Manatee
Overview
Manatees are large, fully aquatic, mostly herbivorous marine mammal
Marine mammal
Marine mammals, which include seals, whales, dolphins, and walruses, form a diverse group of 128 species that rely on the ocean for their existence. They do not represent a distinct biological grouping, but rather are unified by their reliance on the marine environment for feeding. The level of...

s sometimes known as sea cows. There are three accepted living species of Trichechidae, representing three of the four living species in the order Sirenia
Sirenia
Sirenia is an order of fully aquatic, herbivorous mammals that inhabit swamps, rivers, estuaries, marine wetlands, and coastal marine waters. Four species are living, in two families and genera. These are the dugong and manatees...

: the Amazonian manatee
Amazonian Manatee
The Amazonian Manatee is a species of manatee that lives in the freshwater habitats of the Amazon basin. They are found in Brazil, Peru, Colombia, Ecuador, Guyana and Venezuela. Amazonian manatees are aquatic animals of the Sirenia order and are also known as "seacows". Their colour is grey but...

 (Trichechus inunguis), the West Indian manatee
West Indian Manatee
The West Indian Manatee is a manatee, and the largest surviving member of the aquatic mammal order Sirenia . The West Indian Manatee, Trichechus manatus, is a species distinct from the Amazonian Manatee, T. inunguis, and the West African Manatee, T. senegalensis...

 (Trichechus manatus), and the West African manatee (Trichechus senegalensis). They measure up to 13 feet (4 m) long, weigh as much as 1300 pounds (589.7 kg), and have paddle-like flippers.
Encyclopedia
Manatees are large, fully aquatic, mostly herbivorous marine mammal
Marine mammal
Marine mammals, which include seals, whales, dolphins, and walruses, form a diverse group of 128 species that rely on the ocean for their existence. They do not represent a distinct biological grouping, but rather are unified by their reliance on the marine environment for feeding. The level of...

s sometimes known as sea cows. There are three accepted living species of Trichechidae, representing three of the four living species in the order Sirenia
Sirenia
Sirenia is an order of fully aquatic, herbivorous mammals that inhabit swamps, rivers, estuaries, marine wetlands, and coastal marine waters. Four species are living, in two families and genera. These are the dugong and manatees...

: the Amazonian manatee
Amazonian Manatee
The Amazonian Manatee is a species of manatee that lives in the freshwater habitats of the Amazon basin. They are found in Brazil, Peru, Colombia, Ecuador, Guyana and Venezuela. Amazonian manatees are aquatic animals of the Sirenia order and are also known as "seacows". Their colour is grey but...

 (Trichechus inunguis), the West Indian manatee
West Indian Manatee
The West Indian Manatee is a manatee, and the largest surviving member of the aquatic mammal order Sirenia . The West Indian Manatee, Trichechus manatus, is a species distinct from the Amazonian Manatee, T. inunguis, and the West African Manatee, T. senegalensis...

 (Trichechus manatus), and the West African manatee (Trichechus senegalensis). They measure up to 13 feet (4 m) long, weigh as much as 1300 pounds (589.7 kg), and have paddle-like flippers. The name manatí comes from the Taíno
Taíno people
The Taínos were pre-Columbian inhabitants of the Bahamas, Greater Antilles, and the northern Lesser Antilles. It is thought that the seafaring Taínos are relatives of the Arawak people of South America...

, a pre-Columbian
Pre-Columbian
The pre-Columbian era incorporates all period subdivisions in the history and prehistory of the Americas before the appearance of significant European influences on the American continents, spanning the time of the original settlement in the Upper Paleolithic period to European colonization during...

 people of the Caribbean
Caribbean
The Caribbean is a crescent-shaped group of islands more than 2,000 miles long separating the Gulf of Mexico and the Caribbean Sea, to the west and south, from the Atlantic Ocean, to the east and north...

, meaning "breast".

Taxonomy

Manatees comprise three of the four living species in the order Sirenia
Sirenia
Sirenia is an order of fully aquatic, herbivorous mammals that inhabit swamps, rivers, estuaries, marine wetlands, and coastal marine waters. Four species are living, in two families and genera. These are the dugong and manatees...

. The fourth is the Eastern Hemisphere
Eastern Hemisphere
The Eastern Hemisphere, also Eastern hemisphere or eastern hemisphere, is a geographical term for the half of the Earth that is east of the Prime Meridian and west of 180° longitude. It is also used to refer to Europe, Asia, Africa, and Australasia, vis-à-vis the Western Hemisphere, which includes...

's dugong
Dugong
The dugong is a large marine mammal which, together with the manatees, is one of four living species of the order Sirenia. It is the only living representative of the once-diverse family Dugongidae; its closest modern relative, Steller's sea cow , was hunted to extinction in the 18th century...

. The Sirenia are thought to have evolved from four-legged land mammals over 60 million years ago, with the closest living relatives being the Proboscidea
Proboscidea
Proboscidea is a taxonomic order containing one living family, Elephantidae, and several extinct families. This order was first described by J. Illiger in 1881 and encompasses the trunked mammals...

