The Manatee

Grace Krieger

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Integumentary System

Manatees have tough, elephant-like skin. It is made mostly of collagen. Even though their skin is grey, it can appear brownish-grey. Since they are slow moving animals, algae may collect on their skin and confuse the color making it greenish-brown. Underneath that, Manatees contain thick layers of fat. This is for warmth and it also allows them to float. Manatees also have sporadic hairs on their body, the hairs are most abundant on their snout.
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Skeletal/Muscular System

While our human skeleton allows us to use tools and do things on land, a manatees is for swimming with its frame that creates a stream-line body shape. The manatees body ends in a flat tail, otherwise known as a fluke Like whales, dolphins and other mammals, the manatees fluke go in a up and down motion to propel the animal in an extremely powerful fashion. This is unlike its aquatic friends, such as fish, who have side to side motions to allow them to swim. Helping the manatee to crawl, otherwise known as propel, navigate through depthless or obscured waters, and allowing it to get food into its mouth, or touching, holding onto other manatees or other objects are just some of the many helpful uses of the manatees powerful flippers. Manatees ribs and other long bones have a lack of marrow cavities, thus the animal having a heavy skeleton. The marrow in the manatee is confined to the bodies of the vertebrae and the sternum. The manatees small hip bones and remnants of hind limbs are attachment sites for muscles; the muscles of this animal have barely any myoglobin, muscle hemoglobin, this means that manatees can't store a lot of oxygen so they preform short and shallow dives. The pelvic bones of the manatee are vestiges that are attachment sites for muscles. These vestiges represent their more elaborate and complex structured ancestors. Also, manatees don't have hind limbs, the two fore limbs, their flippers, are similar to our own human bones: upper arm (humerus), elbow (olacranon), fore arm (radius and ulna) and five jointed 'fingers' ending with nails. Now, with manatees only three to four of the nails extend from the manatee's thick skin of the flipper, which covers the fore limb bones.

The Nervous System

Like other vertebrates, manatees have two main divisions to their nervous system, central & peripheral. Although there extremely large size, manatees have a small brain; not only do manatees have a small brain, it has a smooth exterior, which is not common for a complex animal. The importance placed on certain regions of the manatee's brain are very distinctive. Sensory parts of the mid and forebrain that process information for the flippers, tail, & mouth area are larger than other parts. They have almost a sixth sense, manatees use small hairs on their body to pick up info about water currents, landscape, and the presence of other animals. This is found in fish, which monitor underwater surroundings through twin lines of sensory pores along their bodies. The parts of their medulla that have to do with their snouts and the sensory hairs there is also enlarged. Manatees see and hear well underwater.
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The Respiratory System

The manatee's nostrils are where they take in breath, when they go back underwater their nostrils automatically close off in order to keep the water out. They breathe on average every 2-5 minutes, yet they can stay submerged for 20 minutes. Manatees lungs are very special, their lungs are flattened and prolonged. They stretch horizontally along the manatees back, almost to the anus. This is unlike any other mammal, just like how the branching arrangement of the bronchi and blood vessels in the lungs is more simple in manatees that it is in other mammals. Another thing about their lungs is that each has its own independent cavity. They have two hemi-diaphragms; this differs from other mammals who have one diaphragm. The manatee's lungs help control their buoyancy. With every breath the manatee takes, they change/refresh 90% of the air in their lungs, whereas humans only change 10% of the air in their lungs. This feature allows them to make more use of their trips to the surface. Lastly, alike other aquatic mammals, when diving, manatees can slow their heart rates to as little as 20% of their ordinary rate. This is for the conservation of oxygen.

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The Circulatory System

Manatees have a closed circulatory with a four chamber heart, like humans and other animals. Their heart beats about 60 times per minute, and during longer dives they can reduce their heart rate to 30 beats per minute. A very important function for their system is to regulate body temperature/ transport heat by transferring heat from warm arteries to cool veins. They need to do this because they do not generate a lot of body heat due to their lack of fat etc. This mostly applies to Florida manatees, it is not unusual to die because the water temperature has dropped to even 70 degrees. With a combination of warmer waters and a well functioning respiratory system, the Manatee can survive.

Endocrine & Digestive System


  • Manatees are aquatic mammals, yet they don't include most water when they eat, resulting in their stomach contents being pretty dry. Manatees have large salivary glands to aid in digestion, like plant eaters.Manatees, like horses, are hind-gut digesters. This results in most of the digestive process occurring further along the intestinal tract. Their metabolic rate is 15-20% of what one would expect to see for a mammal of the manatees proportions. One can conclude from this that the manatee has a relatively poor diet. The manatee takes seven days to digest food.

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    Reproductive System

    Male manatees reach sexual maturity around 9-10 years of age, whereas females can reach sexual maturity. It is estimated that one calf is bonr every 2-5 years, and that twins are rare but do happen. The gestation period for a female is is about 12-13 months. The female manatees genital opening can be located just in front of the anus, and the male manatees genital opening lies just behind the navel, about halfway down the underside of its body.

    Works Cited

    "About the Circulatory System of a Manatee." EHow. Demand Media, 28 Oct. 2008. Web. 29 Nov. 2014.


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    "About the Circulatory System of a Manatee." EHow. Demand Media, 28 Oct. 2008. Web. 29 Nov. 2014.