THE MANATEE
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Order: SireniaFamily: TrichechidaeGenus: Trichechus
The manatee is part of the order Sirenia and represents three out of the four species within this order. It is believed that manatees evolved from four-footed land animals about 45 million years ago, with their closest living relatives being elephants, aardvarks, and hyraxes. The manatee is commonly referred to as the sea cow, due to the fact that it spends most of his time grazing on seagrasses like cows, who spend much of their time grazing on grass. In ancient times, sailors often mistook manatees for mermaids or sirens due to their tails and graceful swimming.
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Manatee or Mermaid. Can you tell the difference?






















Physical Description
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12 ft. manatee compared to a 6 ft. human
Size Range: 8 - 13 ft. (average = 10 ft.)
Weight Range: 800 - 1,200 lbs (Females tend to be larger and heavier) Life Span: 40-50 years; but can live up to 60 years The oldest living manatee is Snooty who was born in captivity in 1948, making him 63 years old. Swimming Speeds: 2 - 6 mph. Can swim up to speeds of 20 mph for short bursts


The manatee is a hairless mammal, with colors ranging from gray to brown. The color of the skin is dependent on ectobionts, similar to algae, that grow on their skin. The skin is rough and wrinkled. Manatees have extra dense bones which enable them to stay suspended at or just below the waters surface. The bones are so dense because no marrow is found within them, which also makes the bones more brittle and vulnerable to breaking. Manatees have two flippers that are an important part of their physicality. Along with the tail, the flippers are used for steering through the water. The flippers are also used like a "human hand"- bringing food to the manatee's mouth, holding objects, and for crawling on the bottom of shallow waters. The manatee cannot turn his head because he only has six cervical vertebrae, instead of seven like most mammals. In order to look around, they must turn their whole body. The upper lip is large and flexible, like a small trunk that is used for gathering and eating food. For eating food, manatees lack incisors and canine teeth, but have "marching molars". These molars are an evolutionary adaptation due to their diet and are continually being replaced throughout the lifespan of the manatee. Manatees do not have external ears, but they still have an extremely sharp auditory system- being able to hear sounds of varying frequencies, such as the"hum" of boats.
View of video of a manatee using his flippers like hands (0:20 - 0:40):


HabitatManatees are migratory animals that can live in both saltwater and freshwater habitats. They especially like shallow inlets, river estuaries, and bays. The manatee rarely goes out into the open ocean. They prefer warm water with temperatures of 60°F or higher. Large populations of manatees are particularly found in places where seagrass beds or freshwater vegetation flourish.
The three species of manatees are distinguished by their geographic location:
  • WestIndian Manatee: found in mar
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    Habitat Range- Light yellow areas indicate where manatees can be found
    shy, coastal areas and rivers of the Caribbean Sea and Gulf of Mexico
  • Amazonian Manatee: found along the Amazon Basin and in the Amazon River
  • West African Manatee: found on the West Coast and in rivers of Africa





Diet
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The manatees' habitat is directly related to what they like to eat. Manatees are herbivores and eat over sixty different plant species. These include mangrove leaves, turtle grass, and different types of algae. The "marching molars" are used to chew on the vegetation. Manatees eat up to 10-15% of their body weight daily. For a 1,200 lb. manatee, that's up to a 180 lbs. of food a day!






DAILY LIFEFor the most part, manatees are solitary creatures, with the primary social unit consisting of the female taking care of her most recent calf. On occasion they can be seen in herds of twenty or more, but this is rare. These herds have no real leaders or hierarchal structures.
The primary activity for manatees is sleeping, but since manatees are mammals, they still need air to breath. When resting, they can stay submerged for 20 minutes. On average, they come up for air every 3-5 minutes. It is thought that when asleep, manatees may not fully awaken when they come up to the surface to breathe.
Since, manatees consume about 10-15% of their body weight daily, eating is another major activity. In the summer months, manatees may form loosely associated herds that gather for feeding, but these usually disperse quickly, within a few days or a couple of weeks.

Manatees are really gentle and incapable of aggression; when threatened they tend to retreat. It has been observed that females will attempt to protect their young calf from predators with their tail.

Manatees like to play! They are agile and graceful swimmers that can swim vertically, upside down, can do rolls, and perform aquatic somersaults.

View a video of manatees swimming living life (0:05 - 3:00):
Mating and BirthThe manatee mating system has been termed a "scramble competition polygamy". This means that females can be pursued by up to 20 or more males when mating. Females are not mature until 5 years of age, while males mature around 9 years of age. Although mature, males may not be able to secure mating rights. They may have to wait until the are physically larger; for manatees, size matters. Manatees do not have pair bonding, so they do not have one mate for their entire life.
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Females give birth every 2 ½ to 3 years. This is due to the long gestation period for females, which is 1 year. Males play no role in caring for the new born calf. It takes another year to year and a half for calves to be weaned from their mothers.








