine animals. The number dead has now increased to 155 (BBC Wildlife June 1996).
Conservation projects: In Florida a public awareness campaign has been launched. Signs and posters have been put up to warn boaters about the presence of manatees. Manatee-proof flood control structures have also been developed and the manatee has been named the official marine mammal of the state of Florida.
Special effects: This species is often divided into 2 subspecies, the Florida manatee (T. m. Iatirostris) and the Antillean manatee (T. m. manatus). Steller's sea cow (Hydrodamalis gigas) was a fifth species of sirenian. It was the largest species and was a specialist feeder on kelp (dense marine algae). It was exterminated by man in 1768.
File last modified Thursday, October 3, 1996