Manatees ( family Trichechidae, genus Trichechus ) are big, in full aquatic, by and large herbivorous marine mammals sometimes known as sea cows. There are three accept living species of Trichechidae, representing three of the four be species in the ordain Sirenia : the Amazonian manatee ( Trichechus inunguis ), the West indian manatee ( Trichechus manatus ), and the west african manatee ( Trichechus senegalensis ). They measure up to 4.0 metres ( 13 foot 1 in ) long, consider arsenic much as 590 kilograms ( 1,300 pound ), [ 2 ] and have paddle-like flippers. Manatees are herbivores and corrode over 60 different fresh water and seawater plants. Manatees inhabit the shallow, boggy coastal areas and rivers of the Caribbean Sea, the Gulf of Mexico, the Amazon river basin, and West Africa.
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The main causes of death for manatees are human-related issues, such as habitat end and human objects. Their slow-moving, curious nature has led to violent collisions with propeller-driven boats and ships. Some manatees have been found with over 50 scars on them from propeller blades. natural causes of death include adverse temperatures, predation by crocodiles on young, [ 3 ] and disease .
etymology
The etymology of the mention is ill-defined, with connections having been made to Latin manus “ pass ” and to pre-columbian Taíno manati “ breast ”. [ 4 ] The terminus sea cow is a reference to the species ‘ slowly, peaceful, herbivorous nature, evocative of that of bovines. [ 5 ]
taxonomy
Manatees are three of the four living species in the order Sirenia. The fourth is the Eastern Hemisphere ‘s dugong. The Sirenia are thought to have evolved from four-legged land mammals more than 60 million years ago, with the closest living relatives being the Proboscidea ( elephants ) and Hyracoidea ( hyraxes ). [ 6 ] The Amazonian ‘s haircloth color is brown grey, and it has thick wrinkled skin, frequently with coarse hair’s-breadth, or “ whiskers ”. Photos are rare ; although very little is known about this species, scientists think it is like to West indian manatee .
description
Skull of a West indian manatee, the Museum of Osteology, Oklahoma City Manatees weigh 400 to 550 kg ( 880 to 1,210 pound ), and average 2.8 to 3.0 megabyte ( 9 foot 2 in to 9 ft 10 in ) in duration, sometimes growing to 4.6 molarity ( 15 foot 1 in ) and 1,775 kilogram ( 3,913 pound ) and females tend to be larger and heavier than males. At give birth, child manatees weigh about 30 kg ( 66 pound ) each. The female manatee has two teats, one under each flipper, [ 7 ] a characteristic that was used to make early links between the manatee and elephants. The lids of manatees ‘ little, widely spaced eyes close in a circular manner. The manatee has a large, elastic, prehensile upper lip, used to gather food and feed and for social interaction and communication. Manatees have shorter snouts than their companion sirenians, the dugongs. manatee adults have no incisor or canine teeth, just a set of cheek teeth, which are not clearly differentiated into molars and premolars. These teeth are repeatedly replaced throughout life, with new teeth growing at the rear as older dentition fall out from farther forward in the mouth, slightly as elephants ‘ teeth do. [ 8 ] [ 9 ] At any prison term, a manatee typically has no more than six teeth in each jaw of its mouth. [ 9 ] The manatee ‘s tail is paddle-shaped, and is the clear visible difference between manatees and dugongs ; a dugong dock is fluked, similar in determine to that of a whale. The manatee is unusual among mammals in having just six cervical vertebra, [ 10 ] a number that may be ascribable to mutations in the homeotic genes. [ 11 ] All other mammals have seven cervical vertebra, [ 12 ] other than the two-toed and three-toed sloths. Like the knight, the manatee has a simpleton abdomen, but a large cecum, in which it can digest hard establish matter. by and large, the intestines are about 45 meters, unusually long for an animal of the manatee ‘s size. [ 13 ] [ better source needed ]
evolution
Fossil remains of manatee ancestors – besides known as sirenians – go steady back to the early Eocene. [ 14 ] [ 15 ] It is thought that they reached the isolated area of the south american continent and became known as Trichechidae. In the Late Miocene, trichechids were likely restricted in south american coastal rivers and they fed on many fresh water plants. Dugongs inhabited the West Atlantic and Caribbean waters and fed on seagrass meadows alternatively. As the ocean grasses began to grow, manatees adapted to the changing environment by growing supernumerary molars. Sea levels lowered and increased erosion and silt overflow was caused by glaciation. This increased the tooth wear of the bottom-feeding manatees. [ 16 ]
demeanor
Trichechus manatus) Endangered Florida manatee ( apart from mothers with their new, or males following a receptive female, manatees are by and large solitary confinement animals. [ 9 ] Manatees spend approximately 50 % of the day sleeping submerged, surfacing for air regularly at intervals of less than 20 minutes. The remainder of the time is by and large spend graze in shallow waters at depths of 1–2 thousand ( 3 foot 3 in–6 foot 7 in ). The Florida subspecies ( T. m. latirostris ) has been known to live up to 60 years .
