Tuesday, December 1, 2020

Speculative Evolution: Teegarden's Star B - Part I: Deathly Light & Wine-Dark Seas

The variety of forms life has taken past and present, and the processes that gave rise to those forms, are really fucking cool. I had a DM try to explain to me what a red panda was the other week. I know what a red panda is. I've been to a zoo.

A natural extension of my interest in real forms of life then is speculative evolution, using what we know about biochemistry, evolutionary pressures, and the like to better imagine how life might develop on other planets (or alternate branches of our own planet's history) in a more-or-less plausible fashion. Here's some links to some of my favourite speculative evolution projects:

The Future is Wild: https://www.youtube.com/watch?v=Rbi8Jgx1CNE

Snaiad: http://www.cmkosemen.com/snaiad_web/snduterus.html

Biblaridion's Alien Biospheres series: https://www.youtube.com/watch?v=egzZv8tqT_k&list=PL6xPxnYMQpquNuaEffJzjGjMsr6VktCYl

The Epona newsletter: http://worldbuilders.info/epona/

The world of Serina: https://sites.google.com/site/worldofserina/home

The Planet Furaha blog: http://planetfuraha.blogspot.com

The Ilion blog: https://sunriseonilion.wordpress.com/ilion/

This post is intended to be the first in a series of a speculative evolution project of my own. This project will be loosely based on the planet Teegarden's Star B, a recently discovered exoplanet with one of the highest Earth Similarity Index Scores of any known exoplanet thus far.

What we know about the planet is: that it's located about 12 light years from Earth, it orbits a red dwarf, it's got an orbital period of 4.91 days, its mass is possibly 1.05 times Earth's, its insolation is about 1.15x times Earth's, and its temperature would enable liquid water to exist on its surface. Everything else from here on out is my own invention.

There's some issues with the development of life around a red dwarf. Firstly, given how close the Goldilocks's Zone would have to be to such a star, it's possible that any planet in the Zone would be tidally locked to the star. This would mean a constant heat on one side, and utter cold and dark on the other, potentially freezing any atmosphere that develops. Secondly, red dwarf stars tend to output a lot of solar flares. Teegarden's Star B is distinct in that it appears to be relatively calm.

Perhaps in defiance of God and astrophysics, I'm going to say that my TSB is not tidally locked. It has a smaller axial tilt than Earth (leading to less differentiated seasons) and rotates in such a way that gives it a 40-hour day/night cycle. That makes its year a bit shy of 3 TSB days, which is sure to frustrate some calendar-makers, and make some French philosophers very happy.

To add some spice to our primordial soup I'll suppose that some billions of years past Teegarden's Star was feistier, giving off the solar flares and bursts of ultraviolet radiation of most red dwarfs. This will tail off with time but during the period this post is looking at life will largely be constrained to several meters below the ocean surface, deep enough to be shielded from the worst of the star's wrath. In this submarine shelter the living kingdoms which will share the world to follow have formed:

(If you know any Latin or Greek please correct my naming in the comments, I'm just using google translate)


Living fossils even here at the harsh dawn. Once the predominant form of life on the plant, now reduced by the evolution of multicellularity and predation to mere bit players.

Thermidoria is distinguished by two main attributes: thermosynthesis, and multiple nucleui.

Most thermidorian lifeforms are capable of deriving energy from thermal gradients (though this energy is minuscule compared to photosynthesis). Despite being at a severe disadvantage with energy production you can find them pretty much everywhere. The aphotic ocean depths are often a wasteland on Earth, but on TSB they abound (relatively speaking) with slow jungles of thermidorians.

All thermidorians are unicellular. Many are also visible to the naked eye. Among their adaptions that make them capable of achieving this is that their cell has multiple nuclei, as well as internal partitions, often made from incorporated inorganic matter, and the thinness of their body structure.

Notable clades of Thermidoria in this era include:

Nimates: Primitive even among the primitive kingdom, nimates are pure thermosynthetes, resembling long plastic strands hanging in the water. They lack the metabolic capacity for self-driven movement, relying on concentrating inedible and toxic materials in their cell walls and sheer ubiquity for survival.

