Living beings are classified into groups with common characteristics, which are currently:
Kingdom
Phylum
Class
Order
Family
Gender
- Species
Since prehistoric times, when we were still discovering our ability to communicate, man already felt the need to classify biological organisms.
However, it was only in the 18th century that the scientific bases of the branch of biology that classifies and organizes living beings into categories emerged: Taxonomy. This classification still follows a system defined in 1735 by the Swedish botanist Carl Von Linné, also known as Linnaeus.
Linnaeus grouped biological organisms according to their common characteristics into groups called taxa, ranging from the most comprehensive to the least comprehensive:
Kingdom > Phylum > Class > Order > Family > Genus > Species
The kingdom, the most comprehensive of the taxa, brings together phyla with similar anatomical, structural and genetic characteristics.
The phyla, in turn, group the classes, which encompass the orders, which encompass the families, which encompass the genera.
Finally, the genera incorporate the species, the least comprehensive taxonomic category, defined as one that brings together organisms that reproduce among themselves and that are capable of generating offspring fertile.
Superrealms or Domains
Some authors still consider the existence of a taxon superior to the kingdoms, the super realms or Domains, which would be three: Bacterium, archaea and eukarya.
The biological realms
For Linnaeus, in the 18th century, there would be only two kingdoms: animal and plant. However, with the advancement of time and the evolution of microscopy, new realms were discovered. Currently, there are five biological kingdoms:
monera
protist
fungi
animalia
plant
THE kingdom monera It is composed of unicellular microscopic organisms (formed by a single cell) and prokaryotes (cells that do not have an organized nucleus). Bacteria and blue algae or cyanobacteria are part of this kingdom.
THE kingdom protista or protoctist is formed by eukaryotic beings (the nucleus of the cell is defined and surrounded by a membrane) mostly microscopic. They can be unicellular or multicellular (made up of more than one cell). Algae and protozoa belong to the kingdom protista.
THE kingdom fungi is made up of fungi, which have a cell wall formed by chitin. They can be unicellular or multicellular. The best known fungi are mushrooms, mold formers, molds, wood ears and yeasts (biological yeast).
THE animal kingdom, animal or metazoa covers all animals on the planet. They are macroscopic, eukaryotic and multicellular beings. It consists of nine main groups (phyla):
- Porifera or sponges (sea sponges)
- Cnidarians or coelenterates (jellyfish)
- Flatworms (tapeworms, planarians)
- Aschelminths (roundworms)
- Annelids (earthworms, leeches)
- Molluscs (squid, octopus, oysters)
- Arthropods (bees, spiders, crabs)
- Echinoderms (starfish, sea urchins)
- Cordates (dogs, frogs, swallows)
THE kingdom plantae, vegetable or metaphyta contains organisms that produce their own food (autotrophs) through photosynthesis. They are eukaryotes, multicellular and have aerobic respiration (uses oxygen as the final acceptor). As examples, we have pine trees, ferns and rose bushes.
Example of taxonomic classification
Let us now take, as an example, the taxonomic classification of the human species:
Kingdom: animalia
Phylum: Chordata
Class: mammalia
Order: Ape
Family: Hominidae
Gender: Homo
Species: Homo sapiens
Scientific names: binomial nomenclature
In addition to classifying living beings into categories (taxa), Lineu also standardized the way of naming species, adopting a system used to this day.
According to Linnaeus, the scientific name must be in Latin, a language considered universal and also dead, not allowing new changes.
The names of the categories from kingdom to genus must be unique, that is, have only one word, and must be capitalized.
The species must be binomial, that is, they must have two names, formed by joining the genus (generic epithet) with the species (specific epithet), which must be written in all lowercase letters. Take the example of the human species:
Homo (generic epithet) + sapiens (specific epithet) = Homo sapiens
The scientific name must also be highlighted in the text, having to be written in bold, italics or underlined.
Evolution of taxonomy
- 1735: publication of the book Systema Naturae, by Linnaeus, which lays the foundations of taxonomy.
- 1969: American botanist Robert Harding Wittaker proposes a new classification of organisms into five kingdoms, which is the classification currently adopted.
- 1977: Carl Richard Woese, professor of microbiologist at Yale University (USA), indicates the existence of a taxonomic category superior to the kingdom, the domain.
See too:
- Characteristics of living beings
- taxonomy
- animal Kingdom
- Biology
- Homo sapiens
