HOW DO FISH LIVE IN WATER?
You must have seen how fast and brisk fish are in water. In order to swim, a fish does not need to make any movement other than to wag its tail from side to side. This ease of movement that fish have in water is thanks to their flexible backbones as well as some systems in their bodies.
A fish expends a large amount of energy while swimming. This is not because it swims fast for long times. Fish need considerable amounts of energy in order to reach high speeds from being still. It is vital for a fish to gain speed instantaneously because it needs to do so in order to escape from predators.
Moreover, fish move against the current most of the time. Consider how hard it is for you to move in water and how easy it is to move while you are walking in the street. Compare living underwater and living on the face of earth.
In the creation of the heavens and earth, and the alternation of the night and day, and the ships which sail the seas to people's benefit, and the water which Allah sends down from the sky - by which He brings the earth to life when it was dead and scatters about in it creatures of every kind - and the varying direction of the winds, and the clouds subservient between heaven and earth, there
are Signs for people who use their intellect.
(Surat al-Baqara: 164)
It is the special structure of the backbone and muscles of the fish that provide it such power. The backbone keeps the body straight and is connected to the fins and muscles. Otherwise, it would not be possible for the fish to move in the water. However, the particular shape of the backbone is not sufficient to enable the act of swimming. That is because fish not only move forward and backward, but also upward and downward in order to survive. This movement is made possible by another system in their bodies. Fish have air sacs in their bodies. By emptying these sacs of air, fish can sink to the bottom of the sea, and by filling the sacs with air fish can rise to the surface again.
The picture on the left shows the remains, in other words a fossil, of a fish that lived a very long time ago. Another member of the same species, one that is still alive today, can be seen in the picture below. As you can see, there is no difference between the two.
Have you ever wondered how fish are not damaged at all although they are always in the water? Our skin becomes affected if we stay in water for a while; if we stay for a longer time then our skin becomes injured. But this never happens to a fish. This is thanks to a stiff bright layer in its outer skin. This layer prevents water from entering its body. If fish did not have this layer, their bodies would be damaged, and since water would enter the body the balance would be disturbed and they would eventually die. However, these do not happen and all fish continue to live their underwater lives.
All fish species in the world possess these features. Species that lived long ago possessed them too. Fish have had the same perfect structure for millions of years and have not gone through any change. It is possible to see this in the remnants of fish that lived millions of years ago. These remnants, namely fossils, clearly reveal that fish were the same as they are today and have not changed at all. This is evidence that fish came into existence at one point in time. In other words, they were created. It is Allah Who gave fish all the features they have and Who created everything in the universe. He knows the needs of all creatures.