HOW DO FISH LIVE IN WATER?
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
are Signs for people who use their intellect.
(Surat al-Baqara: 164)
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.
HOW DO MACAWS KNOW CHEMISTRY?
You have read in this book that
macaws feed on rocks that contain clay, as seen in the
picture. If you had seen this picture before reading this
book, the behaviour of this parrot species would have
surprised you. Maybe you would not even have understood
what they were doing. But now you know why macaws eat
clay. Most importantly, you know that Allah teaches them
to do so. Tell others about what you have learnt to enhance
their faith in Allah as well.
Some plants have poisonous seeds.
This is an effective method of protection against their enemies
who try to eat them. Yet a parrot species living in America
can feed on these poisonous seeds. This is quite surprising
because while other creatures cannot approach the seeds, these
birds that continually eat them are not affected at all. You
are curious about how this happens, aren't you?
How this parrot species called
the macaw is not poisoned has attracted the attention of scientists
too. Scientists observed macaws and witnessed a quite extraordinary
pattern of behaviour.
Having eaten these nutritious
but poisonous seeds, macaws fly towards a rocky place. There
they gnaw upon and swallow some clay containing rocks. This
is not a random behaviour. Indeed, rocks that contain clay
absorb the poison of the seeds. This is how the macaw can
digest the seeds without suffering.
How has this bird acquired the
medical knowledge to diagnose the poisonous effect of the
seed? How does it know how to get rid of this poisonous effect?
Could it possibly have had an education in pharmacy to know
that a substance that neutralises the effects of the poison
is available in rocks that contain clay? Of course not.
A human being could not understand
whether a seed is poisonous or not by its appearance. He could
not estimate how to neutralise the effects of the poison.
In order to be able to do that, he would have needed education
or to have consulted those with knowledge. This being the
case, it cannot be claimed that a bird with no intellectual
faculties might have discovered such a thing after long chemical
analyses and study. It is not possible for macaws to acquire
this knowledge, which can be learnt by human beings only after
years of special education, by chance. All-Knowing Allah,
Who creates everything perfectly, teaches macaws this knowledge.
Have they not reflected within
did not create the heavens and the earth and
everything between them except with truth and
for a fixed term. Yet many people reject the
meeting with their Lord.
(Surat ar-Rum: 8)
ENGINEERING IN THE COBWEB
you ever noticed the shapes of spider webs? Did you know that
spiders produce their thread themselves and that this thread
has some amazing characteristics? Or have you heard that the
techniques used by garden spiders to spin a web are the same
as those used by civil engineers today?
A spider needs two separate
places in order to spin its web. Webs are generally spun in
a corner where two walls join or between two branches. However,
some spiders are so skilful that they spin their web using
a single surface. How a spider spins its web is spectacular.
Now try to visualise what we will tell you here.
spider first finds a flexible branch that is long enough to
spin its web. It firmly fastens a thread to the end of the
branch. Walking down the branch, it continues to secrete thread.
Once it covers a certain distance, it stops and ceases to
secrete. It pulls the thread it has secreted until the branch
is bent like a bow. The spider sticks the other end of the
thread, which is now as straight as a string, firmly to that
point. Then it starts to spin its web inside this bow.
Now consider what you would
do if you were to stretch a string two and a half metres long
between two walls that are two metres apart from each other.
While you are trying to find out how, let us explain how a
species of garden spider has solved this problem.
spiders sometimes spin their web between two distant branches.
Since such webs are quite large, they have a high capacity
to catch prey. Nevertheless, their large size results in a
gradual decrease in the tautness of the web, which means a
decrease in the ability to catch prey. So spiders need a solution.
You might have thought that the spider would spin a new web
once the web is not taut enough any more. But instead of replacing
the web the spider does something amazing: It secretes a thread
from the centre of the web down to the ground, and fixes a
small stone on to that end of the thread which is close to
to the web and pulling the thread, it lifts the stone. Then
it fastens the thread, at one end of which the stone swings
in the air, once again on the centre of the web. Consequently,
the web is taut again as the weight of the stone hanging from
the web stretches it down.
You would probably not come
up with such a solution neither would many people who do not
have knowledge of construction. However spiders know and apply
this technique. How does a spider know such an admirable technique
and apply it so well? Moreover, every spider has spun its
web applying the same technique for millions of years. There
needs to be an "Authority" Who inspires the spider to use
this technique because the authority to do it does not belong
to the spider itself. This power belongs to the Almighty Allah,
Possessor of everything, Who guides and inspires all living
creatures with what they should do.
AN INTERESTING CREATURE:
You must have seen submarines
on TV or in journals. These vessels, which are capable of
operating far below the surface of the sea without being noticed,
are used in ensuring national security and in some scientific
research. How submarines operate is: As the special diving
tanks in a submarine are filled with water, the vessel becomes
heavier than water and sinks deep down in the ocean. If water
in the tank is emptied and replaced by pressurised air, the
submarine rises up to the surface of the water again.
You have noticed that there
is no difference between the fossil of a nautilus that
lived a long time ago (below) and the nautilus of our
day, haven't you?
