The general characteristic of Aves are :
1. The body of aves is covered by feather and they are adapted to
for aerial mode of life.
2. Body form : Their body is streamed lined and divided
into head, tail ,trunk and neck. Head is small and round , neck is flexible and
monocondylic (can rotate 360 degree) and tail is short and stumpy.
3. Locomotion : Locomotion is aves is served by two pair
of limbs. fore limbs are modified into wings for flying and hind limb to
support the body, for piercing mechanism , swimming and walking purpose.
There are four fingers. 3 fingers are directed forward and one is directed
backward called hallux. Thus it shows bipedal.
4. Respiration : They respire through spongy and inelastic
lungs. It consists of many air sac.
5. Nervous System : Their consists of 12 pair of cranial
nerve.
6. To reduce their
body weight their bone is hallow , pneumatic
, porous without bone marrow.
7. Skin : Their skin is dry and without gland.
However oil gland or peer gland is which is present at the root of tail secrete
oil to soften and greasy the feathers.
8. Excretion : They perform excretion by metanephric
kidney. Urinary bladder is absent. They are ureotelic(those who excrete uric
acid) .
9. Reproduction System : Sexes are separate in them. Sexual
dimorphism is usually distinct. Male have paired testes. Female have only one
ovary.
10. Fertilization is internal preceded by courtship
(attracting female) and copulation and they are oviparous (egg laying) and
development is direct.
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