26.2. Classification of Living Beings: Taxonomy

The classification of living beings, also known as taxonomy, is an area of ​​Biology that is dedicated to the study of biological diversity, its organization and its relationships. Taxonomy is fundamental for understanding life on our planet, as it allows us to identify, name and classify living beings according to their characteristics and evolutionary relationships.

The system for classifying living beings was first proposed by the Swedish scientist Carl Linnaeus, also known as Linnaeus, in the 18th century. Linnaeus established the basis for modern taxonomy by introducing the binomial system of nomenclature, in which each species is identified by two names: the first referring to the genus and the second to the species. For example, the scientific name for humans is Homo sapiens.

Currently, taxonomy organizes living beings into a hierarchy of taxonomic categories, ranging from the most general (the domain) to the most specific (the species). The main levels of classification, in descending order, are: Domain, Kingdom, Phylum, Class, Order, Family, Genus and Species.

Domains are the broadest category of biological classification and divide living beings into three major groups: Bacteria, Archaea and Eukarya. Bacteria are unicellular, prokaryotic organisms and can be found in almost all environments on Earth. Archeans are also prokaryotes, but they differ from bacteria in several molecular and biochemical ways. Eukaryotes include all organisms whose cells have a cell nucleus, including animals, plants, fungi, and protists.

Within the Eukarya domain, we find the four kingdoms: Animalia, Plantae, Fungi, and Protista. Kingdom Animalia includes all animals, multicellular beings that feed on other organisms. The kingdom Plantae comprises plants, which are multicellular organisms that produce their own food through photosynthesis. Kingdom Fungi includes fungi, which are organisms that feed on dead or living organic matter. And the kingdom Protista is a diverse group that includes all eukaryotes that don't fit into the other three kingdoms.

The levels of phylum, class, order, family, genus, and species become progressively more specific, grouping together organisms that share increasingly particular characteristics. For example, within the kingdom Animalia, the phylum Chordata includes all animals that possess a dorsal cord at some stage of their development. Within this phylum, the class Mammalia includes all animals that have mammary glands, such as humans, dogs and cats.

In summary, taxonomy is an essential tool for biology, as it allows us to understand the incredible diversity of life on our planet. It helps us identify the similarities and differences between living things, understand their evolutionary relationships, and communicate this information clearly and consistently.

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