(i) Pisces : Exoskeleton of scales, endoskeleton of bone cartilage, breathing through gills.
(it) Amphibia : Gills in larval stage, lungs in most adults, slimy skin.
(Hi) Reptilia: Exoskeleton of scales, laying eggs outside water.
(iv) Aves : Exoskeleton of feathers, fore limbs are modified as wings.
(u) Mammalia : Exoskeleton of hair, external ears, mostly giving birth to young ones.