My exobiology project: The Yagarian System

I always wanted to do a speculative biology project, but I never had enough motivation or patience, but I decided to change that and do it now! I did the planets images in spaceengine, and some help is always welcome!


The Yagarian System. Centered on Yagari, a K1V class orange dwarf, it contains four planets:

Tidal-locked, Farnu has an average temperature of 220~ Celsius, and a dense atmosphere, composed mostly of CO² and some fractions of nitrogen.

A Gas Giant slightly smaller than Jupiter, having 8 Earth radii. It is located within the habitable zone of the system. It has a small but dense ring system, as well as three sizable moons:

Kioka: Kioka is the closest moon to Latana, and has a surface dotted with deep impact craters, caused by an encounter that Latava had with a small asteroid belt during the system’s formation. The asteroids suffered a gravitational slingshot effect and hit the poor Kioka.

Netarai: This could be considered the least interesting moon among the three, but it contains something worth noting: Its surface is covered by organic matter, giving it a dark brown color. The view is great, too.

Bhafa: The furthest moon from Latava is surprising, the only one with an atmosphere and liquid water. As previously mentioned, Latava is located in the habitable zone, and as Bhafa already had a good iron core, it is enough to maintain a its surface covered in liquid water.

A perfect world for the emergence of life. Large oceans, some islands with a strangely high amount of pink Granite on their terrain. It has two large polar ice caps, larger than the Earth due to their distance of 1.3 AU from Yagari. Furthermore, it has a gravity of only 70% that of Earth, which will give us the opportunity to see some interesting megafauna…
Ceatrus has two moons:

Wilba: A small moon near Ceatrus. It has large amounts of Uranium in its composition. This will be important in the future, very useful in the future…

Lana: The second “moon” of Ceatrus, being a third the size of Ceatrus it can be considered a binary system. Lana has a thin atmosphere and a surface covered in iron oxide, in addition to a large amount of water frozen in their caps. It resembles a certain red planet located in the Orion arm of the Milky Way, but no one cares.

The furthest planet from Yagari. It has a thick atmosphere and large lakes of liquid nitrogen on its surface. Oh yeah, and it has an UNNECESSARY LARGE RING SYSTEM, BECAUSE I WANT OK? DONT JUDGE ME
Tiratas has two moons:

Pizka: An very plain and boring moon at its surface. But it has an detail: Their composition is not from Yagarian system. Pizka come from another star system and got caught by Tiratas gravity. Oh, and has a good view too.

Nipi: Nipi has some tremedous deposites of Quartz, and due to this in his surface there has giant quartz crystals, the largest reaching 1200 meters in height.

Great, now that we have an solid basis, lets start.


In Ceatrus’s ocean, some complex molecules were grouping together, forming new bonds, but something happened: For the first time, one of these molecules grouped together so much that it ended up splitting into two, and theses two, instead of becoming a tangle of disorganized atoms they managed to perform the same actions that the original did.

The dawn of life begins in Ceatrus.

Vita Originalis: A simple unicellular organism that only knows how to do three things: Absorb nutrients, divide into two and die when it can no longer absorb nutrients. Its DNA structure is still very simple, but it can already undergo changes.

100 million years later, the population of Vita originalis increased exponentially, and some changes can already be noticed in its population. Some individuals have suffered slight malformations in their DNA over the centuries, the majority cannot sustain themselves, but a small portion of these manage to survive, and most surprisingly: They function better than their ancestors.

Let’s see some of these new species:

Vita Glacialis: You may already know that Ceatrus has huge polar caps. These small beings have evolved to be more resistant to cold, and have also been able to considerably slow down their metabolism when there is a shortage of nutrients.

Vita Sicarius: Why waste time looking for nutrients when there are an abundance of cells with everything we need in front of us? The Vita Sicarius’ diet is based mainly on nutrients from dead cells, either from hunger or from its predatory pilus.

Vita Persecutorum: With the emergence of the Sicarius, immense environmental pressure arose for more peaceful cells to evolve. Vita Persecutorum was the first of these, developing a stronger cell wall, and some movement flagella to escape its predators.

Vita Vindicta: Instead of fleeing, this branch of Persecutorum decided to fight back, evolving a small reservoir of toxin that was released when it felt attacked.

Vita Flavus: Instead of seeking environments in the ocean, Vita Viridis, during a period of nutrient scarcity in coastal regions, evolved to produce chlorophyll b and Xanthophyll, which gave them a yellowish color.

That’s all I’ve done so far, if you want to suggest a branch of a species I’m open to it!


The project seems great, but I have one question: How does Bhafa maintain it’s atmosphere from escaping into space? I’m rather sure that it’s a relatively small object.

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Thanks! It is due to two reasons: In fact, Bhafa is quite large, up to 4500 in radius. Secondly, it has a VERY high density, Bhafa has TWO times the gravity of Earth, and because of this the atmosphere manages to remain intact.


(Sorry for doubleposting mods, but this post wouldn’t make much sense with the previous post theme.)

650 million years later, Vita Flavus branched into several species, let’s call this genus “Flavurii”.

Flavurii Litus: They live in coastal regions, and normally live in large colonies, and nqormally don’t move much, except for the dance of the tides.

Flavurii Saxum: A branch of Litus. It has adapted to live on coastal rocks and in some seaside hailstones. The constant tide allows them to stay hydrated.

Flavurii Demergi: They adapted to living in the high seas, and had to develop a relatively strong cell wall due to an organism that we will talk about later.

Flavurii Polari: With less sunlight on these specimens, living at the cold and rarsh south pole of Ceatrus, they developed a dark orange color to absorb more sunlight.

With the emergence of these new Flavurii species across the globe, several species wasted no time and saw an opportunity for new nutrients.