Anoterosia: A planktonic group which hosts much smaller symbiotic algae in their cell walls and partitions. Of all life on TSB they are the clade which lives closest to the surface, having a number of adaptions including nucleic redundancy to resist the high level of ultraviolet radiation. In the billions of years to come the descendants of the anoterosians will form the basis of perhaps the most un-Earthly of all TSB's biomes.

Koubanites: One of the truly rare heterotrophic thermidorian clades, containing both mobile and sessile predatory and filter-feeding species. Most resemble gelatinous bells lined with cilia, with a frontal orifice that can cinch shut.


Descended from a species of multicellular phytoplankton with silicate shells, similar to Earth's diatoms. The kingdom Diaphania contains two branches, one of plant-like phototrophs and one of animal-like heterotrophs that lost their chloroplast-analogues. Both branches share the characteristic support/protective organ "siliceous laminate", layers of cartilaginous membranes impregnated with silicon in various formations and concentrations. This creates an effect akin to pattern welding, allowing siliceous laminate tissue to achieve the ideal mix of flexibility and hardness for a given use.

Rather than both sexes producing gametes, only one diaphanian sex does. The other grows haploid buds which if not fertilized may still grow into adult pseudo-clones of the budding parent.

Diaphanian phototrophs utilize several pigments to wring the most out of their red and blotted sun, some provided by symbiotic microorganisms, all much darker than the chlorophyll we're used to. The mixture of near-black purples, yellows, reds, and greens makes them appear like necrotic tissue to our eyes.

Notable clades of Diaphania in this era include:

Alexiophylls: Also called parasol kelp. They resemble seaweed, even growing in underwater forests that home entire ecosystems, except for two features that would stand out to even the untrained observer. The first is their namesake: a cluster of lenses that float above their main body, shielding it from the worst radiation, allowing them to grow above their competitors and closer to the light. The second is a "reel" which anchors them in the seabed. When the organism detects a dangerous increase in temperature or radiation, the reel pulls it down deeper beneath the water's protection.

Kastrophylls: Also called coral-moss. The very first pioneer of TSB's land. Without water to rely on for protection, coral-moss instead grows a translucent crust to filter out the most harmful rays. Over many generations this can create glassy mounds filled with pseudo-vascular tubes that draw water up to the living coral-moss. These mounds will shelter the terrestrial animals to follow.

Kolliofacia: Worm-like burrowing creatures with a U-shaped digestive tract passing around their hemocoel, mouth and cloaca ending up much too close for most Earthlings' liking. Beneath this they've got a muscular digging "foot" lined with lateral spines or bristles, and their "head" bears jointed opercula and a bouquet of feeding/sensory tendrils.

Dontiderms: A group which branched off from the kolliofacia as that clade adapted more to filter-feeding. They resemble flattened lancelets, only rather than cirri they possess a mouthful of grinding and scraping teeth, some of which have migrated or been replicated elsewhere on their body, forming armour much like osteoderms. Dontiderms can be further subdivided into those species which evert their mouths and teeth into something like an external gizzard to feed, and those with muscular lips to pluck food or create suction. The clade was the first to develop genuine eyes, though given the long night sight tends to be underdeveloped as a sense compared to Earth.


Like Diaphania, the kingdom Tomatrichia contains branches that on Earth would be distinct as Animalia, Plantae, and Fungi.

The basal ancestor of Tomatrichia is a creature somewhere between fungus, slime mold, and biofilm: a zoogleal mass of microorganisms that cooperate to construct mycelia-like structures with keratinous cell walls, sometimes dismantling each other and merging for the raw materials. These mycelia in turn grow spawning bodies that produce more of the mass. From this base the kingdom has diversified into two animal-like branches, one similar to sponges, and the other similar to echinoderms, various saprophytic and parasitic forms, and a photosynthetic form which absorbed chloroplast-analogues from a diaphanian host.

Most trichian species have mating types rather than sexes as we'd recognize them, up to thousands of different types in some. More mobile species tend to have fewer mating types.

