The word ‘animal’ is derived from the Latin wordanimaliswhich
means ‘having breath’. The Kingdom Animalia is characterized by
eukaryotic and heterotrophic organisms. They are multicellular and lack
cell wall. They depend directly or indirectly of plants for their food.
Food is ingested and digested in their internal cavity and food reserves
are stored as glycogen or fat. Nutrition is holozoic, i.e., by
ingestion of food. Animals follow a definite growth pattern, the adults
have a definite shape and size. Higher forms of animals exhibitwell
developed sensory and neuromotor mechanism. Most of the organisms are
capable of locomotion. Reproduction is by copulation of male and female
which is followed bydevelopment in embryonic stages.