Adaptation of aves to flight
Effective flight is possible only when two requirements are met, light weight
of the body and the supply of energy. Hence, the organs that are modified
for effective flight are:
1. Birds have short body with compact bones. This reduces the weight of the body
and makes it light.
2. There are different kinds of feathers present in birds: outline feather helps to
decrease the drag of the body by making it streamlines; primary feathers helps
to provide shape to the wings and make the flight possible; tail feather are used
as rudder for balance of the body.
3. Bones in birds are either hollow or fused to reduce the weight of the body. The
fusion of caudal bone to form pygostyle and hollow bones of skull are good
example of it.
4. Absence of teeth and present of beak is also one of the important*adaptations
for flight in birds.
5. Forelimbs are modified into wings and hence aerodynamics in shape. They are
also close to the centre of gravity.
6. Different muscles present in birds helps in the movement of legs, wings, neck
and tail. Mainly wings are made of strong muscle so as to provide energy for
flying which are called pectoral and breast muscles.
7. Birds generally eat foods that are small and light but which high source of
energy. They have gizzard that helps to grind the eaten food and absorb it.
Beside this, some birds also have crop that aids in softening and absorbing of
eaten food.*
8. The most developed system in birds is the respiratory system. It is highly
developed because of the energy required for flying mechanism. Though the
lungs are relatively small but there is a great interconnection with the inner
organs which generates the required energy. The air that is taken in passes to
the air sacs on the posterior side then reaches the lungs. Similarly, when on
second breathing; the air that is already present in the posterior side rushes to
the anterior side thus leaving the space for next round of breathing, and then the
inhaled air enters the posterior side. This way exchange of gases takes place.
Generally most of the birds have only one way of air current but there are also
some that possess bi- directional air current. Birds lac alveoli, instead many small
sacs called parabronchi are present that are connected to the capillaries.*
9. The circulation of blood uses four chambered heart with two atria and two
ventricular.*
10. Blood with high blood pressure and high amount of sugar is present in the avian
heart.
11. 11. Eyes are well developed having binocular vision in birds whereas the
olfactory organs have reduced function. It is because good sight is necessary for
safe flight.
12. Ovaries and testis are present but the size is reduced, in some only one ovary is
functional.
13. In most of the female birds liver is pushed towards right side in order to balance
the weight of the body
These are some of the modification in different organs of aves for smooth
and effective flight. Most importantly, these are just the basic body plan for
flight adaptation, but there can be variation in the structure, size and types
of some organ according to their adaptation in particular climate or the
regions.
