Animal Diversity, Classification & Binomial Nomenclature PDF

ANIMAL DIVERSITY, CLASSIFICATION AND THE BINOMIAL NOMENCLATURE ANIMAL DIVERSITY  There are about 1.8 million described species of plants and animals out of which animals account for about 1.4 million species.  It has also been estimated that there could be as many as tens of millions of ani...

ANIMAL DIVERSITY, CLASSIFICATION AND THE BINOMIAL NOMENCLATURE ANIMAL DIVERSITY  There are about 1.8 million described species of plants and animals out of which animals account for about 1.4 million species.  It has also been estimated that there could be as many as tens of millions of animal species that are not yet identified or described, especially in the environments that are difficult to explore, e.g. ocean floor.  The diversity of animals necessitates the need for zoologists to specialise in different areas, as it is practically impossible for a zoologist to be a specialist in over one million species of animals. Animal diversity necessitates the need to create different areas of specialization in Zoology and create an avenue for a better understanding of the various taxa. Hence, the following sub-disciplines of Zoology (based on taxonomy): Protozoology: the study of protozoa Entomology: the study of insects Malacology: the study of molluscs (e.g. snails, octopus) Carcinology: the study of crustaceans (e.g. crabs, shrimps) Ichthyology: the study of fishes Herpetology: the study of amphibians (e.g. toads, frogs, salamanders, snakes, crocodiles) Ornithology: the study of birds Mammalogy: the study of mammals ANIMAL CLASSIFICATION  The branch or sub-discipline of zoology that studies the classification of, and the evolutionary interrelationships among animal groups is called SYSTEMATICS.  Any grouping of animals (organisms) that shares a particular set of characteristics forms an assemblage known as TAXON (Plural: TAXA).  Hence, the scientific classification of animals is known as TAXONOMY while the study of evolutionary groups among species is known as SYSTEMATICS. Modern taxonomists use the following taxa which are listed in hierarchical order, starting from the largest taxonomic unit (using human as a case study): Domain: Eukarya Kingdom: Animalia Phylum: Chordata Class: Mammalia Order: Primates Family: Hominidae Genus: Homo Species: sapiens NOTE: In the classification of an animal, the trend is as listed above, i.e. Domain, followed by Kingdom, Phylum, Class, Order, Family, Genus, Species BINOMIAL SYSTEM OF CLASSIFICATION  All animals are classified into hierarchies based on their relatedness.  The modern and universal system of animal classification is known as the Binomial Nomenclature.  The binomial nomenclature was primarily developed for plants by a Swedish Biologist known as Karl von Linne (Carrolus Linnaeus) (1707-1778).  This binomial nomenclature system has since been adopted for animals.  Using the binomial nomenclature, each kind of organism (animal) is allotted a two-part name.  The first part indicates the genus while the second part indicates the species to which the animal belongs.  Both (genus and species) names (also known as zoological names) must either be italicized or underlined (if it is handwritten). EXAMPLES  The genus name for Lion is ‘Panthera’, while the species name is ‘leo’  Hence, Panthera leo (italicised if it is typed as the case is here) OR  Panthera leo (underlined if it is hand-written)  NOTE: The International Code of Zoological Nomenclature (ICZN) stipulates that no two kinds of animals have the same binomial name, and every animal has only one correct binomial name.  WHY USE BINOMIAL NAMES AND NOT COMMON NAMES? 1. All animals have their common names which could vary from one locality or language to another. For instance, a bird called ‘owl’ (common name) in English is called ‘owiwi’ in Yoruba. The same bird is called different names in other languages. This implies that a single species of animal could have hundreds of different common names. 2. A binomial name brings order to a chaotic world of common names. Once a species is allotted a binomial name, it goes by the name among scientists in all regions and languages of the world. 3. Some common names refer to a higher taxonomic category and do not specify a particular species in the taxon. For instance, dragonflies, crustaceans, catfishes are all common names for higher taxonomic categories. They do not specify the particular species in each case. Hence, the need for a binomial name.