The animals were divided into groups based on a few characteristics. These characteristics help to classify animals into groups and phyla.
Animals with a backbone having vertebral columns are vertebrates and are classified into different classes like birds, fishes, amphibians, reptiles, and mammals.
The group of animals bearing hairy skin in mammals as these hairs play an important role in thermoregulation.
Animals with three pairs of legs were grouped into the phylum Arthropoda. This is the largest phylum consisting of around 80% of the total known species. Examples: insects.
Animals with feathers were classified in class Aves. These provide shape to the birds and provide a streamlined body for flying.
Final Answer:
(a) Animals with a backbone -Subphylum Vertebrates In phylum Chordata
(b) Animals with a hairy skin – class mammals
(c) Animals with three pairs of legs – phylum Arthropoda
(d) Animals with feathers – class Aves