 (elephant
Elephant
Elephants are large land mammals in two extant genera of the family Elephantidae: Elephas and Loxodonta, with the third genus Mammuthus extinct...

s) and Hyracoidea (hyrax
Hyrax
A hyrax is any of four species of fairly small, thickset, herbivorous mammals in the order Hyracoidea. The rock hyrax Procavia capensis, the yellow-spotted rock hyrax Heterohyrax brucei, the western tree hyrax Dendrohyrax dorsalis, and the southern tree hyrax, Dendrohyrax arboreus live in Africa...

es).

The Amazonian's hair color is brownish gray and they have thick, wrinkled skin, often with coarse hair, or "whiskers". Photos are rare; although very little is known about this species, scientists think they are similar to West Indian manatees. The name in Songhay
Songhay languages
The Songhay, Songhai, or Songai languages are a group of closely related languages/dialects centered on the middle stretches of the Niger River in the west African states of Mali, Niger, Benin, Burkina Faso, and Nigeria. They have been widely used as a lingua franca in that region ever since the...

, the local language, is ayyu.

Description

Manatees have a mass of 400 to 550 kg (881.8 to 1,212.5 lb), and mean length of 2.8 to 3 m (9.2 to 9.8 ft), with maxima of 3.6 metres (11.8 ft) and 1775 kilograms (3,913.2 lb) seen (the females tend to be larger and heavier). When born, baby manatees have an average mass of 30 kilograms (66.1 lb). They have a large, flexible, prehensile
Prehensility
Prehensility is the quality of an appendage or organ that has adapted for grasping or holding. The word is derived from the Latin term prehendere, meaning "to grasp."-Examples:Appendages that can become prehensile include:...

 upper lip. They use the lip to gather food and eat, as well as using it for social interactions and communications. Manatees have shorter snouts than their fellow sirenia
Sirenia
Sirenia is an order of fully aquatic, herbivorous mammals that inhabit swamps, rivers, estuaries, marine wetlands, and coastal marine waters. Four species are living, in two families and genera. These are the dugong and manatees...

ns, the dugong
Dugong
The dugong is a large marine mammal which, together with the manatees, is one of four living species of the order Sirenia. It is the only living representative of the once-diverse family Dugongidae; its closest modern relative, Steller's sea cow , was hunted to extinction in the 18th century...

s. Their small, widely-spaced eyes have eyelids that close in a circular manner. The adults have no incisor
Incisor
Incisors are the first kind of tooth in heterodont mammals. They are located in the premaxilla above and mandible below.-Function:...

 or canine
Canine tooth
In mammalian oral anatomy, the canine teeth, also called cuspids, dogteeth, fangs, or eye teeth, are relatively long, pointed teeth...

 teeth, just a set of cheek teeth, which are not clearly differentiated into molar
Molar (tooth)
Molars are the rearmost and most complicated kind of tooth in most mammals. In many mammals they grind food; hence the Latin name mola, "millstone"....

s and premolar
Premolar
The premolar teeth or bicuspids are transitional teeth located between the canine and molar teeth. In humans, there are two premolars per quadrant, making eight premolars total in the mouth. They have at least two cusps. Premolars can be considered as a 'transitional tooth' during chewing, or...

s. Uniquely among mammals, these teeth are continuously replaced throughout life
Polyphydont
A polyphyodont is an animal whose teeth are continuously replaced. Most toothed fishes are polyphyodonts. Diphyodonts, on the other hand, are characterized by having only two successive sets of teeth. Reptiles and most other vertebrates are also polyphyodonts, mammals being the main exception....

, with new teeth growing at the rear as older teeth fall out from farther forward in the mouth. At any given time, a manatee typically has no more than six teeth in each jaw of its mouth. Its tail is paddle-shaped, and is the clearest visible difference between manatees and dugongs; a dugong tail is fluked, similar in shape to a that of a whale.

Like horse
Horse
The horse is one of two extant subspecies of Equus ferus, or the wild horse. It is a single-hooved mammal belonging to the taxonomic family Equidae. The horse has evolved over the past 45 to 55 million years from a small multi-toed creature into the large, single-toed animal of today...

s, they have a simple stomach, but a large cecum
Cecum
The cecum or caecum is a pouch, connecting the ileum with the ascending colon of the large intestine. It is separated from the ileum by the ileocecal valve or Bauhin's valve, and is considered to be the beginning of the large intestine. It is also separated from the colon by the cecocolic...

, in which they can digest tough plant matter. In general, their intestines have a typical length of about 45 meters, which are unusually long for animals of their size.

Life history

Half a manatee's day is spent sleeping in the water, surfacing for air regularly at intervals no greater than 20 minutes. Manatees spend most of the rest of the time grazing in shallow waters at depths of 1–2 m (3.3–6.6 ft). The Florida subspecies (T. m. latirostris) has been known to live up to 60 years.

Swimming

On average, manatees swim at about 5 to 8 km/h (3.1 to 5 mph). However, they have been known to swim at up to 30 kilometres per hour (18.6 mph) in short bursts.