IntelligenceIn the past, scientists have viewed manatees as being unintelligent animals. This is mostly due to their relatively small brains as compared to their relatively large bodies. These assumptions are beginning to be refuted by manatees in captivity. They are capable of understanding discrimination tasks, performing experimental tasks in order to receive treats, and demonstrate advance long term memory. These capabilities are similar to those of dolphins, which are considered highly intelligent.

Communication
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Three manatees communicating with each other



Communication has not been well-studied, but scientists have determined that the sounds emitted from manatees are not used for navigational purposes. Manatee vocalizations can sound like chirps, whistles, or squeaks and may express fear, anger, or sexual arousal. Vocalizations are much more common among females and their calves.






PredatorsThe young and weak are the most vulnerable to natural predators. These predators include alligators, crocodiles, sharks, and whales. The role predators play in the manatee's daily life is dependent on the living locations of both the predator and the manatee. The manatee can also die from natural causes, such as cold stress, gastrointestinal disease, pneumonia, and other diseases. Manatees like warmer water, but higher water temperatures have caused an increase in toxic algae blooms. A Red Tide in Florida killed more than 150 manatees in 1996.
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Manatee with propeller scars

The biggest threat for the manatee comes from HUMANS. The leading cause of death among manatees comes from fatal collisions with watercraft (especially speeds boats and their propellers), commonly referred to as boat strikes. Manatees can be crushed or drowned in man-made canal locks and flood control structures. Habitats are being destroyed through water pollution and residential development along rivers and waterways. In the past, manatees were hunted for recreation, oil, and their skin. They are still being hunted today in parts of the Caribbean and South America for food.

Endangered Species in the United States
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Poster for Save the Manatee Club
Manatees are one of the most endangered species in the world. As of January 2011, there were only 4,480 manatees living in the United States. In 1967, the West Indian Manatee was placed on the US Fish and Wildlife Endangered Species List with the status "endangered". In 1970, the Amazonian Manatee was placed on the list with the same status, while in 1979 the West African Manatee was placed on the list with the status "threatened".Under federal law, the manatee is protected by the Marine Mammal Protection Act of 1972 and the Endangered Species Act of 1973, which states that it is illegal to harass, hunt, capture, or kill any marine animal. Under state law, manatees are protected by the Florida Manatee Sanctuary Act of 1978.



Conservation Efforts1. Areas with laws for slower boat speeds in known manatee living areas2. Manatee Sanctuaries
    • First manatee refuge was established in 1948 in the Florida Everglades
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      Sign in Florida indicating slow boating speeds in manatee zones
    • These sanctuaries are off limits to human activity
    • They are areas in which it is known that manatees can feed and rest without being disturbed
    • 7 Federal sanctuaries in Florida have been established
3. Rescue and rehabilitation of injured or sick manatees and then returning them to the wild.






Text Sources
1. "Manatee" National Geographic. 11 Nov 2011 <http://animals.nationalgeographic.com/animals/mammals/manatee/?source=A-to-Z>
2. "Manatee" A-Z Animals. 20 Nov 2011 <http://a-z-animals.com/animals/manatee/>
3. "Florida Manatee" Defenders of Wildlife. 11 Nov 2011 <http://www.defenders.org/wildlife_and_habitat/wildlife/manatee.php>
4. "Manatee Facts" Save the Manatee Club. 11 Nov 2011 <http://www.savethemanatee.org/manfcts.htm>
5. "Manatees" The Magnificent Manatee. 11 Nov 2011 <http://www.manatees.net/>
6. "Manatees Are Much More Intelligent Than Previously Thought" Softpedia. 21 Nov 2011 <http://news.softpedia.com/news/Manatees-Are-Much-More-Intelligent-Than-Previously-Thought-39923.shtml>
7. "All About Manatees" Virtual Explorers. 25 Nov 2011 <http://www.virtualexplorers.org/belize/belize_bkgd.htm>
8. "Interesting Facts About Manatees" 25 Nov 2011 <http://www.buzzle.com/articles/interesting-facts-about-manatees-sea-cows.html>
9. "Environment Conservation Online System" US Fish & Wildlife Service. 20 Nov 2011 <http://ecos.fws.gov/speciesProfile/profile/speciesProfile.action?spcode=A007>
10. Lowe, D.W. & Matthews J.R. (1990) The Official World Wildlife Fund Guide to Endangered Species of North America Vol. 1
11. Grzimek's Animal Life Encyclopedia 2nd Edition Vol. 15 (2009)

Media Sources
1. http://www.clickrally.com/tea-partiers-target-manatees/
2. http://www.portlandpua.com/2010/12/mermaid-theory/mermaid-and-manatee/
3. http://animals.nationalgeographic.com/animals/mammals/manatee/
4. http://www.youtube.com/watch?v=GzGSAs3dcTI&feature=related
5. http://www.visualphotos.com/image/2x2698699/manatee_eating_lettuce_underwater
6. http://www.youtube.com/watch?v=p7txP9MOCqs
7. http://www.savethemanatee.org/repro.htm
8. http://jpweddingphotograpy.blogspot.com/2011/05/manatee-we-need-to-stop-destruction-of.html
9. http://scienceblogs.com/shiftingbaselines/2008/08/crystal_river_manatees.php