a. Amphibia – Dual habitat

Explanation: The word amphibia itself means two lives. The amphibians live on land as well as in water.

b. Mammals – Mammary glands

Explanation: The mammals have mammary glands to release milk to nourish their young ones.

c. Chondrichthyes – Cartilagenous notochord

Explanation: Chondrichthyes have cartilaginous notochord at a young stage but it is replaced by cartilage later.

d. Osteichthyes – Air bladder

Explanation: Osteichthyes have a sac which contains air. This sac is called Air bladder.

e. Cyclostomata – Sucking and circular mouth without jaws

Explanation: Cyclostomes have sucking and circular mouth without jaws which is surrounded by tentacles and the tongue bears teeth

f. Aves – Pneumatic bones

Explanation: Aves have bones which are hollow and filled with air. Such bones are called pneumatic bones. This makes them light weight.