Intelligence

Manatees are capable of understanding discrimination tasks, and show signs of complex associated learning and advanced long term memory. They demonstrate complex discrimination and task-learning similar to dolphin
Dolphin
Dolphins are marine mammals that are closely related to whales and porpoises. There are almost forty species of dolphin in 17 genera. They vary in size from and , up to and . They are found worldwide, mostly in the shallower seas of the continental shelves, and are carnivores, mostly eating...

s and pinniped
Pinniped
Pinnipeds or fin-footed mammals are a widely distributed and diverse group of semiaquatic marine mammals comprising the families Odobenidae , Otariidae , and Phocidae .-Overview: Pinnipeds are typically sleek-bodied and barrel-shaped...

s in acoustic
Acoustics
Acoustics is the interdisciplinary science that deals with the study of all mechanical waves in gases, liquids, and solids including vibration, sound, ultrasound and infrasound. A scientist who works in the field of acoustics is an acoustician while someone working in the field of acoustics...

 and visual studies.

Reproduction

Manatees typically breed once every two years, gestation
Gestation
Gestation is the carrying of an embryo or fetus inside a female viviparous animal. Mammals during pregnancy can have one or more gestations at the same time ....

 lasts about 12 months, and it takes a further 12 to 18 months to wean
Weaning
Weaning is the process of gradually introducing a mammal infant, either human or animal, to what will be its adult diet and withdrawing the supply of its mother's milk.The process takes place only in mammals, as only mammals produce milk...

 the calf. Only a single calf is born at a time and aside from mothers with their young or males following a receptive female, manatees are generally solitary creatures.

Range and habitat

Manatees inhabit the shallow, marsh
Marsh
In geography, a marsh, or morass, is a type of wetland that is subject to frequent or continuous flood. Typically the water is shallow and features grasses, rushes, reeds, typhas, sedges, other herbaceous plants, and moss....

y coastal areas and rivers of the Caribbean Sea
Caribbean Sea
The Caribbean Sea is a sea of the Atlantic Ocean located in the tropics of the Western hemisphere. It is bounded by Mexico and Central America to the west and southwest, to the north by the Greater Antilles, and to the east by the Lesser Antilles....

 and the Gulf of Mexico
Gulf of Mexico
The Gulf of Mexico is a partially landlocked ocean basin largely surrounded by the North American continent and the island of Cuba. It is bounded on the northeast, north and northwest by the Gulf Coast of the United States, on the southwest and south by Mexico, and on the southeast by Cuba. In...

 (T. manatus, West Indian manatee
West Indian Manatee
The West Indian Manatee is a manatee, and the largest surviving member of the aquatic mammal order Sirenia . The West Indian Manatee, Trichechus manatus, is a species distinct from the Amazonian Manatee, T. inunguis, and the West African Manatee, T. senegalensis...

), the Amazon Basin
Amazon Basin
The Amazon Basin is the part of South America drained by the Amazon River and its tributaries that drains an area of about , or roughly 40 percent of South America. The basin is located in the countries of Bolivia, Brazil, Colombia, Ecuador, Guyana, Peru, and Venezuela...

 (T. inunguis, Amazonian manatee
Amazonian Manatee
The Amazonian Manatee is a species of manatee that lives in the freshwater habitats of the Amazon basin. They are found in Brazil, Peru, Colombia, Ecuador, Guyana and Venezuela. Amazonian manatees are aquatic animals of the Sirenia order and are also known as "seacows". Their colour is grey but...

), and West Africa
West Africa
West Africa or Western Africa is the westernmost region of the African continent. Geopolitically, the UN definition of Western Africa includes the following 16 countries and an area of approximately 5 million square km:-Flags of West Africa:...

 (T. senegalensis, West African manatee).

West Indian manatees enjoy warmer waters and are known to congregate in shallow waters, and frequently migrate through brackish water
Brackish water
Brackish water is water that has more salinity than fresh water, but not as much as seawater. It may result from mixing of seawater with fresh water, as in estuaries, or it may occur in brackish fossil aquifers. The word comes from the Middle Dutch root "brak," meaning "salty"...

 estuaries
Estuary
An estuary is a partly enclosed coastal body of water with one or more rivers or streams flowing into it, and with a free connection to the open sea....

 to freshwater
Freshwater
Fresh water is naturally occurring water on the Earth's surface in ice sheets, ice caps, glaciers, bogs, ponds, lakes, rivers and streams, and underground as groundwater in aquifers and underground streams. Fresh water is generally characterized by having low concentrations of dissolved salts and...

 springs
Spring (hydrosphere)
A spring—also known as a rising or resurgence—is a component of the hydrosphere. Specifically, it is any natural situation where water flows to the surface of the earth from underground...

. They cannot survive below 15°C (60°F). Their natural source for warmth during winter is warm, spring-fed rivers.

West Indian

The coast of Georgia is usually the northernmost range of the West Indian manatees because their low metabolic rate does not protect them in cold water. Prolonged exposure to water temperatures below 68 °F (20 °C) can bring about "cold stress syndrome" and death.

Florida manatees can move freely between salinity
Salinity
Salinity is the saltiness or dissolved salt content of a body of water. It is a general term used to describe the levels of different salts such as sodium chloride, magnesium and calcium sulfates, and bicarbonates...

 extremes.

