Transcript Birds - n35zoo

AVES - BIRDS
2 main groups
 Paleognatha – Flightless birds which include
ostriches, emus, rheas, cassowaries
 Neognatha – Flying birds
Adaptations For Flight
1. Body shape -Body long and
spindle shaped (aerodynamic).
Neck long for balance and food
gathering
2. Limbs - Forelimbs usually modified for
flying. (Hindlimbs for perching,
walking, swimming, etc.)
Wing shape:
Called an airfoil
Upper surface of wing is longer than lower
surface. Air travels faster above than
below, so air pressure above wing is
decreased causing the wing to lift.
Lower air pressure
Higher air pressure
3. Body Covering - Body covered with
feathers. (Legs covered with scales.)
4. Skeleton - Bony skeleton with air
cavities hollow for reduced weight.
Sternum with keel. (Jaws cornified to
form beak.)
5. Nervous system Hearing and vision
very keen.
6. Circulation - 4
chambered heart with
double circulation.
7. Temperature control – Endothermic
for a high activity level
8. Respiration - Slightly expansible
lungs and air sacs among organs and
skeleton. (Syrinx (voice box)
near junction of
trachea and bronchi.)
9. Excretory system Semi-solid uric acid
waste. No bladder.
10. Reproduction Sexes separate. In
females only the left
ovary develops (to
reduce weight).
11. Fertilization internal. Amniote egg
with hard shell.