locomotion
generally, manatees swim at about 5 to 8 km/h ( 3 to 5 miles per hour ). however, they have been known to swim at up to 30 km/h ( 20 miles per hour ) in short bursts. [ 17 ]
intelligence and eruditeness
manatee postures in enslavement Manatees are capable of understanding discrimination tasks and show signs of complex associative learn. They besides have good long-run memory. [ 18 ] They demonstrate discrimination and task-learning abilities exchangeable to dolphins and pinnipeds in acoustic and ocular studies. [ 19 ]
replica
Manatees typically breed once every two years ; by and large entirely a individual calf is born. pregnancy lasts about 12 months and to wean the calf takes a further 12 to 18 months, [ 9 ] although females may have more than one estrous hertz per class. [ 20 ]
communication
Manatees emit a across-the-board stove of sounds used in communication, specially between cows and their calves. [ 21 ] Their ears are big internally but the external openings are small, and they are located four inches behind each eye. [ 22 ] Adults communicate to maintain contact and during intimate and play behaviors. taste and smell, in accession to view, sound, and allude, may besides be forms of communication. [ 23 ]
diet
Manatees are herbivores and feed over 60 unlike fresh water ( for example, floating hyacinth, pickerel weed, alligator weed, water lettuce, hydrilla, body of water celery, musk grass, mangrove leaves ) and seawater plants ( for example, sea grasses, shoal grass, manatee denounce, turtleneck grass, widgeon eatage, sea clover, and marine alga ). [ 24 ] [ 25 ] Using their divided upper lip, an adult manatee will normally eat up to 10 % –15 % of their body weight ( about 50 kg ) per day. Consuming such an amount requires the manatee to graze for up to seven hours a day. [ 26 ] To be able to cope with the high levels of cellulose in their plant based diet, manatees utilize hindgut zymosis to help with the digestion process. [ 27 ] Manatees have been known to eat little numbers of pisces from nets. [ 28 ]
Feeding behavior
manatee plate Manatees use their flippers to “ walk ” along the bottom whilst they dig for plants and roots in the substrate. When plants are detected, the flippers are used to scoop the vegetation toward the manatee ‘s lips. The manatee has prehensile lips ; the amphetamine brim diggings is split into bequeath and mighty sides which can move independently. The lips use seven muscles to manipulate and tear at plants. Manatees use their lips and front flippers to move the plants into the talk. The manatee does not have front teeth, however, behind the lips, on the roof of the mouthpiece, there are dense, ridged pads. These corneous ridges, and the manatee ‘s lower jaw, tear through ingested plant material. [ 26 ]
dentition
Manatees have four rows of tooth. There are 6 to 8 high-crowned, open-rooted molars located along each side of the upper and lower call on the carpet giving a entire of 24 to 32 apartment, textured tooth. Eating game vegetation abrades the teeth, particularly the enamel pennant ; however, research indicates that the enamel structure in manatee molars is weak. To compensate for this, manatee teeth are continually replaced. When anterior molars wear down, they are shed. Posterior molars erupt at the back of the row and slowly move forward to replace these like enamel crowns on a conveyer belt, similarly to elephants. This process continues throughout the manatee ‘s life. The rate at which the dentition migrate forward depends on how cursorily the anterior teeth scour. Some studies indicate that the rate is about 1 cm/month although other studies indicate 0.1 cm/month. [ 26 ]
ecology
Range and habitat
Trichechus; T. manatus in green; T. inunguis in red; T. senegalensis in orange Approximate distribution ofin greens ; in crimson ; in orange
Three manatees
Mother manatee and calf Manatees inhabit the shallow, boggy coastal areas and rivers of the Caribbean Sea and the Gulf of Mexico ( T. manatus, West Indian manatee ), the Amazon basin ( T. inunguis, Amazonian manatee ), and West Africa ( T. senegalensis, West African manatee ). [ 29 ] West indian manatees prefer warm temperatures and are known to congregate in shallow waters. They frequently migrate through brackish body of water estuaries to freshwater springs. They can not survive below 15 °C ( 60 °F ). Their natural reservoir for heat during winter is warm, spring-fed rivers .
