Biosemantics

Biosemantics is the academic discipline of classifying and naming organisms based on physical and physiological characteristics. The definition of this field is often broadened to include systemic analysis of the classification structure, philosophy of nomenclature, and integration of biological terminology into the vernacular Tetrian language. Phylogenetic Taxonomy is the closest field to biosemantics that exists on Earth, although biosemantics is generally much broader and has more applications outside of the academic community.

Domains
Nomenclature of Tetrian life-forms follows a pattern similar to Earth's biological classification system, Phylogenetic Taxonomy. The first level of organization, domain, differentiates life-forms based on their mode of obtaining energy. As you can see, the recently revised Tetrian system is designed to coincide with Earth's system at the domain level, such that the human-devised domains represent distinct energy-production methods from the Tetrian domains, allowing the two systems to be seamlessly combined into a single organizational structure which encompasses all known life-forms.

Eukarya

 * See main article: Eukarya

The human-devised domain Eukarya includes all life-forms that produce energy through a cellular metabolic process using oxygen, glucose, and water as the primary reactants. This domain will at some point need to be modified to include those life-forms that currently constitute the domain Bacteria, since these organisms produce their energy by the same means, despite their lack of a nucleus.

Pyrona

 * See main article: Pyrona

Pyrona, the most extensive domain found on Tetro, consists of organisms that obtain energy through the combustion of any readily available material. The material is acquired by absorption or ingestion into a gastric cavity where it is kept burning continuously, creating heat energy which can be harnessed by the organism in a variety of ways.

Photona

 * See main article: Photona

The photonates obtain their energy by converting light into electrical energy via light-activated organelles. This electricity is used to electrolyze water into its component molecules of hydrogen and oxygen, which are combusted to provide the organism with the heat energy that it is ultimately able to use.

Magneta

 * See main article: Magneta

The bodies of magnetates are filled with immense quantities of coiled conductive material in which electrical current is induced when the organism is in close proximity to the magnetic field of a planet or star that is moving relative to it. Water ingested or absorbed by the organism and stored in the body is electrolyzed and combusted by the electricity, in the same way as in photonates.

Kingdoms
Each of the domains is subdivided into three kingdoms, based on how the organism harnesses the heat energy it creates.

Exopropata

 * See main article: Exopropata

The kingdom Exopropata consists of species that propel themselves by expelling jets of hot air from openings on their bodies, propelled by the organisms' heat-generating metabolism. A circulatory system within their bodies also uses inhaled air to open and close valves that control the functioning of almost every internal organ including the brain, which is a massive network of minuscule, interconnected tubes and valves.

Endopropata

 * See main article: Endopropata

Endopropates have a circulatory system similar to that of the Exopropates, but which uses water, propelled by the organisms' heat-generating metabolism. The circulating water is used to fill and empty various cavities in the body which expand and contract to move joints.

Apropata

 * See main article: Apropata

Apropata contains organisms that are largely immobile, similar to constituents of the kingdom Plantae on Earth. These organisms have no cognitive abilities, lacking the valved circulatory system necessary to power a brain. The only domain known to contain Apropates is Photona.

Phyla
Each kingdom is further subdivided into phyla based on evolutionary relationships between individual species.

Species
Tetro is home to 25 species of living organism, shown with their classification in the chart below.