Wednesday, April 8, 2009



The skeletons of birds are designed to effectively enable them to fly, walk and even swim in the fastest and most efficient way.

All flying birds are equipped with an extremely strong breastbone (sternum)which has a large flattened plate, called a keel, for the attachment of flight muscles. The muscles wrapping this bone facilitate flight.

The part of the skeleton called the breast plate constitutes a very sturdy support for the wing bones, and is comprised of the breast bone and wishbone that is unique to birds. The bones that carry the wings are very long and fused together. The wing tip feathers attach to the fused "hand" bones. The pelvic girdle extends both downward and backward in order to enable the leg muscles to work more effectively.

The breast bones of birds are relatively inflexible for protection of the body when the wings are closed. That is, the volume of the rib cage does not change during flight, inhalation or exhalation.

Since birds are designed for the purpose of flight, their bones are hollow and wrapped with muscles, which provide miraculous lightness without compromising strength.

The wings are pulled downward by the contracting muscles. When the wings are raised and the small breast muscles (supracoracoideus) are contracted, the large breast muscles (pectoralis major) are flexed. When the large breast muscles are contracted and the small breast muscles are flexed, the wings are lowered.

"Running birds", such as the ostrich, have long legs and strong muscles that function in running, whereas predator birds have shortened bodies and relatively spinal cord sloped, which enables them to move more swiftly.

Sparrows have keeled sternum that enables them to fly for extended periods. This bone is covered with breast muscles.

Praise be to Allah, to Whom everything in the heavens and everything in the earth belongs. Praise will be His in the Hereafter. He is the Wise, the Informed. He knows what penetrates the earth and what issues from it, and what falls down from the sky and what soars up into it. He is the Most Merciful, the Ever-Forgiving." (Surah Saba': 1-2)

A night owl, with a wingspan of 21.7 inches (55 centimetres), is an ideal night hunter. Its large eyes are lodged in the front its head. This location is very advantageous in its finding its prey. Another property of its eyes is the capability for night vision.

In addition, owls can rotate their heads three-quarters of the way around, which further adds to the size of their visual field. The ears of this bird are also very sensitive. It can hear from its place on the branch of a tree the quite noises that a rat makes in the bushes. It can flap its wings virtually without a sound. The owl latches on to trees or to its prey with large and powerful claws. One easily sees that this creature is created as the ideal night predator.

Humankind made a tremendous leap in flight technology in the 20th century. One of the key ingredients in this advance was the study by scientists of the designs found of the bodies of birds. In the design of aircraft, many aerodynamic principles found in birds are implemented, leading to very successful applications. This is due to the flawless creation of birds, just as in the perfection evident in the rest of the creation.


The miraculous creation of birds does not end with wings, feathers or their migration skills. Another extraordinary design feature of these creatures is in their eggs.

However ordinary it may seem to us, the egg of a chicken has about fifteen thousand pores resembling dimples on a golf ball. The spongy structure of smaller eggs can only be observed under the microscope. These spongy structures give eggs added flexibility and increase their resistance to impact.

An egg is a miracle of packaging. It supplies all the nutrients and water that the developing foetus needs. The yolk of the egg stores protein, fats, vitamins and minerals, and the white works as a reservoir of fluid.

The developing chick needs to inhale oxygen and exhale carbon dioxide. It also requires a source of heat, calcium for its bone development, protection of its fluids, protection against bacteria and physical impact. The eggshell provides all of these for the chick, which breathes through a membranous sac that develops in the embryo. Blood vessels in this sac bring oxygen to the embryo and take carbon dioxide away.

Eggshells are amazingly thin and sturdy, and so transmit the body heat of the brooding parent.

Chicks have a special "egg tooth" that they use only to hatch the egg. This tooth is formed just before hatching and, amazingly, disappears after hatching.

The eggshell is strong enough to protect the embryo during twenty days of incubation. However, it is also easily breakable so that the chick can emerge.

A Necessary Loss

During incubation, the egg loses 16% of its water content in the form of evaporation. Scientists long believed this to be harmful and due to the porous structure of the eggshell. However, the most recent research shows this loss to be necessary for the chick to emerge from the egg. The chick needs oxygen and space to be able to move its head just enough to crack the shell while hatching. The evaporation of water creates the room and oxygen required.

Furthermore, water loss ratio is adjusted to vary between 15 to 20% for ideal conditions depending on the type of eggshell. For instance, water loss in the eggs of loons is a few times higher than in others that incubate under dryer conditions.

The Design of an Egg for Durability

The durability of an eggshell is as crucial as its functioning in terms of air, water and heat. It has to withstand external impact as well as the weight of the incubating parent.

A closer examination reveals that eggs are designed for sufficient durability. Allah created smaller and larger eggs different from one another. Eggs of larger birds are usually harder and less flexible whereas eggs of smaller birds are softer and more elastic.

Chicken eggs are rigid and rough, but they do not break when falling over one another. The rigid shell also protects them from attack. If smaller eggs were to be as rigid and rough as the chicken egg, they would have broken much easier. Studies show smaller eggs are not rigid, but sturdy and flexible, which prevents them from breaking under impact.

The flexibility in the structure of an egg not only serves to protect the chick but also determines the way that the chick hatches it. A chick that will come out of a rigid and rough shell only needs to open a couple of holes at the blunt end of the egg before pushing its head and legs out. The chick meets the world by lifting the hat-shaped end cover that is formed by the cracks connecting these holes. 25

The figure shows phases of development of a chicken egg in the ovary. It takes about fifteen to sixteen hours for a chicken egg to form after fertilisation.

Eggshells are created in such a way as to supply oxygen to the chick inside through the porous holes. The figure above illustrates the passage of carbon dioxide, water and oxygen through the pores.

(left) The figure above shows the shell of the loon egg laid on wet and muddy ground. The shell is covered with a layer called the "inorganic spheres layer", which prevents the pores from closing and the chick from suffocating.

(right) The eggs of birds living under different conditions vary as well. The figure above shows the section of an eggshell of the egg of a rainbird. The specially crystallised outer layer protects the egg, where it is laid in a gravel bed, against impact and scratches.

Eggs of many birds are created with camouflage colours. Loon eggs resemble the form of a pear, which is the ideal shape for sharp rock formations. When they receive an impact, they do not fall easily but roll around in circles.