What are the modifications that are observed in birds that help them fly?
Solution
Birds have adapted to aerial mode of life through the following modifications:
(1) Body is streamlined and spindle shaped which minimise resistance to the wind.
(2)Body is covered with feathers. It reduces the friction, prevent loss of heat and help to maintain constant temperature.
(3)Forelimbs are modified into wings, which help during flight.
(4)Flight muscles are greatly developed
(5) Most of the bones are pneumatic, hollow and filled vvith air which makes the body lighter and helps in flight
(6)Birds are warm-blooded. They maintain a high body temperature (40° – 46°C). This is necessary for flight.
(7)Heart is four-chambered and functions efficiently with double circulation.
(8)Air sacs are present which act as reservoir of air and helps in temperature regulation
(9)Urinary bladder is absent (except in Rhea) and only one ovary is present which reduces the weight, which is essential for flight.
