Реферат на тему Manatees Essay Research Paper ManateesQuietly but swiftly
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Manatees Essay, Research Paper
Manatees
Quietly, but swiftly, the plump, dark animal glided across the water
while making sounds comparable to that of the squeaks and squeals of a whale
(”Florida Manatee” 1). Some would say these aquatic mammals are the ugliest
thing below the surface, others would say that these animals are beautiful and
resemble portly mermaids, but no matter what anybody says about the manatees,
they are unique creatures (Ray and Ciampi 315). They are mammals that are
completely harmless, they feed mostly on sea grass and sometimes small
underwater creatures like shrimp (Berrill 212). It is a shame for these
creatures to be on the endangered species list.
Looking at the physical aspect, these animals are incredibly uncommon,
and like no other creature on earth. These majestic beasts can float across the
water amazingly fast for its size (”Florida Manatee” 1). They can weigh up to a
ton, and get as long as fifteen feet. They are almost devoid of hair, except for
some whiskers on their face, and they have internal ears on the sides of their
head. Their nostrils are closed by valves, so they can accomplish such feats as
flips and quick turns without losing any air. Manatees have no hind legs, but
instead one big, flat, spatula-like tail (Sentman 327). This feature made people
confuse manatees with mermaids for nearly four centuries (O’Shea 66).
Many biologists say that manatees possibly originated or evolved from
ungulates such as elephants and cows because of the way that they are built, and
certain features that they have in common. Like elephants, manatees have the
peculiar half-moon shaped fingernails, and thick, wrinkled skin. Manatees also
shares some traits with cows. The way the manatees spend all day lazily grazing
on the ocean floor is incredibly similar to the behavior of cows at a pasture
(Breeden 58).
Manatees eat an outrageous amount of food, they consume approximately
ten percent of their body weight daily. The large quantities that the manatees
eat is another one of its unique qualities (”Florida Manatee” 1). People use the
manatees as natural “underwater lawn mowers”, setting them free in lakes that
have too much sea grass or plants. The manatees consequently eat up the
vegetation, which frees up space to allow other wildlife to inhabit the lake.
Manatees are also used to clear up canals and irrigation rivers that are clogged
with an extreme amount of aquatic plants (”Manatee Facts” 1). The large diet can
also be a disadvantage. With the amount of vegetation in manatee habitats
decreasing tremendously, the manatees are in danger of starving to extinction.
The underwater plants do not survive because of man’s harmful deeds such as
pollution, erosion caused by deforestation, and draining wetlands for the
building of coastal homes. Since the 1970’s, in Tampa Bay alone, eighty percent
of sea-grass beds have vanished due to these causes (O’Shea 68).
Manatees can also be silly and clumsy at times, they have very bad
eyesight and do not have the attribute of sonar or echo location that some
underwater mammals have. This causes them to occasionally bump into large
underwater rocks and other submerged objects. The poor navigational abilities of
the manatee is an obvious disadvantage. A fast oncoming boat may not be seen by
a manatee until it is too late (”Manatee Facts” 1).
Manatees are mainly solitary animals, they graze alone and do not travel
in groups. Although sometimes, manatees may be seen in temporary groups in which
they will socialize, and leave at anytime. They communicate mostly using faint
whistles and squeaks, but some biologists speculate that they use scent marks to
mark their location like some land mammals. Newborn manatees will also stay with
their mother for at least a year, and will recognize her for the rest of its
life. If needed, nursing females will adopt a manatee calf that is not its own
(O’Shea 70). This type of social behavior shows that manatees are extremely
peaceful, and very friendly.
They are also very agile animals, moving at the normal pace of five
miles per hour. When provoked, they can burst to speeds exceeding fifteen miles
per hour. They also can perform various feats such as barrel rolls, somersaults,
head stands, and gliding upside-down (”Florida Manatee” 1). On the most part,
manatees can be found pasturing on the bottom of the ocean. They drift around
very slowly when doing this activity, and are usually unknowing of anything else
taking place around them. This can leave them greatly vulnerable to poachers,
and irresponsible boatmen (Berrill 212).
There are three different types of manatees, the West African, Amazonean,
and the Caribbean. The differences between the three are slight physical changes,
and habitat. The larger, and more recognized of the three is the Caribbean or
West Indian manatee, which lives off the southeastern coast of the United States.
All three kinds of manatee species live in tropical or sub-tropical climates,
and all three species have legends, or myths linked to them.
