African manatee

African manatee
Conservation status
Vulnerable  (IUCN 3.1)
Scientific classification
Missing taxonomy template (fix):	Trichechus senegalensis
Binomial name
Trichechus senegalensis Link, 1795
African manatee range

The African manatee (Trichechus senegalensis), also known as the West African manatee or seacow, is a species of manatee and eats mostly plants. African manatees can be found in much of the western region of Africa, from Senegal to Angola. Scientists do not know a lot about this species, but they hypothesize that the African manatee is very similar to the Indian manatee.

Taxonomy

The African manatee was officially declared a species under the Trichechus senegalensis taxon in 1795 by the naturalist, Johann Heinrich Friedrich Link. There aren't any known subspecies of this taxon, but unreliable claims have been made that there are morphological disparities between coastal manatee populations and populations that have been isolated inland. After more research, it was proven that there is no genetic evidence to support these claims and form any subspecies. The African manatee falls under the Trichechus genus with only two other species, the Amazonian manatee and the West Indian manatee, which are also sirenians.

Range and habitat

African manatee in Toba Aquarium in Toba, Mie, Japan.

African manatees can be found in much of the western region of Africa, such as in the countries of Angola, Benin, Cameroon, Chad, Republic of the Congo, Democratic Republic of the Congo, Côte d'Ivoire, Equatorial Guinea, Gabon, The Gambia, Ghana, Guinea, Guinea-Bissau, Liberia, Mali, Mauritania, Niger, Nigeria, Senegal, Sierra Leone and Togo. Not only are these manatees found in many countries, but also in many different kinds of bodies of water, ranging from brackish to freshwater. They can be found in oceans, rivers, lakes, coastal estuaries, reservoirs, lagoons, and calm shallow bays on the coast. However, a limiting factor of where the African manatee can live is temperature. It is very rare to find an African manatee in water with a temperature below 18 degrees Celsius.

First, some are located along the west coast of Africa in the southeastern and central eastern waters of the Atlantic Ocean. Manatees are found as far offshore as 75 km (47 mi) out, where there are shallow coastal flats and calm mangrove creeks filled with seagrass. Lakes where they dwell include Lake Volta, Inner Niger River Delta in Mali, Lake Léré, and Lake de Tréné. Due to fluctuating flow rates and water levels in rivers, some of these permanent lakes serve as a refuge during the dry season to manatees in connecting rivers. From north to south, the river systems that they can be sited in include the Senegal, Saloum, Gambia, Casamance, Cacheu, Mansôa, Geba, Buba, Tombali, Cacine, Kogon, Kondoure, Sierra Leone, Great Scarcies, Little Scarcies, Sherbro, Malem, Waanje, Sewa, Missunado, Cavalla, St. Paul, Morro, St. John, Bandama, Niouniourou, Sassandra, Comoé, Bia, Tano, Volta, Mono, Oueme, Niger, Mekrou, Benue, Cross, Katsena Ala, Bani, Akwayafe, Rio del Rey, Ngosso, Andokat, Mene, Munaya, Wouri, Sanaga, Faro, Chari, Bamaingui, Bahr-Kieta, Logoné, Mitémélé, Gabon, Ogoué, Lovanzi, Kouilou, Congo, Dande, Bengo, and Cuanza. They go up these rivers until they are unable to progress due to water that is too shallow for them to swim through or strong waterfalls that they cannot pass.

One way that African manatees are like West Indian manatees is that they both need habitats that have protected water with access to food and freshwater. They occasionally journey to less sheltered areas, but this is a rare occurrence. Out of all of their many habitats in Africa, the most populated areas seem to be Guinea-Bissau; the lagoons of Ivory Coast; the southern portions of the Niger River in Nigeria; Sanaga River, Cameroon; coastal lagoons in Gabon; and the lower parts of the Congo River. A study was done in Côte d'Ivoire to find where most African manatees favored living. They were radio-tagged and tracked, and the results were that they were sighted the most in coastal lagoons with plenty of their main food source, mangroves and other herbaceous growths; in grass-lined estuaries of big rivers with plenty of mangroves; and protected coastal spots with less than 3 meters of water, again, with bountiful mangroves and also marine macrophytes.

Diet

Although generally speaking, manatees are herbivores, the African manatee also eats clams, mollusks, and fish that they find in nets. The majority of the diet of the African manatee is composed of many different types of flora found above or hanging over the water, instead of submerged. African manatees inhabiting rivers eat mostly overhanging plants that grow on the river banks. The diet of African manatees living in estuaries consists of just one thing: mangrove trees. Each day, the African manatee will eat approximately 4% to 9% of its body weight in wet vegetation. Microorganisms in the African manatee's long large intestine (which measures up to 20 meters in length) aid the manatee in digesting the large quantity and variety of vegetation that it takes in every day.

Description

African manatee in Toba Aquarium in Toba, Mie, Japan.

The shape of an African manatee's body is such that it is "full around the middle and narrowing to a paddle-shaped tail". The African manatee is gray in color, with small, colorless hairs around its body. However, algae and other tiny organisms often grow on them so that the manatees appear brown or green-ish. Calves, however, are darker in color when they are very young. In length, African manatees measure up to 4.5 meters (approximately 14.6 feet), and they weigh approximately 360 kilograms (790 pounds). African manatees are extremely slow, moving at between 4.8 and 8 kilometers (only 3–5 miles) an hour, unless they fear predators, at which time the manatee can travel at speeds of approximately 32 kilometers (20 miles) an hour. The African manatee's large forelimbs, or flippers, are used to paddle and to bring food to the manatee's mouth, after which the vegetation is chewed by the manatee's strong molars, which are the only teeth the African manatee has. Each jaw has 2 vestigial incisors when the manatee is born, which it loses as it matures. If the African manatee's molars happen to fall out, new molars grow in their place. The manatee's flippers, which bear nails, are also used "to embrace and touch other manatees". The African manatee does not have any hindlimbs. By looking at the exterior of the African manatee, one would not be able to distinguish it from the American manatee. Contrastingly, the exterior of the African manatee differs from that of the last type of manatee, the Amazonian manatee, because the Amazonian manatee has characteristic white markings on its abdomen.

