Q41 of 525 Page 259

Write down four characters of Chondrichthyes. Give two examples.

Characters of Chondrichthyes:

(i) They are marine animals.

(ii) They have cartilaginous endoskeleton.

(iii) The skin is tough, containing minute placoid scales.

(iv) No air bladder is present.

Examples- Scoliodon (Dog fish) and Trygon (Sting ray).

Name the phylum in which ambulacral system is present. What is its function?

What are adaptations in fishes due to which they are aquatic?

Write down four characters of Osteichthyes and give two examples.

What are differences between the following :

(a) Cartilaginous fishes and bony fishes;

(b) Amphibia and Reptilia ;