Manatees have been spotted as far north as Cape Cod
Cape Cod
Cape Cod, often referred to locally as simply the Cape, is a cape in the easternmost portion of the state of Massachusetts, in the Northeastern United States...

, and as recently as the late summer of 2006, one was seen in New York City and Rhode Island
Rhode Island
The state of Rhode Island and Providence Plantations, more commonly referred to as Rhode Island , is a state in the New England region of the United States. It is the smallest U.S. state by area...

's Narragansett Bay
Narragansett Bay
Narragansett Bay is a bay and estuary on the north side of Rhode Island Sound. Covering 147 mi2 , the Bay forms New England's largest estuary, which functions as an expansive natural harbor, and includes a small archipelago...

, as cited in The Boston Globe
The Boston Globe
The Boston Globe is an American daily newspaper based in Boston, Massachusetts. The Boston Globe has been owned by The New York Times Company since 1993...

. According to Memphis, Tennessee
Memphis, Tennessee
Memphis is a city in the southwestern corner of the U.S. state of Tennessee, and the county seat of Shelby County. The city is located on the 4th Chickasaw Bluff, south of the confluence of the Wolf and Mississippi rivers....

's The Commercial Appeal
The Commercial Appeal
The Commercial Appeal is the predominant daily newspaper of Memphis, Tennessee, and its surrounding metropolitan area. It is owned by The E. W. Scripps Company, a major North American media company. Scripps also owned the former afternoon paper, the Memphis Press-Scimitar, which it folded in...

newspaper, one manatee was spotted in the Wolf River
Wolf River (Tennessee)
The Wolf River is a alluvial stream in western Tennessee and northern Mississippi, whose confluence with the Mississippi River was the site of various Chickasaw, French, Spanish and American communities and forts that eventually became Memphis, Tennessee....

 harbor near the Mississippi River
Mississippi River
The Mississippi River is the largest river system in North America. Flowing entirely in the United States, this river rises in western Minnesota and meanders slowly southwards for to the Mississippi River Delta at the Gulf of Mexico. With its many tributaries, the Mississippi's watershed drains...

 in downtown Memphis, Tennessee
Memphis, Tennessee
Memphis is a city in the southwestern corner of the U.S. state of Tennessee, and the county seat of Shelby County. The city is located on the 4th Chickasaw Bluff, south of the confluence of the Wolf and Mississippi rivers....

, on October 23, 2006, though it was later found dead ten miles downriver in McKellar Lake.

The West Indian manatee migrates into Florida rivers, such as the Crystal
Crystal River (Florida)
The Crystal River is a very short river in Citrus County, Florida flowing into the Gulf of Mexico. It is just seven miles long, and has a drainage basin of five square miles , joining Kings Bay to the Gulf of Mexico...

, the Homosassa
Homosassa River
Homosassa River is a river in Citrus County, Florida, in the western part of the state. Its headwaters are the Homosassa Springs, and from there it flows west into the Gulf of Mexico...

, and the Chassahowitzka River
Chassahowitzka River
The Chassahowitzka River is a pristine spring-fed river located in southwestern Citrus County, Florida. The river is home to hundreds of species of birds including the Bald Eagle, and is a common refuge for the West Indian Manatee. In 1941, approximately of its saltwater creeks, freshwater...

s. The headsprings of these rivers maintain a 22°C (72°F) temperature year round. During November to March, approximately 400 West Indian manatees (according to the National Wildlife Refuge
National Wildlife Refuge
National Wildlife Refuge is a designation for certain protected areas of the United States managed by the United States Fish and Wildlife Service. The National Wildlife Refuge System is the world's premiere system of public lands and waters set aside to conserve America's fish, wildlife and plants...

) congregate in the rivers in Citrus County, Florida
Citrus County, Florida
Citrus County is a county located in the U.S. state of Florida. As of 2000, the population was 118,085. The U.S. Census Bureau 2008 estimate for the county was 141,416 . Its county seat is Inverness, Florida...

.

During the winter months, manatees often congregate near the warm water outflows of power plants along the coast of Florida instead of migrating south as they once did, causing some conservations to worry they have become too reliant on these artificially-warmed areas. The U.S. Fish and Wildlife Service is trying to find a new way to heat the water for manatees that are dependent on plants that have closed. The main water treatment plant in Guyana
Guyana
Guyana , officially the Co-operative Republic of Guyana, previously the colony of British Guiana, is a sovereign state on the northern coast of South America that is culturally part of the Anglophone Caribbean. Guyana was a former colony of the Dutch and of the British...

 has four manatees that keep storage canals clear of weeds; there are also some in the ponds of the National Park in Georgetown, Guyana
Georgetown, Guyana
Georgetown, estimated population 239,227 , is the capital and largest city of Guyana, located in the Demerara-Mahaica region. It is situated on the Atlantic Ocean coast at the mouth of the Demerara River and it was nicknamed 'Garden City of the Caribbean.' Georgetown is located at . The city serves...

.

