1 body of a bony fish does not show gills as they are covered by

a)scales b)fin c) skin d) operculum

2 how many wings does a cockroach have???

3 what is function of cnidoblast cells in hydra

4 give 3 difference between body and catilagenous fishes

1.scales

2. coackroach has 2 wings.I think so. 

3. cnidoblast help in capture of  food. they are also known as stinging cells.

4.cartilageneous are made of cartilage. they are mostly marine forms. it's mouth is ventrally located. they excrete products like ammonia.

Bony fishes have hard skeleton . they are fresh water forms. it's mouth is terminally located.they excrete urea.