Mechanism of flight in bird

Slide by Rajani kumari

1. MECHANISM OF FLIGHT IN BIRD

2. Feeding (feeding to there young ones) Breeding. Avoiding Predators. Migration. BIRD FLY DUE TO 4 REASONS

3. MECHANISM OF FLIGHT IN BIRD Mechanism of flight is based on two main point- Sir George C ayley Bernoulli’s principle Aerodynamics Properties

4. BERNOULLI’S PRINCIPAL This principle was first worked out by Swiss mathematician DANIEL BERNOULLI in 1738.

5. BERNOULLI’S PRINCIPAL Bernoulli’s principle can be defined mathematically i.e. V ∞ 1/P [where, V= velocity, P=Pressure. V elocity is inversely proportional to pressure. When the pressure is least where velocity is greatest and vice versa. Bernoulli’s principle apply for the adult fluid flow. But in case of bird there is no fluid flow but there is air that interact with wing. Wing act as a solid and the air act as a fluid flow.

6. BERNOULLI’S PRINCIPAL When the air flow just comes towards the bird the air bifurcate in two ways- Over the wing & Below the wing. There is a displacement of air towards the wing that cause the lifting of the bird.

7. BERNOULLI’S PRINCIPAL It is says that the upper surface of the wing is convex and the lower surface of the wing is concave. The concave side of the wing has the lower surface area, so there will be less displacement. Whereas, the convex side of the wing has more surface area, so there will be more displacement i.e., there will be less pressure and more velocity and vice versa.

8. BERNOULLI’S PRINCIPAL Due to this pressure difference above or beneath the wing- It lift the wing up. The drag force is less there.

9. BERNOULLI’S PRINCIPAL There is a forward movement of the bird. lifting of the bird. This all causes the bird to fly.

10. AERODYNAMICS PROPERTY The Aerodynamics property was first discovered by SIR GEORGE CAYLEY IN 1809. He called both as “THE FATHER OF AEROPLANE” and also “THE FATHER OF AERODYNAMICS”. He was born in 27 th Dec 1773. Sir George C ayley

11. AERODYNAMICS PROPERTY Aerodynamics is a branch of science which deals with the interaction of air with solid object and how air moves around this solid object. The air exhibit different types of force on the wing and this force can be resolved into- Vertical lift component perpendicular to the air. Backward drag component parallel to the air sting. We see the force due to gravitation that universally denoted by Fmg. Lift force denote by = F L   Thrust force denoted by = F T Drag force denoted by = F D   Gravitational force = F G  

12. AERODYNAMICS PROPERTY Condition for the bird to fly :- F L   ≥ F G   First Condition . Force of the lift must be greater or equal to gravitational force. F T > F D 2 nd Condition. Force of thrust must be greater than drag force otherwise bird cannot fly.

13. AERODYNAMICS PROPERTY More + More + Less - Less - The lift and thrust force that are the two +ve force due to which the bird fly and weight and drag are two –ve force due to which the bird cannot fly because they resist the flight of the bird.

14. FLIGHT ADAPTATIONS FOR AERIAL LIFE Modification of body in flight for aerial life – Morphological modification -

15. Body contour – Spindle shaped of fusiform body to ensure least wind resistance. Low center of gravity. Presence of feathers – Feathers, very light, hardly adds weight to the bird. Feathers also serves as a blanket enveloping air around the body and adds buoyancy. Forelimbs are modified into wings – Forelimbs becomes modified into unique and powerful propelling organs, i.e., wings covering with feathers. MORPHOLOGICAL MODIFICATION

16. Mobile neck and beaks – Mobile neck and beak help them for feeding, nest- building, preening , etc. Bipedal locomotion – Hind limbs supports the body weight and acts as locomotory organs in the ground. Perching – Strongly developed muscles so modified that when a bird sits in a perch, the toes automatically grips the perch. MORPHOLOGICAL MODIFICATION

17. MORPHOLOGICAL MODIFICATION Perching muscles are of two types – Flexor Muscles & Extensor Muscles. Flexor muscles – There occurs 8 flexor muscles on the back of the tibio-tarsus bone of hind limb. Extensor muscles – These muscles are in front of the tibio-tarsus. The toes are unlocked by extensor muscles. PERCHING MUSCLES

18. Important flexor muscles are – Ambiens Peroneus medium Gastrocnemius Flexor perforans (above the knee). Important extensor muscles is – Dermal muscles. PERCHING MUSCLES

19. Short tail and tail feather- Short tail with feathers help in lifting, and counterbalancing. MORPHOLOGICAL MODIFICATION

20. ENDOSKELETON- Endoskeleton are light and provides large surface for attachment of muscles. Bones are pneumatic (hollow). Teeth absent. Synsacrum present . T-Shaped sternum The fusion of distal tarsal with metatarsals to make the body light. ANATOMICAL MODIFICATION

21. MUSCLES OF FLIGHT Muscles on the back are much reduced and flight muscles on the breast are strongly developed. There are three types of flight muscles are as follows- Pectoral muscles. Accessory muscles & Tensor muscles.

22. They are of two Types- Pectoralis Major Muscles- This muscles is very large, triangular and most powerful flight muscles. Weight is 1/5 th of the body, dark red in color. Pectoralis Minor Muscles- this muscles is small and elongated which help in lifting the wing during flight. MUSCLES OF FLIGHT PECTORAL MUSCLES

23. MUSCLES OF FLIGHT ACCESSORY MUSCLES Accessory muscles also help in lifting and dragging the wing during flight. It arises from coracoids. TENSOR MUSCLES Three muscles are together called as tensor i.e.,- Tensor Longus. Tensor brevis. Tensor accessorius. This muscles keep the propatagium fully stretched when the wing is extend in the flight.

24. DIGESTIVE SYSTEM- Rectum reduced in size. Therefore metabolism very fast and waste elimination is very fast. Excretory waste product is uric acid. RESPIRATORY SYSTEM- Some alveoli modified into a large air sac present throughout the body in thorax, abdomen which function as 2 nd supply of oxygen. ANATOMICAL MODIFICATION

25. CIRCULATORY SYSTEM- Birds are warm-blooded animal. Heart is large and had four chambers. Heart functions very efficiently with a double circulation of blood. REPRODUCTIVE SYSTEM- Single ovary and an oviduct is present in female, is a weight reducing device. TEMPERATURE- Body temperature is 40-42°C. ANATOMICAL MODIFICATION

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