Class Aves: Aves are a class of endothermic vertebrates, commonly known as birds. These animals fall under the phylum Chordata carrying specific features such as toothless jaws with beak, laying of eggs with a hard shell, etc.
Characteristics of Class Aves
- Birds are warm-blooded animals.
- Their forelimbs are modified into wings.
- They have well-developed flight muscles that help during the flight.
- Their hind limbs are adapted for walking, hopping, perching, grasping, wading and swimming.
- There are epidermal scales on their legs.
- The endoskeleton is bony with long hollow bones filled with air cavities. known as pneumatic bones.
- Their spindle-shaped body minimizes resistance of the wind.
- The feathers help in preventing heat loss and reduce air friction by providing passage to the air.
- There is no skin gland except the oil gland.
- The lower and upper and jaws are modified into a beak.
- They have no teeth.
- They have sharp eyesight.
- The alimentary canal has a crop and a gizzard. The crops help in softening food, and the gizzard helps in crushing the food.
- Pigeons and other seed-eating birds lack a gall bladder.
- They have spongy and elastic lungs for respiration.
- The special vocal organ called syrinx is present at the base of trachea.
- Their heart is four-chambered.
- RBCs are oval, nucleated and biconvex.
- 12 pairs of cranial nerves are present.
- They have a single ovary and oviduct on the left side
- All the birds are oviparous and exhibit sexual dimorphism. The eggs have four embryonic membranes- amnion, chorion, allantois, and yolk sac.
Classification of Class Aves
The class Aves is divided into two categories:
This class of birds are extinct. They had a toothed beak with a long lizard-like tail.
These include extant as well as extinct birds. They have no teeth and a short tail.
Eg., Penguin, Grey Heron, Kingfisher, Duck, etc.
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