Studies suggest Florida manatees must have some access to fresh water for proper osmoregulation
Osmoregulation
Osmoregulation is the active regulation of the osmotic pressure of an organism's fluids to maintain the homeostasis of the organism's water content; that is it keeps the organism's fluids from becoming too diluted or too concentrated. Osmotic pressure is a measure of the tendency of water to move...

.

Accurate population estimates of the Florida manatee (T. manatus) are notoriously difficult and have been called scientifically weak; with widely varying counts from year to year, some areas show increases and others decreases, with very little strong evidence of increases except in two areas. Manatee counts are highly variable without an accurate way to estimate numbers:in Florida in 1996, a winter survey found 2,639 manatees; in 1997, a January survey found 2,229; and a February survey found 1,706. A statewide synoptic survey in January 2010 found 5,067 manatees living in Florida, which is a new record count.

Population viability
Population viability analysis
Population viability analysis is a species-specific method of risk assessment frequently used in conservation biology.It is traditionally defined as the process that determines the probability that a population will go extinct within a given number of years.More recently, PVA has been described...

 studies carried out in 1997 found that decreasing adult survival and eventual extinction is a probable future outcome for Florida manatees, without additional protection.

Fossil remains of Florida manatee ancestors date back about 45 million years.

Amazonian

The freshwater Amazonian manatee (T. inunguis) inhabits the Amazon River and its tributaries, and never ventures into salt water.

West African

They are found in coastal marine and estuarine habitats, and in freshwater river systems along the west coast of Africa from the Senegal River
Sénégal River
The Sénégal River is a long river in West Africa that forms the border between Senegal and Mauritania.The Sénégal's headwaters are the Semefé and Bafing rivers which both originate in Guinea; they form a small part of the Guinean-Malian border before coming together at Bafoulabé in Mali...

 south to the Kwanza River in Angola
Angola
Angola, officially the Republic of Angola , is a country in south-central Africa bordered by Namibia on the south, the Democratic Republic of the Congo on the north, and Zambia on the east; its west coast is on the Atlantic Ocean with Luanda as its capital city...

, including areas in Gambia, Liberia
Liberia
Liberia , officially the Republic of Liberia, is a country in West Africa. It is bordered by Sierra Leone on the west, Guinea on the north and Côte d'Ivoire on the east. Liberia's coastline is composed of mostly mangrove forests while the more sparsely populated inland consists of forests that open...

, Guinea-Bissau
Guinea-Bissau
The Republic of Guinea-Bissau is a country in West Africa. It is bordered by Senegal to the north, and Guinea to the south and east, with the Atlantic Ocean to its west....

, Guinea
Guinea
Guinea , officially the Republic of Guinea , is a country in West Africa. Formerly known as French Guinea , it is today sometimes called Guinea-Conakry to distinguish it from its neighbour Guinea-Bissau. Guinea is divided into eight administrative regions and subdivided into thirty-three prefectures...

, Sierra Leone
Sierra Leone
Sierra Leone , officially the Republic of Sierra Leone, is a country in West Africa. It is bordered by Guinea to the north and east, Liberia to the southeast, and the Atlantic Ocean to the west and southwest. Sierra Leone covers a total area of and has an estimated population between 5.4 and 6.4...

, Côte d'Ivoire
Côte d'Ivoire
The Republic of Côte d'Ivoire or Ivory Coast is a country in West Africa. It has an area of , and borders the countries Liberia, Guinea, Mali, Burkina Faso and Ghana; its southern boundary is along the Gulf of Guinea. The country's population was 15,366,672 in 1998 and was estimated to be...

, Ghana
Ghana
Ghana , officially the Republic of Ghana, is a country located in West Africa. It is bordered by Côte d'Ivoire to the west, Burkina Faso to the north, Togo to the east, and the Gulf of Guinea to the south...

, Mali
Mali
Mali , officially the Republic of Mali , is a landlocked country in Western Africa. Mali borders Algeria on the north, Niger on the east, Burkina Faso and the Côte d'Ivoire on the south, Guinea on the south-west, and Senegal and Mauritania on the west. Its size is just over 1,240,000 km² with...

, Nigeria
Nigeria
Nigeria , officially the Federal Republic of Nigeria, is a federal constitutional republic comprising 36 states and its Federal Capital Territory, Abuja. The country is located in West Africa and shares land borders with the Republic of Benin in the west, Chad and Cameroon in the east, and Niger in...

, Cameroon
Cameroon
Cameroon, officially the Republic of Cameroon , is a country in west Central Africa. It is bordered by Nigeria to the west; Chad to the northeast; the Central African Republic to the east; and Equatorial Guinea, Gabon, and the Republic of the Congo to the south. Cameroon's coastline lies on the...

, Gabon
Gabon
Gabon , officially the Gabonese Republic is a state in west central Africa sharing borders with Equatorial Guinea to the northwest, Cameroon to the north, and with the Republic of the Congo curving around the east and south. The Gulf of Guinea, an arm of the Atlantic Ocean is to the west...

, Republic of the Congo
Republic of the Congo
The Republic of the Congo , sometimes known locally as Congo-Brazzaville, is a state in Central Africa. It is bordered by Gabon, Cameroon, the Central African Republic, the Democratic Republic of the Congo , the Angolan exclave province of Cabinda, and the Gulf of Guinea.The region was dominated by...

