Biological classification is the organization of living things into groups based on their similarities and differences. It’s like filing books in a library — you group them by genre, author, or publication date to make them easier to find and understand.
There are many different ways to classify organisms, but the most common system is based on a hierarchy of groups called taxa. The largest taxon is the domain, and then there are kingdoms, phyla, classes, orders, families, genera, and species.
Each taxon is defined by a set of shared characteristics. For example, all animals belong to the kingdom Animalia, which is characterized by multicellularity, heterotrophy (they must eat other organisms for food), and the ability to move.
The five kingdoms of the most common classification system are:
- Animalia: Animals (multicellular, heterotrophic, motile)
- Plantae: Plants (multicellular, autotrophic, non-motile)
- Fungi: Fungi (multicellular, heterotrophic, non-motile)
- Protista: Protists (mostly unicellular, diverse modes of nutrition)
- Monera: Bacteria and archaea (unicellular, prokaryotic, diverse modes of nutrition)
Biological classification is the organization of living things into groups based on their similarities and differences. It is a way of making sense of the diversity of life on Earth.
- The basic unit of classification is the species. A species is a group of organisms that can interbreed and produce fertile offspring.
- Species are grouped into genera, genera are grouped into families, families are grouped into orders, orders are grouped into classes, classes are grouped into phyla, and phyla are grouped into kingdoms.
- The most common classification system used today is the three-domain system. This system classifies all living things into three domains: Bacteria, Archaea, and Eukarya.
- The Bacteria and Archaea are both domains of prokaryotes, which are organisms that do not have a nucleus or other membrane-bound organelles.
- The Eukarya are the domain of eukaryotes, which are organisms that do have a nucleus and other membrane-bound organelles.
- Eukaryotes are further divided into four kingdoms: Animalia, Plantae, Fungi, and Protista.
- The Animalia kingdom includes all animals, such as humans, dogs, and insects.
- The Plantae kingdom includes all plants, such as trees, flowers, and grasses.
- The Fungi kingdom includes all fungi, such as mushrooms, molds, and yeasts.
- The Protista kingdom includes all protists, which are eukaryotes that are not animals, plants, or fungi. Protists are a very diverse group of organisms, and they include things like amoebas, paramecia, and algae.
Here is a table that summarizes the three-domain system of classification:
Domain — BacteriaProkaryotes;
Description — cell walls made of peptidoglycan
Examples — Escherichia coli, Staphylococcus aureus
Domain — ArchaeaProkaryotes;
Description — cell walls not made of peptidoglycan
Examples — Halobacterium sanitarium, Methanococcus macrophiles
Domain — EukaryaEukaryotes;
Description — have a nucleus and other membrane-bound organelles
Examples — Animals, plants, fungi, protists
Biological classification is a complex and ever-changing field. Discoveries are constantly being made, and the classification of some organisms is still being debated. However, the basic principles of classification remain the same: to group organisms based on their similarities and differences.
Originally published at https://www.vhtc.org.
