Zoology Notes: 019 Unit 3

Unit 3 Taxonomy, or Systematic Zoology, is the systematic classification of animals. It has two important objectives: classification, the arrangement of the kinds of animals in a hierarchy of groups; and nomenclature, the procedure of assigning names to kinds and groups of animals. It is imperative that a universally recognized system for naming and classifying animals be adopted to ensure methodical storage, retrieval, and communication of zoological information. The flowering of the science of taxonomy in the 18 th century culminated in the works of Carolus Linnaeus (1707-1778), who gave us the modern scheme of classification. Linnaeus was a Swedish botanist at the University of Uppsala. He worked out a fairly extensive system of classification for both plants and animals. His scheme of classification, published in his great work System Naturae, emphasized morphological characteristics as a basis for arranging specimen in collections. Linnaeus’ scheme involved arranging organisms into an ascending series of groups of increasing inclusiveness. Species were grouped into genera, genera into orders, and orders into classes. This taxonomic hierarchy has been considerably expanded since Linnaeus’ time. The major categories or taxa (sing. taxon) now used are as follows (in descending series): Kingdom, Phylum, Class, Order, Family, Genus, and Species. Linnaeus originated the practice of binomial nomenclature, by which each newly described species is given a latinized dual name: generic and specific. The genus is written with a capitalized initial letter. The species is written without the capitalized initial letter. The scientific name is always printed in italics or underlined if this is not possible (i.e. if handwritten or typewritten). For example, the domestic dog is called Canis familiaris. This provides an immediate handle for grouping relatedness, for closely similar species can be put together to make up a genus. The genus Canis includes the wolf (Canis lupus), coyote (Canis latrans), golden jackal (C. aureus), and others. Genera that appear related are then grouped into a family, so that family Canidae includes such genera as Canis, Urocyon, and Vulpes (foxes). Related families constitute an order; e.g. families Canidae, Felidae (cats), Ursidae (bears), and others are grouped together into order Carnivora, flesh-eating mammals with fang-like canine teeth. All orders of mammals are grouped into the class Mammalia: hairy, milk-producing vertebrates. The vertebrate classes, including Amphibia, Reptilia, Aves, and Mammalia, among others are grouped into the subphylum Vertebrata, animals with backbones, which are allied with other animals that have an embryonic supportive rod called a notochord, to make up the phylum Chordata.

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