West amerind
The slide of the state of Georgia is normally the northernmost range of the West indian manatees because their moo metabolic rate does not protect them in cold water. Prolonged vulnerability to body of water below 20 °C ( 68 °F ) can cause “ cold stress syndrome ” and death. [ 30 ] Florida manatees can move freely between fresh water and salt water. Manatees have been seen as far north as Cape Cod, and in 1995 [ 31 ] and again in 2006, one was seen in New York City [ 32 ] and Rhode Island ‘s Narragansett Bay. A manatee was spotted in the Wolf River seaport near the Mississippi River in downtown Memphis in 2006, and was former found dead 16 kilometer ( 10 secret intelligence service ) downriver in McKellar Lake. [ 33 ] Another manatee was found dead on a New Jersey beach in February 2020, considered particularly unusual given the time of year. [ 34 ] At the time of the manatee ‘s discovery, the urine temperature in the sphere was below 6.5 °C ( 43.7 °F ). [ 35 ] The West indian manatee migrates into Florida rivers—such as the Crystal, the Homosassa, and the Chassahowitzka rivers, whose headsprings are 22 °C ( 72 °F ) all year. Between November and March each year, about 600 West indian manatees gather in the rivers in Citrus County, Florida such as the Crystal River National Wildlife Refuge. [ 36 ] In winter, manatees often gather near the warm-water outflows of power plants along the Florida slide, rather of migrating confederacy as they once did. Some conservationists are concerned that these manatees have become excessively reliant on these artificially warmed areas. [ 37 ] The U.S. Fish and Wildlife Service is trying to find a raw way to heat the water for manatees that depended on plants that have closed. Studies suggest that Florida manatees need access to fresh water for proper regulation of urine and salts in their bodies. Accurate population estimates of the Florida manatee ( T. manatus ) are unmanageable. They have been called scientifically weak [ 38 ] because they vary widely from year to year, some areas showing increases, others decreases, and little solid tell of increases except in two areas. manatee counts are highly variable star without an accurate way to estimate numbers : In Florida in 1996, a winter review found 2,639 manatees ; in 1997, a January survey found 2,229, and a February sketch found 1,706. [ 19 ] A statewide synoptic surveil in January 2010 found 5,067 manatees living in Florida, the highest number recorded to that clock time. [ 39 ] As of January 2016, the USFWS estimates the range-wide manatee population to be at least 13,000 ; as of January 2018, at least 6,100 are estimated to be in Florida. [ 40 ] [ 41 ] Population viability studies conducted in 1997 found that decreasing pornographic survival and eventual extinction were a probable future consequence for Florida manatees unless they got more auspices. [ 42 ] The U.S. Fish and Wildlife Service proposed downgrading the manatee ‘s condition from endangered to threatened in January 2016 after more than 40 years of the manatee ‘s being classified as on the endangered. [ 43 ]
Amazonian
The fresh water Amazonian manatee ( T. inunguis ) inhabits the Central Amazon Basin in Brazil, easterly Perú, southeastern Colombia, but not Ecuador. It is the alone entirely fresh water manatee, and is besides the smallest. Since they are unable to reduce peripheral heating system loss, it is found chiefly in tropical waters .
west african
They are found in coastal marine and estuarine habitats, and in fresh water river systems along the west seashore of Africa from the Senegal River south to the Cuanza River in Angola. They live as far upriver on the Niger River as Koulikoro in Mali, 2,000 kilometer from the slide. [ 44 ]
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predation
In relative to the terror posed by humans, predation does not present a significant threat to manatees. [ 14 ] When threatened, the manatee ‘s response is to dive american samoa deeply as it can, suggesting that threats have most frequently come from state dwellers such as humans rather than from other water-dwelling creatures such as caimans or sharks. [ 14 ]
relation back to humans
youthful manatees can be curious ; this individual is inspecting a kayak 
Antillean manatee
Threats
The main causes of death for manatees are human-related issues, such as habitat destruction and human objects. natural causes of end include adverse temperatures, depredation by crocodiles on young, [ 45 ] and disease. [ citation needed ]
Ship strikes
