Marine mammals possess special bodily systems to allow them to survive 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.
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)