Manatee – Part 4

Captivity

Underwater photo of manatee

A manatee at SeaWorld, Florida

The oldest manatee in captivity was Snooty, 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 first recorded captive manatee births. Raised entirely in captivity, Snooty was never to be released into the wild. 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 suitable for manatee research and education.

Snooty died suddenly two days after his 69th birthday, July 23, 2017, when he was found in an underwater area only used to access plumbing for the exhibit life support system. The South Florida Museum’s initial press release stated, “Early indications are that an access panel door that is normally bolted shut had somehow been knocked loose and that Snooty was able to swim in.”[

There are a number of manatee rehabilitation centers in the United States. These include three government-run critical care 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.[

The Columbus Zoo was a founding member of the Manatee Rehabilitation Partnership in 2001. Since 1999, the zoo’s Manatee Bay facility has helped rehabilitate 20 manatees. The Cincinnati Zoo has rehabilitated and released more than a dozen manatees since 1999.[

Manatees can also be viewed in a number of European zoos, such as the Tierpark Berlin, the Nuremberg Zoo, in ZooParc de Beauval in France and in the Aquarium of Genoa in Italy. The River Safari at Singapore features seven of them.[ They are also included in the plans of the Wild Place Project in Bristol, England, whose first exhibit is opened in summer 2013 with the manatees as an addition as early as 2015.[

Culture

The manatee has been linked to folklore on mermaids. Native Americans ground the bones to treat asthma and earache. In West African folklore, they were considered sacred and thought to have been once human. Killing one was taboo and required penance.[

In the novel Moby-Dick, Herman Melville distinguishes manatees (“Lamatins”) from small whales; stating, “I am aware that down to the present 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, mostly lurking in the mouths of rivers, and feeding on wet hay, and especially as they do not spout, I deny their credentials as whales; and have presented them with their passports to quit the Kingdom of Cetology.”[

Manatees were featured in the “Cartoon Wars Part II” episode of South Park, as the creative force behind the television show Family Guy. The manatees were shown to be living in a tank at FOX Studios which was filled with “idea balls.” The manatees randomly selected the idea balls to make the jokes for the show. They are also revealed as being “the only animal unmoved by terrorist threats.”[ The manatee is also pivotal in Lair of the Leviathan, the third episode of the game Tales of Monkey Island, by Telltale Games and Lucasarts.

(Information from Wikipedia.com)

Manatee – Part 3

Ecology

Range and habitat

Manatees inhabit the shallow, marshy 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).[

West Indian manatees prefer warmer temperatures and are known to congregate in shallow waters. They frequently migrate through brackish water estuaries to freshwater springs. They cannot survive below 15 °C (60 °F). Their natural source for warmth during winter is warm, spring-fed rivers.

Underwater photo of three manatees swimming along bottom

A group of three manatees

West Indian

The coast of the state 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 below 20 °C (68 °F) can cause “cold stress syndrome” and death.[

Florida manatees can move freely between fresh water and salt water.

Manatees have been seen as far north as Cape Cod, and in 1995 and again in 2006, one was seen in New York City and Rhode Island’s Narragansett Bay. A manatee was spotted in the Wolf River harbor near the Mississippi River in downtown Memphis in 2006, and was later found dead 10 miles downriver in McKellar Lake.

The West Indian manatee migrates into Florida rivers—such as the Crystal, the Homosassa, and the Chassahowitzka rivers, whose head springs are 22 °C (72 °F) all year. In November to March, about 400 West Indian manatees (according to the National Wildlife Refuge) gather in the rivers in Citrus County, Florida.

In winter, manatees often gather near the warm-water outflows of power plants along the Florida coast, instead of migrating south as they once did. Some conservationists are concerned that these manatees 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 depended on plants that have closed. The main water treatment plant in Guyana has four manatees that keep storage canals clear of weeds; there are also some in the ponds of the national park in Georgetown, Guyana.

Studies suggest that Florida manatees need access to fresh water for proper regulation of water and salts in their bodies.

Accurate population estimates of the Florida manatee (T. manatus) are difficult. They have been called scientifically weak because they vary widely from year to year, some areas showing increases, others decreases, and 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, the highest number recorded to that time.[

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.[

Population viability studies conducted in 1997 found that decreasing adult survival and eventual extinction were a probable future outcome for Florida manatees unless they got more protection. The U.S. Fish and Wildlife Service proposed downgrading the manatee’s status from endangered to threatened in January 2016 after more than 40 years of the manatee’s being classified as on the endangered.[

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

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 south to the Cuanza River in Angola. They live as far upriver on the Niger River as Koulikoro in Mali, 2,000 km from the coast.

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 and MV Liberty Star, ships used by NASA to tow space shuttle solid rocket boosters back to Kennedy Space Center, are 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 effort to preserve the species. Deaths by boat strikes are still common.

