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These animals can get rather complex so first I will talk about
the general basic concepts of a marine mammal and fish, then I will
give some interesting facts on the marine mammals.
Marine Mammals:
These animals evolved from mammals on land, making a return to
the ocean, some of their ancestors are elephants and other land
animals. Marine Mammals are governed under the same characteristics
that make a mammal, such as hair, warm blood, lungs, mammary glands,
live birth, and a hinged jaw. More specifically Marine mammals have
a way to keep themselves warm, and are highly adapted to swimming.
Fish:
The animals evolved in the ocean, and are highly adapted for life
in this environment. Some basic characteristics of fish in general
are gills, a swim bladder, and scales. Fish are the most diverse
group of vertebrates so this might be a good activity to but after
fish diversity.
Cetaceans:
These animals are highly streamlined for swimming with a thick
layer of blubber achieving this as well as warmth. They propel themselves
forward with an up and down movement of their tail. They live in
groups called pods, which have very interesting social structures.
These animals have been known to help keep a mother afloat when
she is giving birth, showing that they care about the well being
of one another. These animals used to be hunted vigorously for many
products that the humans used. This did not slow until some laws
were past. Yet, even now many are dying due to hunting, just not
of the cetacean, but rather fish, and these marine mammals just
happen to wander into their nets.
Toothed: These are the orcas, dolphins, and other toothed whales.
These animals are very intelligent and are often seen in shows,
there have been many case studies that show that these animals actually
do like human contact, such as coming back voluntarily to a dolphinarium.
They are smaller then their baleen counterparts, and are carnivorous
eating a wide range of food. Toothed whales also use echolocation,
which is a way for them to tell about their surroundings. These
also are relatively unique to each animal, each with their own sound
patterns.
Baleen: The larger whales, includes the largest animal on earth,
the blue whale whom happens to be a female. Some of these whales
have elaborate songs, most notably the Humpback whale, whom actually
passes down these songs from generation to generation. These songs
also change when going from pod to pod.
Manatees:
These animals live mainly along the coasts of Florida. Manatees
have no natural predators but are yet extremely endangered animals.
Their main problem is with human caused events, most notably the
speedboats. Although they can swim relatively fast because of how
shallow the water they graze on is, they can not dodge the fast
moving speedboats. There is a simple cure for this that is currently
trying to be enforced, which are propeller guards. An example is:
A navy fleet had a run in with a group of manatees and killed a
mother and her child. To prevent this from happening they installed
propeller guards on all their boats, and have not had any accidents
since. This makes the wound blunt instead of an actual cut, which
is much easier to recover from.
Sea Otters:
Sea Otters have a unique way of keeping warm; they have extremely
dense fur, 1,000,000 hairs per square inch. It is made up of two
different types of hairs, one type is the under hair which is used
for insulation, while the other type keeps the under hair dry. Their
hair also lacks erector pili which is what causes hair to be able
to stand straight up, this causes the hair to lay flat against the
body. One unique thing about Sea Otters is their use of tools, when
eating.
Sea Otters consume 20-25 percent of their body weight every day;
because of how much they eat fishermen consider them competition
and sometimes try to get rid of them. This is why they have created
'otter free zones' for the fishermen; so many people try to keep
them out of these areas.
Polar Bears:
This species arose from the brown bears, and are actually the largest
bears there are. They can get up to 800kg and over 3.5m tall. A
polar bear's fur is not white. Each hair shaft is pigment-free and
transparent with a hollow core. Polar bears look white because the
hollow core scatters and reflects visible light, just like ice and
snow does. Sometimes polar bears will actually turn green. This
is because of colonies of algae growing in the bears' hollow hair
shafts. It is thought that the algae form a symbiotic environment
with the bear, giving the bear warmth through photosynthesis and
the bear providing shelter. Humans sometimes hunted them, for the
meat, blubber, and fur. Also they have problems with wandering into
towns, which would kill them. They are highly adapted for marine
life, including webbed toes, and a thick layer of blubber. Polar
Bears exhibit an idea of self-awareness for when hunting on land;
they cover their nose with their paws, as well as squint their eyes
to prevent them from being seen. They have 1 to 2 cubs that they
care for, that stay for approximately 3 years each. They are considered
marine mammals because their entire lifestyle depends on the ocean.
Their main food source is seals and sometimes fish. Polar bears
are the world's largest land predators.
Pinnipeds:
There are 33 species of pinnipeds; these range from sea lions,
seals, to walruses. In general pinnipeds tend to prefer colder waters.
Though they come on land to breed, molt, warm, and rest. They are
highly streamlined because of their blubber. The walruses have tusks
and are more similar to sea lions then seals. They can be up to
5m long, and have tusks, which can be used for a variety of things
including mating battles and freeing ice. Some of the problems that
these animals have to face are humans hunting for them, as well
as pollution going into the oceans. There are some rather big differences
between seals and sea lions from these groups that are not often
recognized. These are a few basics:
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Seals
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Sea Lions
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Swim with hind flippers, which are completely furred.
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Swim with fore flippers, which have naked soles.
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Can be freshwater or marine
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Exclusively marine
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Drag bodies while on land
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This group is much more able bodied on land, and are commonly
seen in shows.
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