, and Democratic Republic of the Congo
Democratic Republic of the Congo
The Democratic Republic of the Congo is a state located in Central Africa. It is the second largest country in Africa by area and the eleventh largest in the world...

.

They live as far upriver on the Niger River
Niger River
The Niger River is the principal river of western Africa, extending about . Its drainage basin is in area. Its source is in the Guinea Highlands in southeastern Guinea...

 as Gao, Mali.

Communication

They emit a wide range of sounds used in communication, especially between cows and their calves. Adults communicate to maintain contact and during sexual and play behaviors. Taste and smell, in addition to sight, sound, and touch, may also be forms of communication.

Diet

Manatees are herbivores and eat over 60 different plant species, such as mangrove
Mangrove
Mangroves are various kinds of trees up to medium height and shrubs that grow in saline coastal sediment habitats in the tropics and subtropics – mainly between latitudes N and S...

 leaves, turtle grass
Seagrass
Seagrasses are flowering plants from one of four plant families , all in the order Alismatales , which grow in marine, fully saline environments.-Ecology:...

, and types of algae. Using its divided upper lip, an adult manatee will commonly eat up to 10% of its body weight (about 50 kg) per day. Manatees have been known to eat small amounts of fish from nets.

Predation

Manatees have few natural predators. Nevertheless, shark
Shark
Sharks are a type of fish with a full cartilaginous skeleton and a highly streamlined body. The earliest known sharks date from more than 420 million years ago....

s, crocodile
Crocodile
A crocodile is any species belonging to the family Crocodylidae . The term can also be used more loosely to include all extant members of the order Crocodilia: i.e...

s and alligator
Alligator
An alligator is a crocodilian in the genus Alligator of the family Alligatoridae. There are two extant alligator species: the American alligator and the Chinese alligator ....

s have been known to prey on manatees from time to time. Overall, however, predation does not present a significant threat to the survival of any manatee species.

Relation to humans

Threats

The main causes of death for the sea cows are human-related issues, such as habitat destruction and human objects, and natural causes, such as temperatures and disease.

Ship strikes

Their slow-moving, curious nature, coupled with dense coastal development, has led to many violent collisions with propeller-driven boats and ships, leading frequently to maiming, disfigurement, and even death. As a result, a large proportion of manatees exhibit spiral cutting propeller scars on their backs, usually caused by larger vessels that do not have skegs in front of the propellers like the smaller outboard and inboard-outboard recreational boats have.. They are now even identified by humans based on their scar patterns. Many manatees have been cut in half by large vessels like ships and tug boats, even in the highly populated lower St Johns River's narrow channels. Some are concerned that the current situation is inhumane, with upwards of 50 scars and disfigurements from vessel strikes on a single manatee. Often, the cuts lead to infections, which can prove fatal. Internal injuries stemming from being trapped between hulls and docks and impacts have also been fatal.

Manatees hear on a higher frequency than would be expected for such large marine mammals. Many large boats emit very low frequencies which confuse the manatee and explain their lack of awareness around boats. National Geographic has done experiments proving that when a boat has a higher frequency the manatees rapidly swim away from danger.

In 2003, a population model was released by the U.S. Geological Survey that predicted an extremely grave situation confronting the manatee in both the Southwest and Atlantic regions where the vast majority of manatees are found. It states,
"In the absence of any new management action, that is, if boat mortality rates continue to increase at the rates observed since 1992, the situation in the Atlantic and Southwest regions is dire, with no chance of meeting recovery criteria within 100 years."

"Hurricanes, cold stress, red tide poisoning and a variety of other maladies threaten manatees, but by far their greatest danger is from watercraft strikes, which account for about a quarter of Florida manatee deaths," said study curator John Jett.


According to marine mammal veterinarian
Veterinarian
A veterinary physician, colloquially called a vet, shortened from veterinarian or veterinary surgeon , is a professional who treats disease, disorder and injury in animals....

s:
"The severity of mutilations for some of these individuals can be astounding - including long term survivors with completely severed tails, major tail mutilations, and multiple disfiguring dorsal lacerations. These injuries not only cause gruesome wounds, but may also impact population processes by reducing calf production (and survival) in wounded females - observations also speak to the likely pain and suffering endured". In an example, they cited one case study of a small calf "with a severe dorsal mutilation trailing a decomposing piece of dermis and muscle as it continued to accompany and nurse from its mother...by age 2 its dorsum was grossly deformed and included a large protruding rib fragment visible."


These veterinarians go on to state:
"the overwhelming documentation of gruesome wounding of manatees leaves no room for denial. Minimization of this injury is explicit in the Recovery Plan, several state statutes, and federal laws, and implicit in our society's ethical and moral standards."


In 2009, of the 429 Florida manatees recorded dead, 97 were killed by commercial and recreational vessels, which broke the earlier record number of 95 set in 2002.

Red tide

Another cause of manatee deaths is the red tide
Red tide
Red tide is a common name for a phenomenon also known as an algal bloom , an event in which estuarine, marine, or fresh water algae accumulate rapidly in the water column and results in discoloration of the surface water. It is usually found in coastal areas...

