Biospheric Classes

The Terragenid group is classified as organic multicellular lifeforms, of both marine and terrestrial biomic types. However, a significant percentage of terragenids are unicellular, and the planet has a poorly-studied aerial biome.
— Example biospheric classification
Life is a fundamental concept in a universe which happens to be relatively teeming with it. The nature and definition of life have been debated over and speculated upon by the philosophers and scholars of all sophont species throughout spacetime. At the formation of the United Spacefaring Sophonts Coalition, a solid universal definition of life and biospheric classification system was agreed upon to discourage the potential for discrimination later on and help biologists better understand their field of study. Under this definition, life is characterized by the following attributes:
  • The ability of the entity in question to consistently regulate its own internal entropy.
  • The ability of the entity in question to replicate all or parts of itself, independently, regardless of the type of biophysical unit replicable; or the ability to reproduce sexually; or the ability to replicate its consciousness.
  • Inertia-independent reaction to stimulus, however slight and regardless of speed.
  • The independent production or collection and internal storage of energy for self-use, including but not limited to: active biological molecular processes[1], capacitor structures, nanoscale electrothermal turbines, etc.

Biosphere Classification System

A planet's biosphere, if it has one, has a fairly simple classification system of its own, determined by a few key factors.  


Beyond the general biotic class system, a new tier of taxonomy was added to the extant phylogenetic system to denote the different abiogenetic origins of organisms. Genesis groups are a rank above Domain intended to separate the myriad trees of life across known space by indicating where their abiogenesis[2] took place. The skae of the planet Ra'na in the Tau Ceti system, for example, have a taxonomy that looks something like the box to the left.   Any clade within a genesis group that parallels a terragenid clade has that same name applied but with an abbreviation of its genesis group tacked on the end to prevent confusion. In the uncommon cases of panspermia[3], panspermic notations are used to indicate the phylogenetic point at which the interplanetary migration occurred.

Skae Phylogeny

Ranagenids (genesis group)
  • EukaryaRN (domain)
    • AnimaliaRN (kingdom)
      • Placospondyla (phylum)
        • HexapodaRN (superclass)
          • Terrambulatis (class)
            • Arthrodactyla (order)
              • Centauridae (family)
                • Xenocentaurus (genus)
                  • sapiens (species)



In the broadest sense, organic life is based on the interactions of carbon and carbon compounds. It is the most common type of life in known space, due to carbon's commonality, but the element's versatility results in a vast array of carbon-based biospheres that are nigh irreconcilable with each other.   The kelmigenids, for example, have evolved on a titanoid world whose methane solvent cycle and icy geology have produced a biochemical system radically different from, for instance, terragenids. This biochemical diversity is potentially catastrophic for first contact events, though stringent measures have been taken to prevent such a disaster.


The term exotic in the context of biospheres refers to any form of life not based on carbon. While not as common as carbon-based life, a significant portion of the genesis groups in known space are exotic, based on such elements as silicon, nitrogen, phosphorus, boron, arsenic, and ammonia.   Even within these known bases, there is a considerable extent of structural variation due to environmental diversity, as expected from a sample size of 270 star systems. Still more types of exotic life exist purely as hypothetical concepts, such as organisms based on lead, hydrogen sulfide, heteropolymic acids, and even radio pulses.




by National Science Foundation

Protocellular lifeforms are a rare but incredibly varied class of organisms that meet only some of the criteria for life. This may come in the form of self-replicating polymers, free RNA or RNA analogues, or lipid clusters which perform metabolism but cannot replicate. These first recognizable signs of life are typically found on young, solvent-rich worlds with active suns. Protocellular organisms form extremely simple relationships with each other and their environments.


youth maturity unicellular algae.png

by Ye Maltsev

Unicellular lifeforms are by far the most common form of life in known space; roughly two-thirds of all documented biospheres are entirely comprised of single-celled organisms. This is not to say that planets with more complex life are devoid of unicellular life; quite the opposite in fact. As the hardiest biostructural class, single-celled life can be found on almost every known type of planet. Unicellular organisms form fairly simple relationships with each other and their environments.


Blue Dasher Dragonfly.png

by Bonnie Taylor Barry

Multicellular lifeforms are the second most common form of life in known space, trailing behind unicellular life by half. It is the broadest category of organism structure, with organisms ranging from sophonts to Poseidonic orbmoss fitting under the multicellular umbrella. Complex life is found on older planets whose geology and solar activity have mellowed. Multicellular organisms form complex relationships with each other and their environments, giving rise to visible macroecology.



Terrestrial biospheres are a fairly common biomic type comprised of life that primarily dwells on (or, more rarely, within) the solid surface of their homeworlds. This type of biosphere is found most frequently on terrae, though numerous desert worlds have limited terrestrial life as well. Terrestrial biospheres are typically macroecological as well as microecological, and are one of the more diverse biomic types in terms of biochemistry and evolution.  


Marine biospheres exist solely within liquid solvent on a planet's surface. Marine life is the most common biomic type, of course, being found quite commonly on oceaniae, terrae, and titanae. However, the line between marine and aerial biomic types is blurred in the cases of supercritical atmospheres such as those on oceaniae and neptuniae, which are something between ocean and sky. Marine life typically resides in water oceans, though hydrocarbon- and ammonia-housed marine biospheres are known to exist.


Subglacial biospheres are characterized by their existence underneath or even within the solid icy crust of their homeworlds. This biomic type occurs almost exclusively on cryonic planets, though a few titanae have subglacial life as well. This biomic class is most often similar to marine life, as life on cryonae typically subsist within oceans. However, subglacial life is distinct in its lack of contact with the sea's surface, as the interior ocean directly borders the ice above it.  


Aerial biospheres are the strangest biomic type in all of known space, as they are composed entirely of organisms that spend their whole lives airborne; either volant, aerobuoyant, or both. This type of biosphere is only found on joviae and neptuniae, with the sole exception of the venusian planet Nuyo in the Gliese 754 system. Because of this, known aerial biospheres are almost always exotic in chemical composition, needing to rely on unusual metabolism to survive in the volatile atmospheres of giant gaseous worlds.


[1] Active biological molecular processes are defined as: the intake, internal reaction, and output of chemicals between the environment and the entity in question.
[2] Abiogenesis is the natural spontaneous development of biology from an abiotic environment.
[3] Panspermia is the interplanetary spread of one kind of life from its abiogenetic homeworld to other places in the cosmos, naturally by impact ejecta but more frequently by artificial means.  

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Master Redclaw123
Elias Redclaw
11 Jun, 2019 17:14

Holy space! This was a beautiful article! I am jealous at how well you can describe the technical and scientific aspects of this article! Its beautifully formatted with some gorgeous artwork too! I would say that this is a great example of a primer article as well. Congrats mate and keep up the great work!