Evolution and Legends

It is believed that a form descendents of "coastal South American trichechids" of the late time of Pliocene "reached West Africa by way of transoceanic currents, perhaps since the late Pliocene, to give rise to the West African manatee."

According to people of western Africa, Maame (also spelled mami) water, a reoccuring character in many coastal legends, is a goddess of the sea, and a symbol of wealth and beauty. Contrasting with this depiction, Maame water also flips over canoes and entices their occupants to come "down to her watery kingdom". "Scientists from the Institute of Aquatic Biology of the Centre for Scientific and Industrial Research (CSIR) and the Wildlife Department in Ghana" have drawn the conclusion that Maame Water is not a sea goddess, in fact, but the West African manatee. According to Dr. Mamaa Entsua-Mensah, who performs research for CSIR, "the female Manatee looks like a woman when they surface to inhale fresh air at night." Entsua-Mensah said "because of the breast with teats, when people sight the mammals jumping out of the sea in the night to take in long deep breath of air, they are perceived as half woman, half fish." It was not allowed to openly speak of the sacred goddess "Maame Water" except after certain rituals. In Nigeria, stories are passed through generations concerning "persons whose fortunes have changed dramatically when they married "Maame Water", the mermaid, but lost everything when they became unfaithful to her".

Behavior

Like many other animals, the African manatee is nocturnal, tending to travel silently, eat, and be active towards the end of the day and the nighttime. During the daytime, the African manatee dozes in shallow (1–2 meters deep) water. In countries such as Sierra Leone, African manatees are known to migrate upstream when flooding occurs in June and July. This flooding can lower the availability of food for the manatees and the salinity of waterways. Research shows that African manatees live in groups of one to six individuals. One reason for the African manatee living in small groups is that it has very few natural predators, two of which are sharks and crocodiles.

Reproduction

One cannot tell the sex of an individual African manatee without closely examining the manatee's underside. The only visible distinctions between males and females are the genital openings. However, males tend to be smaller than females. Some female African manatees are sexually mature after as little as 3 years of age, and they give birth every 3 to 5 years of their estimated 30 year life span. Male African manatees take a much longer time to mature, about 9 to 10 years. Rarely will a male African manatee be able to fertilize an egg at 2 or 3 years of age. African manatees breed at all times of the year. When male and female African manatees mate, it is not for life; multiple males will usually mate with one female. Males fight with each other by pushing and shoving when the opportunity to mate with a female is at stake. Female African manatees give birth to one baby (calf) at a time after being pregnant for approximately 13 months, and calves can swim on their own as soon as they are born. Although the African manatee's social organization is not well known, research has shown that the most common and tightly knit social groups are between a mother and her calf.

Threats

The African manatee has become a vulnerable species because its meat, oil, bones (used to make walking stick handles and "spinning-tops used in a local game called cii"), and skin bring great wealth to poachers. In some countries, such as Nigeria and Camaroon, African manatees are sold to zoos, aquariums, and online as pets, sometimes being shipped internationally. Anyone visiting such countries would easily notice the manatee meat being sold on the streets and marketplaces, but the lack of law enforcement prevents the poachers from being punished. Residents of countries such as Mali and Chad depend on the oil of the African manatee to cure ailments such as ear infections, rheumatism, and skin conditions.

Urban and agricultural development, increased damming, and increased use of hydroelectric power in rivers in countries such as Côte d'Ivoire and Ghana are more threats to the African manatee's habitat and life, and thick congestion of boats in waterways may cause African manatees to have a deadly run-in with the vessels. However, even natural occurrences such as droughts and tidal changes often strand manatees in an unsuitable habitat, and some African manatees are killed accidentally by fishing trawls and nets intended for catching sharks.

Some behaviors of African manatees provoke humans' desires to hunt them. When the African manatees get tangled up in fishing nets, the animals can do damage to the nets. People in countries such as Sierra Leone feel that if they kill and therefore reduce the number of African manatees, the chances of their nets requiring expensive repairs will be lessened. In addition, African manatees have been known to destroy rice crops by drifting into fields during the rainy season, which is another reason for humans to want to kill them.

Conservation

From November 2004 until December 2007, the West African Manatee Conservation Project completed Phase I. During this phase, residents of 6 African countries (Mauritania, Senegal, The Gambia, Guinea, Guinea Bissau and Sierra Leone) put together a database of previously unknown information about the African manatee (such as population, economic value, and habitat range) by conducting surveys in their countries. Other African countries also contributed reports that broadened knowledge of the African manatee. Because of the work done during this phase, the general public, young children, and experienced scientists alike are receiving better information than ever before as to how to protect the African manatees. Phase I also allowed for up close examination of the African manatee's way of life through field work.

Due to the large-scale success of Phase I, a Phase II is to be enacted by Wetlands International. During Phase II, the information collected in Phase I will be even more widely distributed around the areas in which the African manatee lives, and the second phase will focus on "improving legislation and developing research, communication, and education."

"The African manatee is listed on Appendix II of the Convention on International Trade in Endangered Species (CITES)", which states that trade in any species on the list is to be very carefully watched out for and terminated. Also, laws protect the African manatee in every country in which it lives! However, laws will do nothing if they are not enforced, which is unfortunately the case with the African manatee. Due to mass lack of enforcement and education, the African manatee population is still being steadily depleted.