When was the first manatee discovered

The Amazonian manatee Trichechus inunguis lives entirely in freshwater rivers throughout South America in the Amazon Basin. It is hard to estimate their numbers due to their secretive nature and the murky water where they often live. A fourth dwarf manatee species was described in the mids, but this claim was called into question and it is believed to actually be a juvenile Amazonian manatee. The main threat to this species is illegal harpoon hunting for subsistence.

Although they look similar to manatees, dugongs have a more whale-like fluke compared to the round, paddle-like tail that you see on manatees. The closest living relatives of sirenians are elephants. Manatees evolved from the same land animals as elephants over 50 million years ago and the fossil record shows a much more diverse group of sirenians than we have today, with dugongs and manatees living together throughout their range.

Humans have one round of baby teeth and then if we lose or hurt an adult tooth, a trip to the dentist is in order. Manatees, like their elephant relatives, continuously replace their teeth throughout their lives with the older teeth at the front falling out and new teeth growing in at the back of their mouth.

In , Georg Wilhelm Steller first described the sea cow from islands off the coast of Russia in what would later be called the Bering Sea as subsisting off of kelp and not being able to submerge underwater. Within 27 years of first being described, the species was driven to extinction by hunting and competition for their kelp food source with an exploding urchin population.

Christopher Columbus and other early explorers claimed to have seen female figures swimming in the ocean—the mermaids in the writings and drawings of this era. Whether they had been at sea for too long or it was a trick of the light, we now know that many of these encounters were with manatees.

Manatee brains are smooth compared to our own that have the familiar ins and outs of cortical folds and the ratio of their brain to their body size is the lowest of any mammal. They may not be as clever as dolphins, but manatees can learn basic tasks, are extremely sensitive to touch and can differentiate colors.

Female manatees usually have one calf every two to five years and the calf then stays and nurses for two years. The manatee swims with slow undulations of the body and tail. Manatees are in fact so slow and leisurely, that many of them have algae or barnacles growing on their backs.

For this tropical fish, the algae on a passing manatee is lunch! The two flippers of the manatee are used to steer and position the manatee while swimming, but they are also used as arms to hold onto objects and manipulate food to the mouth. They can use the flippers to grab people if they are feeling playful. Sometimes the manatee even "walks" on its flippers. The evolutionary relationship of manatees to land animals is perhaps most obvious in the flippers, which still retain the finger bones of distant ancestors, even though the fingers themselves have long since been lost in order to form a flat paddle shape.

The manatee has small eyes, protected by membranes which can be drawn across the eyeballs. The manatee is capable of seeing in both dim and bright lighting, and can probably see colors, but has somewhat limited depth perception. It produces thick, sticky tears to protect its eyes when they are out of the water. Although the manatee lacks eyelids as we know them, it can still blink to protect its eye. The ears of the manatee are internal, with no external lobes, but the underwater hearing of the animal is quite good.

Manatees produce squeaks and chirps. It is not known for sure why, but it is suspected that they could range from alarm calls, to expressions of happiness. Most scientists believe that the manatee does not use these sounds for echolocation like a dolphin would.

Breathing occurs through a pair of nostrils located on the top of the nose. The manatee can close off its nostrils when diving in order to keep water out. This allows the manatee to make more efficient use of its trips to the surface. Manatees normally breathe every 2 to 5 minutes, but can stay submerged for as long as 20 minutes if necessary.

The mouth of the manatee contains rows of molars, for chewing the tough plants which make up the animal's diet. As these teeth are worn down by the plants, they are replaced with new ones growing in from the back. For the entire life a manatee, it never runs out of new teeth!

There is sand in the plants the manatees eat and it wears down the teeth. The front teeth are more worn, while the ones in the back still have a bit of a point to them, and the teeth go right down inside the jawbone.

The manatee is a simple and docile grazer. It has evolved no defenses because it has no natural enemies, and eats only aquatic plants. In fact, it is the only completely herbivorous marine mammal in the entire world.

Manatees prefer shallow water, between 6 and 7 feet deep, where they can find their favorite foods. The nutritious roots of water plants, especially the water hyacinth, are a manatee favorite. Since this proliferating water weed is a nuisance to people, weed chomping manatees are natural weed-control agents!

Manatees are, in fact, so effective at eating their way through weed-choked canals, that they have actually been employed in some countries to clear canals for people.

Unlike the cow, which does most of the digestion in the stomach, manatees are more like horses, having a long colon for digestion. It takes hours for food to pass through the manatee digestive tract. Jesse R.

White, Marine Mammal Veterinarian. The manatee needs to drink water in addition to eating. When in fresh water, this is not a problem, and the animal drinks frequently. However, when the manatee is in the ocean or brackish coastal areas, it cannot get fresh water to drink. In addition, the manatee inadvertently swallows some sea water when it feeds in these areas. The kidneys of the manatee are specially developed to help it rid itself of excess salt.

But it is not known how long a manatee can go without fresh water. When manatees aren't eating, they either sleep, or play. When sleeping, the manatee lies motionless on the bottom, but has to surface for a breath every few minutes. Collins, Colorado. Domning, D. Interspecific and intraspecific morphological variation in manatees Sirenia: Tricechus. Marine Mammal Science 2 2 : Evolution of manatees: a speculative history. Journal of Paleontology. Flamm, R. Aerial videogrammetry from a tethered airship to assess manatee life- Stage structure.

Marine Mammal Science. Marsh, H. Heinsohn and L. Breeding cycle, life history and population dynamics of the dugong. Dugong dugon Sirenia: Dugongidae. Australian Journal of Zoology. Beck, and T. Comparison of the capabilities of dugongs and West Indian manatees to masticate sea grass.

Evaluating management initiatives aimed at reducing the mortality of dugongs in gill and mesh nets in the Great Barrier Reef World Heritage Area.

McClenaghan, L. Genetic variability in the Florida manatee Trichechus manatus. Journal of Mammalogy. An analysis of manatee mortality patterns in Florida, Journal of Wildlife Management. Smith, A. Environmental Magazine. Stejneger, L. How the great northern sea cow Rytina became exterminated. The American Naturalist. Fish and Wildlife Service. Florida manatee Trichechus manatus latirostris recovery plan.

By the Florida manatee recovery team for the U. Fish and Wildlife Service, Atlantic, Georgia. Dietz, Tim. The call of the Siren: Manatees and Dugongs. Fulcrum Pub. Golden, CO. Reynolds, John E. Facts on File. New York. Ridgeway, Sam H. Academic Press. Orlando, Florida. Tate, Suzanne. Nags Head Art, Nags Head. Book a Program. Help DRC. Donate Now. Gift Memberships. Donations and Special Appeals. Greeting Cards. Major Giving. Bucket of Fish.

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