Explain how Evolution and classification are …

Organisms differ in their form, structure and mode of living. Hence, based on their similarities they should be grouped. The grouping of related organisms helps us in studying their evolutionary relationships. Classification is the division of organisms on the basis of characteristics into groups and sub-groups. A characteristic may be a particular form or function.
For example, classification of animals can be done based on some criteria.
Criteria for classification: Animals are classified on the basis of different features.
*Cellular or tissue level of body organisation.
*Body symmetry.
*Type of body cavity called as coelom.
*Presence or absence of segmentation.
*Presence or absence of a backbone.
Evolution: It is the sequence of gradual changes over millions of years in which new species are produced. Classification of species is done by knowing the characteristics which evolved over a long period of time.