Question

Some animals breath through lungs and skin .My question is why only some animals why not all can breath through both with lungs and skin ?

Answer 1

some amphibians breathe both through their skin as they live both on land and water, when they live on land they breath through lungs but when they live in water they breathe through skin. Animals which are terrestrial and are developed breathe through lungs as they do not have to live in water and hence the role of skin is reduced.