The West African manatee is noted by a tribe in Mali, they thought that
killing a manatee without permission from the gods would give them a curse, and
only trained wise-men could perform this task. The Caribbean manatee was
recognized when Christopher Columbus sailed to the Indies, and described them as
mermaids in his journal. Lastly, the Amazonean manatee is noted by the Central
American Siona Indians in a very unusual story. The Siona Indians believed that
an ancient god was deceived and trapped by a tapir, a horse-like animal. The
tapir then subjected the god to attack by piranhas. In revenge, the god turned
one of the tapir’s daughters to live forever in the water as a manatee (O’Shea
68).
The manatees’ heritage can also be traced by its name. For instance,
their mammalian order, Sirenia, is given that name because of the sound that
they made (”Florida Manatee” 1). Sailors mistook their sounds for the sounds of
Sirens, characters in Greek mythology who had the bodies of birds, and heads of
women. In the myth, the Sirens had such voices of sweetness that they lured
sailors to drive their boat onto rocky shores (”Sirens” 1). Their name, manatee,
comes from a Carib Indian word for a woman’s breast. This is because the nipples
of a female manatee are very prominent. They are located on the sides of the
manatee, and it can be clearly seen from the surface (McClintock 45). Their
common nickname, the sea cow, originates from an extinct species called the
Steller’s Sea Cow. The Steller’s Sea Cow is in the same family as the manatee,
and used to inhabit the frigid waters of the Bering Sea. The sea cow name lives
on, while the original sea cow does not (”Sea Cow” 1). The nickname was passed
to the manatees because of their relation with real cows.
Unfortunately, the Manatees presently face many problems, even with
protective laws passed by the US government. Careless boaters are the manatees’
worst enemy, countless occasions have resulted in the boat’s propellers slicing
through the flesh of the manatee, and death usually occurred. If the victim
manatee did not die, then they have lifetime propeller scars on their back. This
is a shame because it can be avoided very easily, and it happens to helpless
animals like the manatee. Other things kill manatees also, like herbicidal spray,
flood control dams, and worst of all, illegal hunters. These present day killers
murder approximately 100 manatees a year (”Manatee Facts” 1).
However, these numbers are minuscule, compared to the commercialized
hunting of the manatees back in the late 1950’s. As a many as 7,000 manatees
were killed in a year because of this commercial hunting. Fortunately the
hunting slowed to a halt in the 1970’s because humans had begun to realize the
impact that they were having on the manatee population (O’Shea 68).
Not considering humans, manatees have almost no natural predators, but
sometimes manatees may be killed by what they eat. Manatees consume a wide range
of aquatic plants, including algae, which may contain brevetoxin. Brevetoxin is
a bacteria that kills many aquatic animals including fish, and apparently
manatees. Brevetoxin is usually found in a type of reddish-brown algae called
the red tide. Last July, the bacteria alone killed 304 manatees creating a new
official record for most manatees killed in a year (”Toxin Killed Manatees” A18).
Aside from Brevetoxin, the manatees only natural predator is its unawareness,
they sometimes drift too far north, and get killed by the cold sea water. This
is a problem that whales and other large sea mammals also have to face. (O’Shea
68)
Having been studied seriously only since the mid 1900’s, manatees are a
fairly new creature in the science community. This is probably because that
manatees are very timid creatures which makes them hard to analyze. Still, not
much is known about the manatees to this present day. We do not know basic
fundamental facts such as where they go in the warmer climates, exactly how long
they live, and most importantly, precisely how many manatees are in existence
today (Breeden 58). The lack of knowledge does not mean that steps are not being
taken to study these animals. Recently, researchers attached satellite
transmitters to the manatee so that scientists can study their movement, and
speed. They have learned many new things from this study, such as that they can
travel up to fifty kilometers a day, and go back to a designated location every
season.
Further developments in manatee research will help in preventing the
accidental death of many of these animals. The research that scientists have
learned from the transmitters will help in regulating boat speeds in certain
areas to avoid the propeller deaths of many manatees, thus decreasing the death
toll. The research will also designate specialized places to guard manatees,
these areas will be watched very carefully by the US Fish and Wildlife Service
(O’Shea 71).
Scientists have no clue as to the manatee population before the
commercialized hunting of the 1900’s, therefore, people do not know how large an
impact man has made on the manatees. Even without the statistics, or the exact
numbers of manatees killed by humans in the past, we still know that man has
caused most of these deaths (Breeden 58). Whether it be by hunting, or
accidental incidents, man is the manatees’ worst enemy. To the average person,
manatees may not seem important but they are essential to many living things,
including humans. Manatees have ch
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