biological kingdoms

biological kingdoms

Biological kingdoms are a way of classifying and organizing the diversity of life on Earth. In nature, there are a large number of living things that exhibit a wide variety of characteristics and functions. To understand and study this diversity, scientists have developed a classification system based on similarities and differences between organisms.

Therefore, in this article we are going to tell you everything you need to know about the biological kingdoms, their characteristics, types and much more.

Origin and evolution of biological kingdoms

kingdom plantae

The earliest systems of classifying life date back to distant times, when ancient philosophers devised approximations to life by distinguishing between its fundamental observable properties. Therefore, we have:

  • Two kingdom system. Attributed to the Greek philosopher Aristotle (IV BC), it divides living beings into two large groups based on what theorists call "vegetative souls" and "sensitive souls". In the first case it translates into the ability to grow, nourish and reproduce, while in the second this also includes desire, movement and perception. This system was later followed by the famous Swedish scientist and naturalist Carlos Linnaeus, who in 1735 proposed a classification system for two domains: Planta and Animalia.
  • System of the three kingdoms. The third kingdom would appear for the first time in 1858, when the English biologist Richard Owen realized the difficulty of classifying certain microorganisms according to the two kingdoms of Linnaeus and proposed a third kingdom: the protozoa, made up of nucleated cells. This new kingdom was renamed Proctista in 1860 by his compatriot John Hogg, although in his considerations he also proposed the existence of a "mineral kingdom" later dubbed the "Father of Protobiology" excluded by Ernst Haeckel, who in 1865 named the Third Kingdom called Protista, which includes all forms of microscopic life with characteristics of animals, plants and hybrids, but for the first time distinguished single-celled organisms and multicellular organisms.
  • Four kingdoms system. As microbiology progressed, it was necessary to rethink the system of the three kingdoms, as the distinction between prokaryotes (without a nucleus) and eukaryotes (with a nucleus) became more evident and important. To distinguish nucleated from anucleated microbes, Herbert Copeland in 1938 proposed a system of four kingdoms: Animalia, Plantae, Protozoa, and a new Group of anucleated bacteria: Monera.
  • System of the five kingdoms. The fifth kingdom appeared in 1959, when Robert Whittaker confirmed that fungi were an entirely different group from plants, and proposed a five-kingdom system that included Fungi (fungi) in 1969, while retaining Copeland's four kingdoms. This is one of the most popular systems ever.
  • Six kingdom system. Advances in DNA and RNA discovery and research techniques in the second half of the XNUMXth century revolutionized many assumptions in biology and allowed Carl Woese and G. Fox to reinvent the system and propose six distinct kingdoms: bacteria, archaea, protists, plants , animals and fungi These six kingdoms are divided into two domains: prokaryotes (bacteria and archaea) and eukaryotes (the rest). In many places, this is the accepted system.
  • System of seven kingdoms. The work of Cavalier-Smith, Canada, and later developers, who proposed the creation of the kingdom Chromista to distinguish diatoms, oomycetes, and similar algae, and to restore the name Protozoa to the remaining eukaryotic microbes. Thus, the seven kingdoms would be two of the prokaryotes: archaea and bacteria, and five of the eukaryotes: Protozoa, Chromista, Plantae, Fungi, Animalia.

biological kingdoms

division of biological kingdoms

Kingdom Bacteria

One of the two main kingdoms of prokaryotes, that is, there is no nucleus, and the cell structure is simpler and smaller, including the most abundant and diverse single-celled microscopic organisms on earth, existing in photosynthetic, saprophytic, and even modes parasites and are in the world in almost all habitats. They have a peptidoglycan wall and can be divided into two types: Gram-negative (they have a double wall) or Gram-positive (they have a single wall).

Kingdom Archaea

This is another known prokaryote that lacks a peptidoglycan cell wall, is non-pathogenic, and exists in very extreme habitats because its nutrition is based on chemosynthesis, that is, using specific chemical reactions in an anaerobic environment (in the absence of oxygen). Archaea, or archaea, have been known to exist since the XNUMXth century, but it wasn't until the XNUMXth century that people understood how they differ from bacteria.

Kingdom Protozoa

This kingdom is considered the base group of eukaryotes, that is, the first to emerge from which other organisms would later separate. It is a paraphyletic group, that is, it includes the first common ancestor but excludes all its descendants.

Here, then, we can find eukaryotic unicellular microorganisms, generally with flagella, without cell walls, do not form tissues, specialized in heterotrophic nutrition, either saprophytes or predators of other microorganisms such as bacteria and other protists.

Chromista Kingdom

types of bacteria

It is a kingdom of eukaryotes that does not share many common features, but this can be generalized to various types of algae that are traditionally classified as either the plant kingdom or fungi because they may or may not contain chlorophyll or other pigments. In fact, many chromists can lead parasitic lives. This group includes unicellular and multicellular algae, oomycetes, and apicomplexes.

Kingdom Plantae

A group of multicellular eukaryotes that carry out photosynthesis, that is, they carry out the synthesis of sunlight, absorbing atmospheric carbon dioxide and releasing oxygen in return. This group is integral to the support of life as we know it, especially land plants. They are characterized by having cells with cellulose walls, fixed life and sexual or asexual reproduction depending on the species and given conditions.

fungi kingdom

It is composed of aerobic and heterotrophic multicellular eukaryotes, they cannot synthesize their nutrients and therefore they dedicate themselves to a saprophytic or parasitic existence: they act as decomposers of organic matter or infect the bodies of other organisms. They have cell walls like plants, but made of chitin instead of cellulose, and they reproduce sexually and asexually by spores.

Animalia Kingdom

The last kingdom is that of animals, the kingdom of eukaryotic multicellular organisms with their own motility and heterotrophic metabolism, maintained by respiration: consuming oxygen and organic matter from other organisms to oxidize and gain chemical energy and excrete carbon dioxide. Animals are an extremely diverse kingdom spanning aquatic, terrestrial, and even airborne habitats and can be divided into two main groups, vertebrates and invertebrates, depending on whether they possess a backbone and an endoskeleton.

I hope that with this information you can learn more about the biological kingdoms and their characteristics.

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