In January 2016, the U.S. Fish and Wildlife Service proposed that the West Indian manatee be reclassified from an “endangered” status to “threatened” as improvements to habitat conditions, population growth and reductions of threats have all increased. The proposal will not affect current federal protections.[

As of February 2016, 6,250 manatees were reported swimming in Florida’s springs.[

Hunting

Underwater profile photo of light-colored animal with small flippers

T

Manatees were traditionally hunted by indigenous Caribbean people. When Christopher Columbus 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 made war shields, canoes, and shoes, 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.

More about Mantees in Part 4 of this series!

(Information obtained from Wikipedia.com)

Manatee – Part 2

Behavior

Endangered Florida manatee (Trichechus manatus)

Apart from mothers with their young, or males following a receptive female, manatees are generally solitary animals. 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 mostly spent grazing in shallow waters at depths of 1–2 metres (3.3–6.6 ft). The Florida subspecies (T. m. latirostris) has been known to live up to 60 years.

Locomotion

Generally, manatees swim at about 5 to 8 kilometres per hour (3 to 5 mph). However, they have been known to swim at up to 30 kilometres per hour (20 mph) in short bursts.[

Intelligence and learning

Manatees are capable of understanding discrimination tasks and show signs of complex associative learning. They also have good long-term memory. They demonstrate discrimination and task-learning abilities similar to dolphins and pinnipeds in acoustic and visual studies.

Reproduction

Manatees typically breed once every two years; generally only a single calf is born. Gestation lasts about 12 months and to wean the calf takes a further 12 to 18 months.[

Communication

Manatees emit a wide range of sounds used in communication, especially between cows and their calves. Their ears are large internally but the external openings are small, and they are located four inches behind each eye. 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 freshwater ( e.g. floating hyacinth, pickerel weed, alligator weed, water lettuce, hydrilla, water celery, musk grass, mangrove leaves) and saltwater plants (e.g. sea grasses, shoal grass, manatee grass, turtle grass, widgeon grass, sea clover, and marine algae). Using their divided upper lip, an adult manatee will commonly 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. To be able to cope with the high levels of cellulose in their plant based diet, manatees utilize hindgut fermentation to help with the digestion process. Manatees have been known to eat small numbers of fish from nets.[

Feeding behavior

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 upper lip pad is split into left and right 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 mouth. The manatee does not have front teeth, however, behind the lips, on the roof of the mouth, there are dense, ridged pads. These horny ridges, and the manatee’s lower jaw, tear through ingested plant material.

Dentition

Manatees have four rows of teeth. There are 6 to 8 high-crowned, open-rooted molars located along each side of the upper and lower jaw giving a total of 24 to 32 flat, rough-textured teeth. Eating gritty vegetation abrades the teeth, particularly the enamel crown; 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 conveyor belt, similarly to elephants. This process continues throughout the manatee’s lifetime. The rate at which the teeth migrate forward depends on how quickly the anterior teeth abrade. Some studies indicate that the rate is about 1 cm/month although other studies indicate 0.1 cm/month.

More about these gentle sea creatures in Part 3 of this series!

(Information
from Wikipedia, the free encyclopedia)

Manatee – Part 1

Manatees are large, fully aquatic, mostly herbivorous marine mammals sometimes known as sea cows. There are three accepted living species of Trichechidae, representing three of the four living species in the order 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 (13.1 ft) long, weigh as much as 590 kilograms (1,300 lb), and have paddle-like flippers.  Manatees are occasionally called sea cows, as they are slow plant-eaters, peaceful and similar to cows on land. They often graze on water plants in tropical seas.

FL fig04.jpg

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).[

The Amazonian’s hair color is brownish gray, and it has thick wrinkled skin, often with coarse hair, or “whiskers”. Photos are rare; although very little is known about this species, scientists think it is similar to West Indian manatee.

Description

Manatees weigh 400 to 550 kilograms (880 to 1,210 lb), and average 2.8 to 3.0 metres (9.2 to 9.8 ft) in length, sometimes growing to 4.6 metres (15 ft) and 1,775 kilograms (3,913 lb) (the females tend to be larger and heavier). At birth, baby manatees weigh about 30 kilograms (66 lb) each. The manatee has a large, flexible, prehensile upper lip, used to gather food and eat and for social interaction and communication. Manatees have shorter snouts than their fellow sirenians, the dugongs. The lids of manatees’ small, widely spaced eyes close in a circular manner. The 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 teeth fall out from farther forward in the mouth, somewhat as elephants’ teeth do. At any 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 that of a whale. The female manatee has two teats, one under each flipper, a characteristic that was used to make early links between the manatee and elephants.

The manatee is unusual among mammals in having just six cervical vertebrae, a number that may be due to mutations in the homeotic genes. All other mammals have seven cervical vertebrae, other than the two-toed and three-toed sloths.

Like the horse, the manatee has a simple stomach, but a large cecum, in which it can digest tough plant matter. Generally, the intestines are about 45 meters, unusually long for an animal of the manatee’s size.

skeleton of a manatee and calf, on display at The Museum of Osteology, Oklahoma City, Oklahoma

More about these gentle giants in Part 2 of Manatees.

(Information from Wikipedia, the free encyclopedia)