entirely in water.
Whales and dolphins represent the living group known as, "marine
mammals." These creatures are part of the mammal class because, just
like mammals on dry land, they give birth to and suckle their young,
use lungs for breathing, and heat their own bodies. However, since
they are mammals that live in the sea, their physical structures are
rather different to those of other mammals. They have special bodily
systems designed for living entirely in water, thanks to which they
are able to swim for many kilometres without tiring and to see
everything in the water and on land with the same clarity. (Harun
Yahya, The Design in Nature)
The Ability to See Clearly in Different Environments
The eyes of whales and dolphins permit them to see in very different
surroundings. Their vision is equally perfect beneath and above the
water. A dolphin, for example, can leap 6 metres above the water and
easily seize a piece of food held up for it in the air. Yet, most
living creatures, human beings included, are unable to see very well
outside their own habitats, due to differences in the refraction of
light. The difference between the eyes of marine mammals and
terrestrial mammals are astonishingly detailed. On land, the potential
dangers facing the eye are physical impacts and dust. That is why
terrestrial mammals have eyelids. In a water environment, however, the
greatest dangers are salt levels, the pressure arising when diving
down to great depths, and damage due to marine currents. In order to
avoid direct contact with the current, the eyes are located on the
sides of the head. There is also a hard layer that protects the eye
during deep diving. Since the bottom of the sea is in darkness beneath
a depth of 9 metres, the eyes of marine mammals have been equipped
with various features allowing them to adapt to the darkness. For
example, the lens is perfectly spherical. Light-sensitive rod cells
are more numerous than cone cells, which are sensitive to colour and
detail. In addition, there is a special phosphorus containing layer
inside the eye. That is why marine animals can see so well in the
dark.
The Miracle of Life in Salt Water
Mammals, such as whales and dolphins, that live in the sea require
fresh water in order to survive. Unlike fish, however, they do not
meet that need using salt water. These mammals meet the greater part
of their water requirements by eating other living things that contain
only a third as much salt as the level in the oceans.
For marine mammals, with such restricted water resources, it is of the
greatest importance that as much water as possible be stored and
preserved inside their bodies. The well-known scientific journal,
Scientific American, examined this important subject under the
heading, "How marine mammals drink salt water." In a statement in the
magazine, the marine biologist, Robert Kennedy, described how marine
mammals obtain the water they need from the food they consume. Kennedy
noted that marine mammals reduce the levels of salt in their bodies
and regulate the water in their blood by avoiding salty food particles
(Scientific American, July, 2001).
Research has shown that marine mammals are able to preserve the fresh
water in their bodies, thanks to solutions that are unique to them. In
order to avoid water loss, these creatures do not sweat since they
have no sweat glands in their skin. Their kidneys also reduce the
amount of water expelled in urine by maintaining a high level of urea
in the blood. Water loss is thereby reduced to a minimum.
Complex Mechanisms
These vital functions are obviously essential to marine mammals'
survival. However, it is impossible for them to have thought of and
discovered all these finely-tuned details of their own will. These
creatures possess no intelligence with which to choose what they will
eat or to maintain the water in their bodies. Even if they did possess
such intelligence, it would still be impossible for them to construct
the complex mechanisms in question inside their own bodies. All these
solutions, the product of intelligence, are signs of creation revealed
to us by science that we encounter in a great many living things.
There is no doubt that it is Almighty Allah, Lord of the Worlds, who
creates marine mammals and inspires them with how to maintain the
levels of water in their bodies.
The Interesting Way That Marine Mammals Sleep
How do marine mammals, that spend their entire lives in the water,
manage to sleep without drowning?
A team led by Bruce Hecker, director of the South Carolina Aquarium,
investigated the answer to this question and revealed two basic
methods of sleeping.
Marine mammals either rest silently in a horizontal or vertical
position in the water, or else sleep while slowly swimming alongside
another animal. Dolphins, which live alone, tend to sleep more deeply
and at night. This is known as "logging," because, in this state, the
dolphin resembles a log floating on the surface of the water. When
marine mammals sleep and swim at the same time, this is known as
"napping." Young whales and dolphins rest and sleep by being drawn
into the slipstreams created by their mothers, known as "echelon
swimming." At these times, the mother is also able to sleep while
moving. Adult male dolphins, on the other hand, usually travel in
pairs and swim side by side when sleeping. Females and youngsters
travel in larger groups, or pods. They are able to rest in the same
general area or else pair up with companionable animals to sleep while
swimming.
When sleeping, these animals shut down half of their brains, together
with the opposite eye. The other half of the brain remains awake at a
low level of alertness. This attentive side is employed to watch out
for predators, obstacles, and other animals. At the same time, it also
emits a signal telling the animal when to rise to the surface for
fresh air. After some two hours or so, the animal reverses the
situation, resting the attentive half of the brain and activating the
other. This model is generally referred to as "cat-napping." Dolphins
generally sleep at night, once, and for a period of only a few hours.
They are generally active during the later hours of the night,
probably matching this period of wakefulness to catch fish and squid.
There can be no doubt that it is Almighty Allah who bestows these
systems on marine mammals. Allah has created these life forms with the
ideal characteristics to permit them to survive. Our responsibility is
to have sure and certain faith in our Lord and to be able to see the
manifest evidence of His existence on Earth:
"And in your creation and all the creatures He has spread about there
are Signs for people with certainty."(Surat Al-Jathiyya,4)
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