Notable clades of Tomatrichia in this era include:

Laspikoroids: Parasites on the anchors of parasol kelp. Laspikoroids don't deviate much from the tomatrichian basal form, except that their zoogleal form can produce a potent toxin similar to botulinum. They also entrap and digest other creatures which would nibble on those anchors.

Nychaspidoids: A group that looks like something between sea stars and chitons, a radially symmetric set of feet with segmented keratin armour on top. Nychaspidoids feed by vomiting a zoogleal mass onto their prey, which externally digests it and is then slurped back up into the main body. They do something similar to breed. Some species within the clade undergo a process of "enfolding" as they mature, their armour bending and fusing to encompass an entire limb.

Nouvatoids: A group resembling fuzzy sea urchins. Unlike sea urchins they lack tube feet and an Aristotle's lantern, while their spines are articulated and can be bent to serve as legs. Like the nychaspidoids their zoogleal form has been reduced to specialized internal nodes that perform neuronal, digestive, and stem cell-like functions. Under certain conditions, mostly related to high population density, nouvatoids will overgrow their fuzz and roll around to disperse like underwater tumbleweeds. Nouvatoid young perform a similar behaviour, only with a single overlong thread.

Ziztrypoids: A highly-derived clade that began from a species of tomatrichian that produced a mushroom-like fruiting body. The fruiting body was porous to allow spores within it to catch a current, but the current also brought in microorganisms which were sometimes consumed. Eventually the fruiting body was adapted from a temporary reproductive measure into the main body of the creature, with the mycelium serving only to stick it in place.

There's analogues to viruses and bacteria and all that too, but I'd find coming up with that stuff boring. Assume that sort of thing exists outside of this project's spotlight, which I'll tend to focus on charismatic fauna & flora. Next time there might even be pictures.


  1. Hell fucking yes to all of this.

  2. Have you ever read Gould's book Wonderful Life? It has some fascinating insights on the Cambrian Explosion and what we can learn from it about evolution more broadly.

    1. No but from a quick google search I'd say I broadly agree with his argument re: contingency. There's universal constraints like the square cube law and so on (we're probably not going to see macroscopic animals that fly using lighter-than-air gas), and some features that have evolved independently so many times on Earth that we'd probably see them in alien life (e.g. eyes, venom). Beyond that it's hard to say with any certainty how alien life might turn out.

  3. This is all very cool, I'm also a fan of speculative biology / speculative evolution but this is much better researched and realized than what my biology and chemistry knowledge would allow lol. I'm really interested to see where this goes.

    You've mentioned the idea of plastic-like organisms before so I'm glad to see that come into play here.

    Even besides just understanding the science on some level, another thing that I think can make speculative evolution interesting but also difficult, is where it heavily diverges from anything we have any frame of reference for. It's almost, but maybe not quite, like trying to imagine what ultraviolet would "look" like if our eyes or another sensory organ could "see" in that range. What would a species look like that isn't plant, animal, fungus, etc.? Or what would an "animal" look like that isn't a mammal, fish, amphibian, reptile, bird, etc.? It's just a difficult thing to even conceive of, with or without good science, let alone explain coherently and make into a game or narrative.

    All of that said, that's exactly why I find it so interesting ;)

    1. My knowledge of the actual science stuff doesn't go much deeper than a wikipedia search would, otherwise I'd probably go further up my own ass trying to come up with alternatives to DNA or proteins or something.

      With regard to divergence I feel it's a "know the rules before you break them" sort of thing. Part of the speculative evolution appeal to me is the wonder that all these wild creatures are technically possible, somewhere and somewhen. I've got some out there ideas for the directions TSB will take, but ultimately it's very close to Earth in terms of global conditions. Significant differences in temperatures, seasonality, chemistry, gravity, nychthemeron length, and so on and so on would lend themselves to greater biological divergence. That being said I think we have strong reason to believe that fast-moving aquatic predators, whether they're swimming through water or ammonia, will be torpedo-shaped, though even within that we've got everything from sharks to squid. Ditto for large terrestrial phototrophs and leaf-like structures. A world that allows for autotrophs that draw power from a planet's magnetic field though? All bets are off.