Question

What are differences between the following :

(a) Cartilaginous fishes and bony fishes ;

(b) Amphibia and Reptilia ;

(c) Aves and mammals.

Answer 1

(a)

Cartilaginous fish	Bony fish
They have a cartilaginous endoskeleton.	They have a bony endoskeleton.
They contain 5-7 pairs of gill slits and operculum is absent in them.	They contain 5-7 pairs of gill slits which are covered with an operculum.

(b)

Amphibia	Reptilia
They have a glandular, smooth and moist skin.	They have a non-glandular, dry and keratinised skin.
Fertilisation is external.	Fertilisation is internal.

(c)

Aves	Mammals
The body is covered with feathers and scales.	They lack feathers and scales; however, they have hair on their body.
They have a toothless beak and hollow and pneumatic bones.	They do not have beaks; teeth are present and the bones do not possess air cavities.