, a term used for the proliferation, or "blooms", of the microscopic marine algae of the species Karenia brevis
Karenia brevis
Karenia brevis is a marine dinoflagellate common in Gulf of Mexico waters, and is the organism responsible for Florida red tide, as well as red tide in Texas.-Description:K...

, a member of the dinoflagellate
Dinoflagellate
The dinoflagellates are a large group of flagellate protists. Most are marine plankton, but they are common in fresh water habitats as well. Their populations are distributed depending on temperature, salinity, or depth...

s that produces brevetoxin
Brevetoxin
Brevetoxin , or brevetoxins, are a suite of cyclic polyether compounds produced naturally by a species of dinoflagellate known as Karenia brevis...

s that can have toxic effects on the central nervous systems of creatures in the area of the algae bloom.

In 1996, a red tide was responsible for 151 manatee deaths. The epidemic began on March 5 and continued through April 28, wiping out approximately 15% of the known population of manatees along South Florida's western coast.
In 1982, another outbreak resulted in 37 deaths, and in 2005, 44 more deaths were attributed to the blooms.

Additional threats

Manatees occasionally ingest fishing gear (hooks, metal weights, etc.) while feeding. These foreign materials do not appear to harm manatees, except for monofilament line or string, which can clog a manatee's digestive system and slowly kill it.

Manatees can also be crushed in water control structures (navigation locks, floodgate
Floodgate
Floodgates are adjustable gates used to control water flow in flood barriers, reservoir, river, stream, or levee systems. They may be designed to set spillway crest heights in dams, to adjust flow rates in sluices and canals, or they may be designed to stop water flow entirely as part of a levee or...

s, etc.), drown in pipes and culvert
Culvert
A culvert is a device used to channel water. It may be used to allow water to pass underneath a road, railway, or embankment. Culverts can be made of many different materials; steel, polyvinyl chloride and concrete are the most common...

s, and are occasionally killed by entanglement in fishing gear, primarily crab pot float lines.

While humans are allowed to swim with manatees in one area of Florida, there have been numerous charges of people harassing and disturbing the manatees.

The African manatee's only significant threats are due to poaching, habitat loss, and other environmental impacts. They occasionally get stranded as the river dries up at the end of rainy season and are cooked for a meal.

Conservation

All three species of manatee are listed by the World Conservation Union as vulnerable to extinction.

It is illegal under federal and Florida law to injure or harm a manatee. They are classified as "endangered" by both the state and the federal governments.

The MV Freedom Star
MV Freedom Star
-References:*-External links:* * * - On-board video tour of MV Freedom Star conducted by Astronaut Michael J. Massimino...

 and MV Liberty Star
MV Liberty Star
-References:*-External links:*...

, ships used by NASA
NASA
The National Aeronautics and Space Administration is the agency of the United States government that is responsible for the nation's civilian space program and for aeronautics and aerospace research...

 to tow space shuttle
Space Shuttle
The Space Shuttle was a manned orbital rocket and spacecraft system operated by NASA on 135 missions from 1981 to 2011. The system combined rocket launch, orbital spacecraft, and re-entry spaceplane with modular add-ons...

 solid rocket booster
Solid rocket booster
Solid rocket boosters or Solid Rocket Motors, SRM, are used to provide thrust in spacecraft launches from the launchpad up to burnout of the SRBs. Many launch vehicles include SRBs, including the Ariane 5, Atlas V , and the NASA Space Shuttle...

s back to Kennedy Space Center
Kennedy Space Center
The John F. Kennedy Space Center is the NASA installation that has been the launch site for every United States human space flight since 1968. Although such flights are currently on hiatus, KSC continues to manage and operate unmanned rocket launch facilities for America's civilian space program...

, are propelled only by water jets to protect the endangered manatee population that inhabits regions of the Banana River
Banana River
The Banana River is a lagoon that lies between Cape Canaveral and Merritt Island in Brevard County, Florida in the United States. It is part of the Indian River Lagoon system, and connects at its south end to the Indian River; it is the only part of the lagoon system not in the Intracoastal...

 where the ships are based.

Brazil outlawed hunting in 1973 in an effort to preserve the species. Deaths by boat strikes are still common.

Hunting

Manatees were traditionally hunted by indigenous Caribbean people. When Christopher Columbus
Christopher Columbus
Christopher Columbus was an explorer, colonizer, and navigator, born in the Republic of Genoa, in northwestern Italy. Under the auspices of the Catholic Monarchs of Spain, he completed four voyages across the Atlantic Ocean that led to general European awareness of the American continents in the...

 arrived in the region, hunting was already an established trade, although this is less common today.

The primary hunting method was for the hunter to approach in a dugout canoe, offering bait to attract it close enough to temporarily stun it with a blow near the head from an oar-like pole. Many times the creature would flip over, leaving it vulnerable to further attacks.

