Taxonomical Hierarchy

In this topic, we are going to discuss taxonomic category and taxonomical hierarchy used to classify organisms.

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Taxonomic Category

Categorization of organisms to groups which have similar characteristics is called as taxonomic categorization. By grouping organisms into categories, it becomes easy for us to identify other characteristics of the organism. Some of the categories which we already know are birds, mammals, fish, etc.

Taxonomic Hierarchy

Taxonomic Hierarchy is the arrangement of categories by providing the rank to each category. The taxonomic category which has the lowest rank is placed at the bottom of the hierarchy and the one with the highest rank is placed at the top of the hierarchy.

After studying taxonomies of all known organisms, common categories such as Kingdom, Phylum(for animals) or Division (for plants), Class, Order, Family, Genus, and Species are identified for classification. Species has the lowest rank and kingdom has the highest rank in the hierarchy.

Species:

Group of organisms with fundamental similarities among them are grouped under species. Based on the morphological( shape or structure) characteristics and capability of breeding and produce fertile breeding. Donkey and Horses belong to the same kingdom, phylum, class, order, family as well as the genus but they are from different species. Therefore, if a donkey and the horse happen to breed, they produce an offspring called a mule. The mule is infertile, meaning that it cannot reproduce offspring because it is a product of organisms of different species. Species is further subdivided by subspecies, varieties, and races. These taxonomic categories are seldom used as compared to species.

Example :

• Panthera leo is the scientific name for Lion. Panthera represents the genus and contains species Tigris.
• Solanum tuberosum is the scientific name for Potato. Solanum represents genus and Solanum includes species like nigrum and melongena.
• Homo sapiens is the scientific name for the human being. Homo represents genus and sapiens represent the species(modern humans). Humans belong to Hominidae Family(apes, humans), Primate Order(mammals with hand and feet), Mammalian Class(animals with backbone and hair), Chordata Phylum(animals with backbones), Animalia Kingdom.

Genus:

Genus comprises a group of closely related species that had more common characteristics compared to another genus. Some genera have only one species, such genus is called as Monotypic and genera with more than one are called as polytypic.

Example:

• Brinjal and Potato are different species but belong to the same genus Solanum.
• Pardus(leopard and Tigris(tiger) are two different species but belong to the same genus Panthera, whereas Felis is another genus which includes the cat.

Family:

Family has a group of closely related genera. Families are mainly characterized based on the vegetative and reproductive features of plants and animals.

Example:

• Three generas namely Solanum, Petunia, and Datura are placed in the family Solanaceae
• Genus Panthera(consists of species lion, tiger, leopard) and Genus Felis(consists of cats) are placed under the family Felidae. Though there are similarities between cats and dogs, dogs belong to another family named Canidae which consists of dogs and wolf.

Order:

Group of families which exhibit similar characteristics.

Example:

• The solonace family is included under Convolvulaceae Order.
• Felidae and Canidae families are included under Carnivora Order.

Class:

Group of closely related orders belongs to the same class.

Example:  Order Primata comprising of monkey, gorilla, and gibbon is placed in class Mammalia which also includes another Order Carnivora comprising of animals like tiger, cat, dog.

Phylum or Division:

Group of related classes is called Phylum or Division. For animals, it is called Phylum and for plants, it is called as Division. In case of animals, Phylum Chordata includes animals that have the notochord and dorsal hollow neural system.

Kingdom:

Group of closely related Phylum or Division is called as Kingdom. This is the highest category for organisms. All animals are classified as Kingdom, Animalia. The kingdom Plantae comprises of plants from various divisions. This level of grouping of the organism is based on observable characteristics of an organism.

Hierarchical Taxonomy of Organisms

Based on the ranking of classification, the hierarchy is given below.

Human beings belong to the homo sapiens species which belongs to Genus (Homo) that belongs to Family (Hominidae) that belongs to Order (Primata) that belongs to the class (Mammalia) that belongs to Phylum (Chordata) that belongs to Kingdom(Animalia).  From this example, we can observe that the number of common characteristics comes down when we move up the classification. Organisms in same Kingdom share fewer characteristics when compared to organisms belonging to same species.

TODO: Draw Diagrams for below hierarchy.

Housefly (Musca domestica) belongs to genus(Musca) that belongs to the family(Muscidae) that belongs to the Order(Diptera) that belong to the Class(Insecta) that belongs to the Phylum(Arthropoda) that belongs to Kingdom(Animalia).

Mango (Mangifera indica) belongs to genus(Mangifera) that belongs to the family(Anacardiaceae) that belongs to the Order(Sapindales) that belong to the Class(Dicotyledonae) that belongs to the Division(Angiospermae) that belongs to Kingdom(Plantae).

Wheat (Triticum aestivum) belongs to genus(Triticum) that belongs to the family(Poaceae) that belongs to the Order(Poales) that belong to the Class(Monocotyledonae) that belongs to the Division(Angiospermae) that belongs to Kingdom(Plantae).

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Concepts in taxonomical hierarchy chapter

Species

Genus

Family

Order

Class

Phylum

Kingdom

Mnemonics under this chapter

Order of Taxonomic Hierarchies

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