The Amazonian manatee is an aquatic mammal with a bizarre appearance, first described as follows: a curious combination of a seal and a hippopotamus. They also have the name ‘seacow’ and come from the ‘Sirenia’ order. Living just in bodies of freshwater, these manatees are typically found in lagoons and lakes, often off the branches of bigger rivers. This enables them to travel back and forth between access points when they are in need of a good supply of plant life to eat. The Amazonian manatee has been sighted in all parts of the Amazon River Basin. In the wild these animals live for up to 30 years and in captivity around 12.5 years.
Amazonian manatees occur throughout the Amazon Basin in northern South America (Colombia, Ecuador, Peru and Brazil). They only live in freshwater and they prefer oxbows, blackwater lakes, and lagoons which have deep connections to big rivers and plenty of aquatic vegetation.
Amazonian manatees are gregarious animals and used to occur in big herds. Due to severe overhunting, however, groups seen today number only 4 to 8 individuals. These manatees are both nocturnal and diurnal and they live their lives almost entirely underwater. Only their nostrils stick up above the water as they search the bottoms of rivers and lakes for lush vegetation. An individual in one day can eat as much as eight percent of its body weight of aquatic vegetation. Feeding mostly takes place in the wet season, when these animals graze on new plants in backwaters that are flooded seasonally. When the manatees return during the dry season to the primary water courses, for weeks they may not eat.
As herbivorous species, the Amazonian manatee eats aquatic vegetation like grasses, water hyacinths and water lettuce (pisitia). It will also eat floating palm fruits. Individuals in captivity are able to eat 9 to 15 kilograms per day of leafy vegetables.
Mating herds form that consist of a male and a few females. The females have the freedom to leave their herd and so may mate with another male, meaning that Amazonian manatees may have a polyandrous mating system. Breeding can take place throughout the year, with peaks occurring at different times in various parts of the system of rivers. In the central Amazon, births mostly occur in February-May, which is when water levels rise. A single young is born after gestation of around one year. Births occur at 2-3 year intervals. Young are very well looked after by their mothers, who will nurse them up to the age of 18 months. Males are 5 to 6 years old when they first mate, and females much younger, with their average age being about 3 years old.
Once occurring in large herds and with healthy population numbers, Amazonian manatee numbers have decreased due to extensive hunting by commercial and subsistence hunters. It has been hunted for meat, fat and oil, and in the past for its hide, for use as machine belts and water hoses. Current threats include hunting and drowning accidentally in commercial fishing nets. Large areas surrounding the manatee’s river habitats being deforested has also caused the soil to erode, as well as degradation of food sources and reduction in vegetation in the waterways.
Although manatees are widespread through a large area, there is a high level of uncertainty about total population size. According to the IUCN Red List resource, a minimum of 10,000 individuals was estimated in 1977 for the Amazon Basin as a whole. Currently Amazonian manatees are classified as Vulnerable (VU) and their numbers today continue to decrease.