Name: Foetus Development
Uploaded: 2019-07-19
Duration: 9 min 51 s
Description: A baby goes through several stages of development, beginning as a fertilised egg. The egg develops into a blastocyst, an embryo, and then a foetus.

Question

Give the salient features and five examples of class Aves.

Accepted Answer

Aves is the class of tetrapods that belong to the subphylum Vertebrata. These animals include all the birds. Examples: Corvus (Crow), Psittacula (Parrot), Pavo cristatus (Peacock), Neophron (Vulture), Columba livia (Pigeon), Apteryx (Kiwi), Spheniscidae (Penguin).

Characteristics of Class Aves are given below:
1) Birds are homeothermic or warm-blooded animals with an exoskeleton made of feathers.

2) Body has four divisions i.e. head, neck, trunk, and tail.

3) Paired limbs are present, forelimbs are usually modified into wings that help them in flying; hindlimbs are usually adapted for perching, walking, and swimming.

4) Their feet possess four toes that are covered with scales or feathers.

5) Sweat glands are absent in the skin while oil glands are present, preen gland (oil) is usually found at the base of tail.

6) Fully ossified skeleton with air cavities. Air cavities are present in the bones thus are called pneumatic bones. These reduce body weight and help in the aerial mode of life.

7) Skull bones fused with one occipital condyle. Pinna of ear rudimentary.

8) Teeth are absent altogether; Each jaw is covered with a keratinised sheath, forming a beak.

9) Ribs with strengthening, uncinate processes.

10) The posterior caudal vertebrae are reduced and get fused to form a pygostyle.

11) Air sacs are present in continuation to the lungs that facilitate easy respiration.

12) Crop and gizzard are found in their digestive tract.

Give the salient features and five examples of class Aves.

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