What is the Hierarchy of the Classification Groups
In classification, the organisms that closely resemble one another are placed in a group. These groups are further placed in larger groups on the basis of close similarities. The larger groups are again placed in still larger groups. The various grouping levels or ranks in classification are known as categories. Each category has its specific name. There are seven major categories.
- Phylum (for animals)/division (for plants)
1. Species :
Species is the lowest category regarded as basic unit of classification. It is a group of similar individuals which resemble with each other in morphology, breed among themselves but not with others and probably descended from a common ancestor.
2. Genus :
A genus is a group of closely resembling spcies having a common ancestry. All the species in a genus show similarities in broad features of their organization but differ in minor details.
3. Family :
A family represents a larger group of closely related genera. It is composed of one or more genera. For example, the genus Felis of cats and the genus Panthera of lion, tiger and leopard are placed in the family Felidae because all these animals have retractile claws.
4. Order :
An order is a group of closely related families. For example, the family Felidae (that includes cats) and the family canidae (that includes dogs) are assigned to the order carnivore because both cats and dogs have large canine teeth and are fleash eaters.
5. Class : A class is a group of related order.
6. Phylum/Division :
Phylum (in case of animals) or Division (in case of plants) is a group of related classes.
7. Kingdom :
Kingdom is the highest category in biological classification. It is a group in Phyla (in case of animals) or divisions (in case of plants).
The various categories used in biological classification can be arranged in a hierarchy (i.e.; ranked one above the other). It was introduced by Linnaeus and is, therefore, called Linnaenan hierarchy. The hierarchy indiciates the various levels of Kinship (i.e., relationship by blood). Nearer the categories in hierarchy the greater is the similarity between their organisms. The hierarchy of major categories is given below –