From manatee hides, Native Americans
Native Americans in the United States
Native Americans in the United States are the indigenous peoples in North America within the boundaries of the present-day continental United States, parts of Alaska, and the island state of Hawaii. They are composed of numerous, distinct tribes, states, and ethnic groups, many of which survive as...

 made war shields
Shield
A shield is a type of personal armor, meant to intercept attacks, either by stopping projectiles such as arrows or redirecting a hit from a sword, mace or battle axe to the side of the shield-bearer....

, canoe
Canoe
A canoe or Canadian canoe is a small narrow boat, typically human-powered, though it may also be powered by sails or small electric or gas motors. Canoes are usually pointed at both bow and stern and are normally open on top, but can be decked over A canoe (North American English) or Canadian...

s, and shoe
Shoe
A shoe is an item of footwear intended to protect and comfort the human foot while doing various activities. Shoes are also used as an item of decoration. The design of shoes has varied enormously through time and from culture to culture, with appearance originally being tied to function...

s, though manatees were predominantly hunted for their abundant meat.

Later, manatees were hunted for their bones, which were used to make "special potions". Until the 1800s, museums paid as much as $100 for bones or hides. Though hunting was banned in 1893, poaching continues today.

Captivity

The oldest manatee in captivity is Snooty
Snooty
Snooty is a Florida Manatee , that resides at the South Florida Museum's Parker Manatee Aquarium in Bradenton, Florida. Born at the Miami Aquarium and Tackle Company on , Snooty was one of the first recorded captive manatee births. Snooty is the oldest manatee in captivity, and likely the oldest...

, at the South Florida Museum
South Florida Museum
The South Florida Museum, located in Bradenton, Florida, is a museum specializing in the natural and cultural history of Florida's gulf coast. It houses exhibits highlighting Florida history from the prehistoric to the present period....

. He was born at the Miami Seaquarium
Miami Seaquarium
The Miami Seaquarium is a oceanarium located on the island of Virginia Key in Biscayne Bay, Miami-Dade County, Florida, United States and is located near downtown Miami. It is the longest operating oceanarium in the United States. In addition to the marine mammals, the Miami Seaquarium also...

 on July 21, 1948 and came to the South Florida Museum
South Florida Museum
The South Florida Museum, located in Bradenton, Florida, is a museum specializing in the natural and cultural history of Florida's gulf coast. It houses exhibits highlighting Florida history from the prehistoric to the present period....

 in Bradenton, Florida
Bradenton, Florida
Bradenton is a city in Manatee County, Florida, United States. The U.S. Census Bureau estimated the city's 2007 population to be 53,471. Bradenton is the largest Principal City of the Bradenton-Sarasota-Venice, Florida Metropolitan Statistical Area, which had a 2007 estimated population of 682,833...

 in 1949.

Manatees can also be viewed in a number of European zoos, such as the Tierpark in Berlin
Berlin
Berlin is the capital city of Germany and is one of the 16 states of Germany. With a population of 3.45 million people, Berlin is Germany's largest city. It is the second most populous city proper and the seventh most populous urban area in the European Union...

, the Nuremberg Zoo, in Beaval Park Zoo in France and in the Aquarium of Genoa
Aquarium of Genoa
The Aquarium of Genoa is the largest aquarium in Italy and the second largest in Europe. Located in the old harbor area of Genoa, Italy, the aquarium is a member organization of the European Association of Zoos and Aquaria , and welcomes more than 1.2 million visitors each year.-History:The...

 in Italy.

They are also included in the plans for a new National Wildlife Conservation Park
National Wildlife Conservation Park
The National Wildlife Conservation Park is a proposed extension to Bristol Zoo.In 2008 Bristol Zoo Gardens announced plans to submit plans to South Gloucestershire Council for the development of a new 55-hectare National Wildlife Conservation Park...

 in Bristol, England, which is due to open in 2012 with the manatees as an addition in 2015.

Culture

The manatee has been linked to folklore on mermaid
Mermaid
A mermaid is a mythological aquatic creature with a female human head, arms, and torso and the tail of a fish. A male version of a mermaid is known as a "merman" and in general both males and females are known as "merfolk"...

s. Native Americans
Native Americans in the United States
Native Americans in the United States are the indigenous peoples in North America within the boundaries of the present-day continental United States, parts of Alaska, and the island state of Hawaii. They are composed of numerous, distinct tribes, states, and ethnic groups, many of which survive as...

 ground the bones to treat asthma
Asthma
Asthma is the common chronic inflammatory disease of the airways characterized by variable and recurring symptoms, reversible airflow obstruction, and bronchospasm. Symptoms include wheezing, coughing, chest tightness, and shortness of breath...

 and earache. In West Africa
West Africa
West Africa or Western Africa is the westernmost region of the African continent. Geopolitically, the UN definition of Western Africa includes the following 16 countries and an area of approximately 5 million square km:-Flags of West Africa:...

n folklore, they were sacred and thought to have been once human. Killing one was taboo
Taboo
A taboo is a strong social prohibition relating to any area of human activity or social custom that is sacred and or forbidden based on moral judgment, religious beliefs and or scientific consensus. Breaking the taboo is usually considered objectionable or abhorrent by society...

and required penance.

External links

The source of this article is wikipedia, the free encyclopedia.  The text of this article is licensed under the GFDL.
 
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