Their slow-moving, curious nature, coupled with dense coastal exploitation, has led to many violent collisions with propeller-driven boats and ships, leading frequently to maim, defacement, and even death. As a resultant role, a bombastic symmetry of manatees exhibit spiral cutting propeller scars on their backs, normally caused by larger vessels that do not have skegs in front of the propellers like the smaller outboard motor and inboard-outboard amateur boats have. They are now even identified by humans based on their scar patterns. many manatees have been cut in two by big vessels like ships and tug boats, flush in the highly populate lower St. Johns River ‘s narrow-minded channels. Some are concerned that the current position is inhumane, with upwards of 50 scars and disfigurements from vessel strikes on a single manatee. [ 46 ] Often, the lacerations lead to infections, which can prove fateful. Internal injuries stemming from being trapped between hulls and docks and impacts have besides been fatal. late testing [ citation needed ] shows that manatees may be able to hear amphetamine boats and other vessel set about, due to the frequency the boat makes. however, a manatee may not be able to hear the approaching boats when they are performing daily activities or distractions. The manatee has a tested frequency roll of 8 to 32 kilohertz. [ citation needed ] Manatees hear on a higher frequency than would be expected for such big marine mammals. many large boats emit very low frequencies, which confuse the manatee and explain their lack of awareness around boats. The Lloyd ‘s mirror effect results in abject frequency propeller sounds not being discernible near the surface, where most accidents occur. Research indicates that when a boat has a higher frequency the manatees quickly swim away from danger. [ 47 ] In 2003, a population exemplary was released by the United States Geological Survey that predicted an extremely scratch situation confronting the manatee in both the Southwest and Atlantic regions where the huge majority of manatees are found. It states ,
In the absence of any new management natural process, that is, if boat mortality rates continue to increase at the rates observed since 1992, the situation in the Atlantic and Southwest regions is desperate, with no luck of meeting convalescence criteria within 100 years. [ 48 ] “ Hurricanes, cold stress, red tide poison and a diverseness of early maladies threaten manatees, but by far their greatest danger is from watercraft strikes, which account for about a quarter of Florida manatee deaths, ” said sketch curator John Jett. [ 49 ]
According to marine mammal veterinarians :
Manatee bearing scars on its back from a gravy boat propeller .
The severity of mutilations for some of these individuals can be astounding – including long term survivors with completely severed tails, major stern mutilations, and multiple deface abaxial lacerations. These injuries not only cause ghastly wounds, but may besides impact population processes by reducing calf production ( and survival ) in hurt females – observations besides speak to the probably annoyance and suffering endured. [ 19 ] In an example, they cited one font study of a little calf “ with a severe dorsal mutilation trailing a decomposing while of dermis and muscleman as it continued to accompany and nurse from its mother … by age 2 its back was grossly deformed and included a big start rib shard visible. ” [ 19 ]
These veterinarians go on to express :
[ T ] he overwhelming documentation of ghastly wound of manatees leaves no room for denial. minimization of this wound is explicit in the Recovery Plan, respective state statutes, and federal laws, and implicit in our society ‘s ethical and moral standards. [ 19 ]
One quarter of annual manatee deaths in Florida are caused by gravy boat collisions with manatees. [ 50 ] In 2009, of the 429 Florida manatees recorded dead, 97 were killed by commercial and amateur vessels, which broke the earlier record number of 95 set in 2002. [ 51 ] [ 52 ]
loss tide
Another lawsuit of manatee deaths are red tides, a term used for the proliferation, or “ blooms ”, of the microscopic marine alga Karenia brevis. This dinoflagellate produces brevetoxins that can have toxic effects on the central aflutter system of animals. [ 53 ] In 1996, a red tide was responsible for 151 manatee deaths in Florida. [ 54 ] The bloom was confront from early March to the end of April and killed approximately 15 % of the know population of manatees along South Florida ‘s western coast. [ 55 ] other blooms in 1982 and 2005 resulted in 37 and 44 deaths, respectively. [ 56 ]
extra threats
Manatees can besides be crushed and isolated in water control structures ( navigation locks, floodgates, etc. ) and are occasionally killed by web in fishing gear, such as crab toilet float lines, box traps, and shark nets. [ 44 ] While humans are allowed to swim with manatees in one area of Florida, [ 57 ] there have been numerous charges of people harassing and disturbing the manatees. [ 58 ] According to the United States Fish and Wildlife Service, approximately 99 manatee deaths each year are related to human activities. [ 59 ] In January 2016, there were 43 manatee deaths in Florida alone. [ 60 ]
conservation
