Reactive Swimming Systems
receive great help during hunting from the tentacles in its
mouth. These whiplike tentacles normally remain coiled in
pouches beneath its arms. When the fish encounters a prey,
it unleashes them and snatches up the prey. The fish relies
on its adequately designed arms (eight in total) to take care
of the rest. It can easily tear a crab to bits by using its
beak. The cuttlefish uses its beak with such mastery that
it can neatly puncture the shell of a crab and rasp out the
meat with its tongue.36
Vertebrates are the fastest running, best swimming and farthest flying
creatures on earth
. The main factor underlying all of these abilities is the presence of
skeletons made of hard materials such as the bones that do not lose their
shape. These bones provide tremendous support for contracting and flexing
muscles, which bring about continuous movements through moving joints.
However, invertebrates move at much lower speeds, in comparison with
vertebrates, due to their boneless structures.
Cuttlefish are invertebrates that do not have bones in their bodies despite
being called fish. They have extraordinary abilities to manoeuvre because
of a very interesting system.
Their soft body is covered with a thick mantle under which large amounts
of water are drawn and flushed out by strong muscles and that enables
them to escape backwards.
The cuttlefish whose scientific nomenclature
is Loligo Vulgaris are the smallest among their species.
Their reactive swimming system enables them to move at speeds
in excess of nineteen mph (30 km/h). 37
This mechanism in cuttlefish is highly complex. On both sides of the animal's
head are pocket-like openings. The water is drawn in through these openings
into a cylinder-shaped cavity inside its body. Then, it jets out this
water from a narrow pipe immediately under its head with great pressure,
which enables it to move swiftly in the opposite direction due to reactive
This swimming technique is highly appropriate in terms of both speed
and durability. A Japanese cuttlefish, called Todarodes Pacificus, in
their migration of 1250 miles (2000 kilometres) travel at about 1.3 mph
(2 km/h). For short distances, it can accelerate up to 7 mph (11 km/h).
Some species are known to exceed 19 mph (30 km/h).
The cuttlefish can avoid its predators through very swift movements as
a result of these fast muscular contractions. When their speed alone is
not enough for safety, they squirt a cloud of dense, dark coloured ink
that is synthesised in their bodies. This ink surprises their predators
for a few seconds, which is usually enough for them to escape. The undetectable
fish behind the ink cloud leaves the area immediately.
The defence system and reactive swimming styles of cuttlefish also work
for them during hunting. They can attack and chase their prey at high
speeds. Their immensely complicated nervous system regulates the contractions
and flexing necessary for their reactive swimming. Accordingly, their
respiratory systems are also in ideal condition, which provides the high
metabolism that is needed for the jet propulsion.
The cuttlefish is not the only animal swimming by means of a reactive
system. Octopuses also utilise this system. However they are not active
swimmers; they spend most of their time wandering over rocks and gorges
in the deep sea.
The cuttlefish also has radial and circular
muscles as in the octopus, but instead of the octopus' longitudinal
muscles there is a fibrous layer in the cuttlefish. This layer prevents
its body from elongation when both the muscles contract as well
as providing a sturdy base for the radial muscles.
The octopus bends its
body by contracting either one of the two longitudinal muscles,
which enables it swim in the water.
The inner skin of the octopus is composed of many layers of muscles one
on top of another. They constitute three different types of muscles called
longitudinal, circular and radial. These structures enable various movements
of the octopus by balancing and supporting one another.
Shown in the
figure are the jet propulsion cycle and sections of the cuttlefish.
The cycle begins with enlargement (1). The outside diameter of the
body is enlarged by 10% of the normal size, which increases the
volume of the mantle cavity by about 22%. Water enters from the
openings on both sides of the head passing through the funnel-shaped
pipe. When the maximum enlargement is reached, the diameter of the
body is reduced to 75% of normal size (2). Pressure in the cavity
suddenly increases and pushes the inner tap on the mouth of flushing-out
pipe, which closes the water intake. Nearly all the water (approximately
60% of normal body size) is forcefully expelled out through the
pipe. The body recovers its normal shape by the intake of water
(3). Any further contractions could easily harm the creature. The
jet propulsion lasts about one second and can be repeated 6 to 10
times in a row, including suction time. When swimming slowly the
body of the cuttlefish contracts to 90% of its original size.
When flushing water out, the circular muscles contract lengthwise. However,
since they have the tendency to maintain their volume, their width increases,
which would normally elongate the body. In the meantime, the stretching
longitudinal muscles prevent the elongation. The radial muscles remain
stretched during these happenings that cause the mantle to thicken. After
the jet propulsion, the radial muscles contract and shrink the length,
which causes the mantle to become thinner, and the mantle cavity to be
filled with water again.
||The eye structure of a cuttlefish is extremely
complex. It can focus the pupil by bringing the lens nearer to the
retina. It can also adjust the volume of light taken into the eye
by closing or opening the little lids beside the eye. The presence
of such highly complex organs in structures of two completely distinct
species such as humans and cuttlefish
cannot possibly be explained by evolution. Darwin also spoke about
this impossibility in his book.38
The muscular system in the cuttlefish closely resembles that of the octopus.
However, there is an important difference: the cuttlefish has a layer
of tendons, called the tunic, instead of the longitudinal muscles of an
octopus. The tunic is composed of two layers that cover the inside and
outside of the body just like the longitudinal muscles. In between these
layers are the circular muscles. The radial muscles are situated in between
these, in a perpendicular orientation.
||The reactive swimming systems, ink discharge-based
defensive methods, the acute vision and the colour changing skin abilities
that cuttlefish have are perfect examples of creation.
Under the skin of the cuttlefish
is arrayed a dense layer of elastic pigment sacs called chromatophores.
By using this layer, they can change the apparent colour of their
skin, which not only helps in camouflage but also acts as a way
to communicate. For instance, a male fish can take on a different
colour when mating than that it would take on when in a fight with
When a male flirts with a female, it
takes on a bluish colour. If another male comes by during this,
it gives a reddish colour to the half that faces the other male.
Red is the warning colour used during a challenge or an aggressive
A thin layer of skin that
surrounds the arms and the body further supports the reactive swimming
system of the cuttlefish. The fish floats in the water by means
of waving this curtain-like membrane. The arms, on the other hand,
function to balance the body during the floating. They also work
for braking during stopping.
The reactive swimming systems of the
octopus and the cuttlefish actually function according to a principle
that resembles jet planes. Through a closer examination, it is obvious
that their muscular systems have been designed in the way most suited
to them. It is, of course, absurd to assert that such complex structures
could have been formed through coincidences.
There is an equally
flawless design in the reproductive systems of cuttlefish. The eggs
of these fish have sticky surfaces that enable them to adhere to
cavities in the deeps of the sea. The embryo consumes the nutrients
provided inside the egg until it is ready to hatch. The embryo breaks
the egg casing with a small brushlike patch on its tail. This feature
disappears shortly after hatching.39 Every little
detail has been designed and functions as it is designed to do.
All of this miraculous creation is nothing but an expression of
the infinite knowledge of God.