01 março 2010
Discover why this docile representative of the Brazilian fauna is threatened with extinction.
The manatees are aquatic mammals of the taxonomic order Sirenia. The name was given because of this animal’s ‘song’ which made early mariners associate them with the mythological ‘sirens’, singing sea creatures resembling women.
There are only four species of manatee in the world and one of them lives exclusively in fresh water, and even more exclusively, in the Brazilian Amazon.
The Amazonian Manatee, Trichechus inunguis, is the smallest of the manatee species and originally inhabited all the rivers of the Amazon and Orinoco basins thus including parts of Colombia and Venezuela. However the animal has been highly sought after by hunters for its abundant meat and oil that can be got from it. Over the years, hunting has severely diminished the populations.
The Amazonian manatee is currently classified as a vulnerable species by the International Union for the Conservation of Nature and is listed by the Brazilian Ministry of the Environment as a species under threat of extinction. In Brazil hunting it has been forbidden since 1973 but because it is such a docile and curious animal, it often comes up close to boat and river traffic and becomes an easy prey for hunters or involves itself in accidents with boats.
Layers of fat
The Amazonian manatee is a herbivorous mammal – that is, it feeds exclusively on algae, aquatic plants and aquatic grasses. Nevertheless, munching away, plant by plant, the manatee can eventually weigh up to 300 kg and be as long as 2.5 metres.
It eats most prodigiously during the rainy season when there is more vegetation available. It may spend as much as eight hours a day grazing and eat the equivalent of 10% of its own bodyweight in a single day. All the food is stored up in the form of fat which supplies its needs during the dry periods when food is scarce.
When the rains are over, the manatee leaves the small creeks and inlets where it normally lives a solitary life and goes out into the big rivers joining others to form groups of four to eight individuals.
When it is not eating...
... the Brazilian manatee will probably be sleeping; it spends more than half of each day sleeping in the water. Because it is a mammal, it needs to breathe at the surface and it usually takes in breath at five minute intervals but when it is sleeping, and very still, it can remain submerged for up to 25 minutes.
While its sea-dwelling cousins, the marine manatee are as much at home in fresh water as sea water, the Amazonian manatee rarely enters salt water areas.
The manatee populations have limited powers of recovery because of their long reproductive cycle. Each female manatee produces only one calf at a time. Twins are very rare and the pregnancy cycle is 13 months long.
After the young manatee is born the mother will suckle it for two years. She is a very attentive mother; she teaches the young one to swim, select the plants to graze on and go up to the surface to breathe. The result of the whole process however is that she will only produce offspring once every four years.
It is that protracted reproductive cycle that makes the conservation of the Amazonian manatee such a daunting challenge. In addition to curbing hunting and diminishing the number of deaths caused by river boat accidents, there is an overwhelming need to invest in the conservation of their habitat, that is: the Amazon.