All three species of manatee are listed by the World Conservation Union as vulnerable to extinction. however, The U.S. Fish and Wildlife Service ( FWS ) does not consider the West indian manatee to be “ endangered ” anymore, having downgraded its condition to “ threatened ” as of March 2017. They cite improvements to habitat conditions, population growth and reductions of threats as reasoning for the change. The reclassification was met with controversy, with Florida congressman Vern Buchanan and groups such as the Save the Manatee Club and the Center for Biological Diversity expressing concerns that the change would have a damaging effect on conservation efforts. [ 61 ] The newly classification will not affect current federal protections. [ 40 ] West indian manatees were primitively classified as endangered with the 1967 class of endanger species. [ 62 ] Manatee population in the United States reached a depleted in the 1970s, during which lone a few hundred individuals lived in the state. [ 63 ] As of February 2016, 6,250 manatees were reported swim in Florida ‘s springs. [ 64 ] It is illegal under federal and Florida law to injure or harm a manatee. There are many conservation programs that have been created to help manatees. Save the Manatee Club is a non-profit group and membership administration that works to protect manatees and their aquatic ecosystems. Founded by Bob Graham, former Florida governor, and singer/songwriter Jimmy Buffett, this is today ‘s go manatee conservation club. [ 65 ] The MV Freedom Star and MV Liberty Star, ships used by NASA to tow Space Shuttle Solid Rocket Boosters binding to Kennedy Space Center, were propelled only by water jets to protect the endangered manatee population that inhabits regions of the Banana River where the ships are based. Brazil outlawed hunting in 1973 in an feat to preserve the species. Deaths by boat strikes are placid park. [ citation needed ] Although countries are protecting Amazonian manatees in the locations where they are endangered, as of 1994 there were no enforce laws, and the manatees were silent being captured throughout their range. [ 66 ]
captivity
A manatee at SeaWorld, Florida The oldest manatee in captivity was Snooty, [ 67 ] at the South Florida Museum ‘s Parker Manatee Aquarium in Bradenton, Florida. Born at the Miami Aquarium and Tackle Company on July 21, 1948, Snooty was one of the beginning recorded captive manatee births. Raised wholly in enslavement, Snooty was never to be released into the wilderness. As such he was the only manatee at the aquarium, and one of only a few captive manatees in the United States that was allowed to interact with human handlers. That made him uniquely desirable for manatee research and education. [ 68 ] Snooty died abruptly two days after his 69th birthday, July 23, 2017, when he was found in an subaqueous area merely used to access plumb for the show life patronize arrangement. The South Florida Museum ‘s initial press release stated, “ early indications are that an access gore door that is normally bolted close had somehow been knocked loose and that Snooty was able to swim in. ” [ 69 ] There are a number of manatee rehabilitation centers in the United States. These include three government-run critical worry facilities in Florida at Lowry Park Zoo, Miami Seaquarium, and SeaWorld Orlando. After initial treatment at these facilities, the manatees are transferred to rehabilitation facilities before release. These include the Cincinnati Zoo and Botanical Garden, Columbus Zoo and Aquarium, Epcot ‘s The Seas, South Florida Museum, and Homosassa Springs Wildlife State Park. [ 70 ] The Columbus Zoo was a initiation member of the Manatee Rehabilitation Partnership in 2001. Since 1999, the menagerie ‘s Manatee Bay adeptness has helped rehabilitate 20 manatees. [ 71 ] The Cincinnati Zoo has rehabilitated and released more than a twelve manatees since 1999. [ 72 ] Manatees can besides be viewed in a total of european menagerie, such as the Tierpark Berlin and the Nuremberg Zoo in Germany, in ZooParc de Beauval in France, the Aquarium of Genoa in Italy and the Royal Burgers ‘ Zoo in Arnhem, the Netherlands, where manatees have parented offspring. [ 73 ] The River Safari at Singapore features seven of them. [ 74 ]
Guyana
Since the nineteenth hundred, Georgetown, Guyana has kept West amerind manatees in its botanical garden, and later, its national parking lot. [ 75 ] In the 1910s and again in the 1950s, sugar estates in Guyana used manatees to keep their irrigation canals weed-free. [ 76 ] Between the 1950s and 1970s, the Georgetown water discussion plant used manatees in their storage canals for the same purpose. [ 77 ]
culture
The manatee has been linked to folklore on mermaids. [ citation needed ] In west african folklore, they were considered sacred and thought to have been once human. Killing one was taboo and needed penance. [ 78 ] In the novel Moby-Dick, Herman Melville distinguishes manatees ( “ Lamatins ”, cystic fibrosis. lamantins ) from humble whales ; stating, “ I am aware that down to the give time, the fish styled Lamatins and Dugongs ( Pig-fish and Sow-fish of the Coffins of Nantucket ) are included by many naturalists among the whales. But as these pig-fish are a noisy, contemptible set, by and large lurking in the mouths of rivers, and feeding on wet hay, and specially as they do not spout, I deny their credentials as whales ; and have presented them with their passports to quit the Kingdom of Cetology. ” [ 79 ]
See besides
References
promote understand
- Hall, Alice J. (September 1984). “Man and Manatee: Can We Live Together?”. National Geographic. Vol. 166 no. 3. pp. 400–418. ISSN 0027-9358. OCLC 643483454.