Flight-Adaptation-in-Birds.ppt

Flight adoptation in birds

1. FLIGHT ADAPTATIONS
IN BIRDS
Dr.JagdishKaur
P.G.G.C.,Sector11
Chandigarh

2. FLIGHT ADAPTATION IN BIRDS
onlyvertebratesspecializedtoaerialmodeoflife.
Thesuperorderratitaeorpalaeognatheaeincludesthe
flightlessterrestrialbirdse.g.Ostrich,Kiwietc.
Superorderimpennaeorspenisciformesincludesmarine
andflightlessbirdsandoccurinantarcticregione.g.Penguin.
Thesuperorderneognatheaeincludestheflyingormodern
birds.
Flyingbirdsareheavierthanairmachinesandshowa
numberofmorphological,anatomical&physiological
modificationstosuittheiraerialmodeoflife.
Thesearecalledvolantadaptation.

4. MORPHOLOGICAL ADAPTATIONS
1.Body Shape
Generallyspindleshapedorstreamlined
Lacktheextralateralprojectiontominimizetheresistanceinair
duringflight.
2.Feathery Exoskeleton
Feathersarespecialintegumentaryderivativesandareoneofthe
diagnosticfeaturesofbirds,andperformfollowingfunctions:
Contourfeathersmakethebodystreamlined.
Formaninsulatingcoattopreventthelossofbodyheat.
Wingquillfeather,calledremigesprovidealargeandbroad
surfaceareafortheairmovement.

6. 3.FlightOrgans
Theforelimbsaremodifiedintopowerfulflightorgans,called
wings.
4.MOBILE NECK & BEAK
Transformationofforelimbsintowingsisdullycompensatedby
thedevelopmentofextrememobilityofthelongandflexibleneck
forreachingfood.
•Themouthisboundedbyahornybeakwhichhelpiningestion,
nestbuildingetc.

8. 5.EQUILIBRIUM
•Shifting of light organs towards upper part of body &
heavy organ towards lower.
•That shifts the centre of gravity to the posterior part of
body
This low centre of gravity prevent the turning of the
body of a bird in the air.
6.STEERING APPARATUS
Shorttailbearingatuffoflongtailquill
feather(retrices),thatassistinsteering,
liftingandcounterbalancingduringflying.

9. ANATOMICAL ADAPTATIONS
1.FLIGHT MUSCLES
Muscles of back are greatly reduced but the flight muscles are
greatly developed and highly vascular.
These have long and straitedmuscle fibsesso that they do not
undergo fatigue even after prolonged activity.
2. LIGHTNESS AND RIGIDITY OF ENDOSKELETON
light and rigid endoskeleton
Their endoskeleton is built on hollow girder principle.
Rigidity is required to resist the pressure of air current during
flight.
Lightness achieved through following adaptation:
Skull bones are thin and papery.
Pneumacity:most of long bones are filled with air spaces to make
them light such bones are called Pneumatic bones, which also
decreases the specific gravity of the bird.

10. In pigeon there are three types of flight muscle.
Pectoralisdepressor major :-These are largest size flight
muscle. Their contraction cause powerful downstrokeof
wings, arise from the ventral side of sternalkeel.
Pectoraliselevator muscle :-these arise from anterior part of
the sternum . Their contraction cause upstroke of the wings.
Accessory muscles :-these supplement the pectoralismuscles
to elevate or depress the wings. These are:-
1. coraco–brachialislongusor coraco–brachialisbrevis.
2. Biceps and triceps
3. Extensor carpiradialisand extensor carpiulnaris.

12. •Presence of Air Sacs
•In birds there is tendency towards reduction in
the number of bones.
•Lightness is also achieved by the loss of certain
organs
e.g. teeth, gall bladder, urinary bladder and
right ovary
and oviduct in the female.
3.RIGIDITY IS ACHIEVED THROUGH FOLLOWING ADAPTATIONS:
Complete fusion of skull bones so that even the
sutures are absent or indistinct between them.
Caudal vertebrae are fused to form a small and
triangular pygostyleto provide stability in the air.

13. PHYSIOLOGICAL ADAPTATION
Digestive system: Birds have following adaptation in their
digestive system:
Beaks are variously modified to intake large amount of
food in the mininumperiod.
A masticatorygizzard with a thick cuticularlining is
developed to compensate the absence of teeth.
Rate of digestion is very high due to immediate
utilizations of digestive juices due to presence of two
bile ducts and three pencreaticducts.

14. 2.Respiratory system:
In birds, the rate of respiration is very high.
It is about 25-29 times per minute.
To compensate small sized and inelastic
lungs, the birds show double respiration in
which the lung alveoli receive fresh air
during both inspiration and expiration.
Air sacs are thin and distensible sacs
associated with the lungs.

15. CIRCULATORY SYSTEM
Avian heart is larger in size, more powerful and
more efficient.
Their heart is four chambered with double
circulation.
Rate of heart beat is faster in birds which
increase cardiac output and blood supply to
various organs of body.
RBCS of birds have large amount of
haemoglobin.
Homeothermy: birds are warm blooded or
homeothermal vertebrates.

16. 5.EXCRETORY SYSTEM:
Loop of henle is long sized.
Urinary bladder is absent so that nitrogenous
wastes are immediately expelled out of the
body.
Brain and sense organs: Birds have to depend
more on the sense of sight to locate their food so
that optic lobe of midbrain and eyes are well
developed.
Brain is large sized and well developed to co-
ordinate the complex movements of wings and
the feathers during flight.

17. Theseadaptationrevealsthat
flightinbirdsisatechnicalwonder
whichenablesthemtoexplorenew
habitatsforfoodandshelterandto
escapefromtheunfavourable
climaticconditionandenemies.