Now we will examine the nautilus,
a very interesting creature that employs exactly the same
method. The nautilus has a spiral, pearly-lines shell and
dives as submarines do. It has an organ shaped like a snail
shell that is 19 cm (7,5 inch) in diameter, as shown in the
picture. This organ contains twenty-eight interconnected "diving
chambers". These diving chambers operate in the same way as
the tanks in a submarine do; in other words the nautilus needs
pressurised air. In submarines, this need is met by a special
system established by engineers in relevant places in the
submarine. But how does the nautilus find the pressurised
air necessary to expel the water?
The answer to this question
introduces us to another amazing feature that Allah created.
A special gas is produced in the nautilus' body. This gas
is conveyed to the chambers through its bloodstream and eventually
expels the water from the cells. So a nautilus can sink or
float to protect itself against its enemies while hunting.
In fact the diving capacity of the nautilus is much higher
than that of a submarine. A submarine dives only to 400 metres
(1310 feet) while it is so easy for a nautilus to dive to
4,000 metres (2,5 miles).
The special system of this interesting
marine animal is created for us to reflect on it. Now consider
for a moment. Could a nautilus have attained this system by
chance? Could it itself have acquired the bodily structure
that enables gas production? Furthermore, this is not the
only feature of the nautilus. The pressure underwater is quite
intense. This is why you feel pressure in your ears when you
dive deep. Nevertheless the pressure you experience is comparatively
low; as one descends further in the water, the pressure increases
and after a certain depth has deadly effects on living creatures.
However, although it is a very small being and has only an
external shell to protect itself, the nautilus is not affected
by this pressure, which can be extreme.
… My Lord encompasses
all things in
His knowledge so will you not pay heed?
(Surat al-An'am: 80)
Obviously, all features that
a nautilus has are designed. This being cannot possibly on
its own design the bodily structure to resist a pressure of
tons underwater. Allah, Who originates everything perfectly,
designed this excellent structure. In a verse of the Qur'an,
Allah invites people to be heedful:
Is He Who creates
like him who does not create? So will you not pay heed? (Surat
BUTTERFLIES THAT HAVE KNOWLEDGE
appearance of butterflies is admirable. These creatures, which
with their colourful wings and elegant flight are like living
ornaments, are some of the sources of beauty that Allah creates
for us. However, a marvellous appearance is certainly not
the only feature of butterflies. These short-lived creatures
sometimes do calculations such as a specialist would do. For
example, like the moths which we discussed earlier, the body
heat of a butterfly should be at a certain temperature in
order for it to fly. Let's see what butterflies do to solve
colias butterfly cannot fly when its body temperature is below
28oC (83oF). In such cases the butterfly
opens its wings to expose its upper side to the sun and to
soak up the sun's rays at the correct angle. If its body temperature
rises as high as 40oC (104oF), it rotates
by 90 degrees and thus receives the sun's rays horizontally.
With this behaviour the butterfly absorbs as little heat through
the wings as possible and its body temperature decreases.
Besides that, this butterfly
species has little dark spots on its wings. These spots, the
function of which is to maintain a higher body temperature,
are not located in an unspecified place. They are close to
the points that are most needed to be warm. Thanks to this
particular design, heat transmission from these spots, which
warm quickly, to other parts of the body is facilitated since
the distance that needs to be covered to transmit heat is
butterfly species employs a similar method to increase its
body temperature. You all know what a lens is. Some are used
to produce enlarged images whereas some others are used to
produce smaller images of objects. For example glasses consist
of a pair of lenses. Besides this function, a lens angled
correctly toward the sun can concentrate the sun's rays on
a certain spot. Using this method it is possible even to light
a fire. The pieris, another butterfly species, angle its wings
toward the sun so that all rays are concentrated on certain
parts of its body that need most to warm, in a similar way
as a lens functions.
Certainly these butterflies
have not had an education in physics or in any other field.
They cannot know about the features of a lens. They do not
know which angle would receive the greatest amount of heat.
Allah, Who watches over and protects all things, inspires
in butterflies what they should do to regulate their body
temperature. As Allah reminds us in a verse:
… Allah is
watchful over all things. (Surat al-Ahzab: 52)
MALE CATFISH ON DUTY
is not generally known that fish build nests and provide continuous
protection for their offspring. These nests are generally
holes dug among pebbles or in the sand. Eggs develop in these
open nests for some time, during which the mother and father
fish take turns to keep watch over the nest for enemies.
Catfish are among these creatures
that protect their young. Female catfish spawn eggs at the
bottom of plants and reeds in shallow water. Eggs cling to
the roots of these plants. After a while, the female leaves
her eggs and then it is the male's turn to take on the duty.
The male's duty is to stay with the eggs and to keep watch
for danger. This sentry duty lasts for about 40-50 days after
which the young fish become fully mature.
Besides this vigilance, the
male also makes a murmuring sound using his gills and in this
way keeps other hostile fish away from the eggs. He knows
that this sound will threaten other fish and will force them
to go away.
Allah inspires male catfish
to protect their young in this way. Like all creatures, this
fish acts only in the way that Allah inspires in it and thus
ensures the continuance of its species.