Glacius Leo: During that time, the South Pole was depleting its natural nutrients, and this caused a branch of the Vita Glacialis to adapt to be able to process Flavurii Polari cells. The south pole had a higher concentration of oxygen, which species in the region had already developed resistance, which made adaptation a relatively easy process.

However, in this environment another branch emerged, The called Glaciue Ausu, who fed on the other species present in the region, and if that were the case, on themselves.

Sicariae Herbivoris: Vita Vindicta was one of the first species to feel damage caused by the increase in oxygen in the atmosphere, its population decreased drastically, and Vita Persecutorum was unable to fill the ecological niche in time. This has given rise to immense ecological pressure to adapt to a new diet, developing enzymes and defense systems over the time to become capable of processing the toxic oxygen.

Sicariae Burgaria: It was quite common for Vita sicaris, long before their diet adaptation, to eat Demergis unintentionally. Most died due to the oxygen content, but something remarkable happened in one. Instead of dying, Sicaris absorbed the photosynthesizing structures and they became part of its body and a supplement to its diet.

The sudden increase in oxygen levels in the atmosphere caused the extinction of the genus Vindictia 200 millions of years later, and the near extinction of Persecutorum, who were able to survive thanks to their innate biological resistance.

Another species that was wiped out by the oxygen catastrophe was the Glacius Ausu, however one of their descendants, which fed on cells that fell to the ocean floor, called Glacius Thassalus, were isolated enough to be not affected by the oxygen.

(Sorry for the delay, I started making drawings for the species, so its taking a while)

Fast forward 150 million years, multicellular life thrives across much of Ceatrus.

Bivoridae Primis, AKA Pickespole: A simple organism with bilateral symmetry, its rear part, in addition to providing movement, is where most of the photosynthesising cells are concentrated. During long periods without food, it floats to the surface and remains on its side, in order to absorb more sunlight.

Bulgaridae Victoria, AKA Regiafish: An organism that depends entirely on photosynthesis. Much of its surface is outside the water, absorbing sunlight. Part of Pickespole’s diet.

Regiafish has an simple lifecycle, showed in the image.
1-Proto-regia fish separates from its parent organism

2-The flagellum is removed after some time, the proto-regia inflates itself with absorved oxygen and floats to the surface.

3-The new regiafish grows over time, creating more proto-regias, restarting the cycle.
(If anyone has a question or thinks something wouldn’t be possible, let me know!)


Wait, you’re planning to developed Sentient Plants for this project or something?

Is there any reason for them not to? Planimals can be cool


may i suggest a branch of the regiafish that stays deep in the water to avoid predation by the pickespoles and as a result has become an extremely dark green both to blend in with the depths and get enough energy to survive from the sun?

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That… called fungi (but with the photosytasuis)

(me learning life Life Sciences at the university, already in the third year and starting to do a seminar this year)

Kinda… Basically everyone on this planet is going to be more or less dependent on photosynthesis (which is kind of ironic since it’s a relatively cold one)

Oooh, thats a good idea! I was having trouble thinking about regiafish branches, thanks


May I suggest other species evolving on Bhafa, and have them live and evolve in the deep oceans, with special proteins that can turn heat from hydrothermal vents into energy?

I was actually thinking about something like that, but they would be Ceatrus bacteria that were taken to Bhafa because of some meteor or something.

Also, some sneak peeks from the next part (Aka Section of unorganized conceptual arts influenced highly by Cambrian biology)


This looks cool!

Also, I’ve made a sort of concept model for Pickespole:

It’s not that good, but yeah! There it is!


Awwwwwww they looking so cuteeeeeee :smiling_face:

Very good work!

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Thanks!! It was my first-ever attempt at 3D moddling.

would a descendant of the pickespole that bites onto another animal it and starts stealing its blood and putting the blood it’s done with back and has basically become a leaf that leaves if it doesn’t like you fit into this ecosystem

Sorry, I don’t think I understood very well what you meant.

But anyway, this looks like a clade I’m working on, as you can see, the little guy in the middle has become some kind of parasite and the one on the left has decided to occupy the niche of a plant.

and yeah sorry for bad quality


Are tinier relatives of the present organisms alive? If so, a Picklespole could specialize for filter-feeding on them by changing it’s mouth.

what i meant was a species that’s like a leech with a loop digestive system that it uses to take nutrients and carbon dioxide from larger organisms and put excess glucose, excess oxygen, and waste into the host’s bloodstream without actually digesting the blood and just taking nutrients from it instead, and it has taken the bodyplan of a leaf slug mixed with a leech. that guy in the middle looks like it could do it though

I just realized, on Netarai, there already is basic life, yet we’ve only been focusing on Ceatrus.

In fact, It is not exactly life, but rather basic organic matter, as in Iapetus, Saturn’s moon.


The Pickepole population divided into three phyla:

Parvurae: Small, rapidly reproducing herbivores.

Prodigiosae: Sessile creatures, they are either parasites or plants.

Piscium: Ornivorous creatures in general.

Now that we know the important things, let’s see the species we have during the Torsian Period.

SImbiko: A small fish that feeds on the grime accumulated in larger fish. It lives in a symbiosis between these fish.

Glacifish: It adapted to live in the north pole, it has a thick membrane to help resist the cold and an elongated body for greater photosynthesis.


Ollamig and Ollamall: Both have adapted to fill the niche of sea plants/cucumbers, they stand firmly on rocks, absorbing through photosynthesis and every now and then capturing some unsuspecting small fish and devouring it.

Parasitah: (thanks willow for original idea!) This little parasite grabs into bigger animals and It digests nutrients from the host’s blood, and injects the byproducts of its heavy photosynthesis into the host’s bloodstream.


Meoowis: A large, and cute fish with two fins on top of its head, that looks like an mammal native of the third planet of a yellow dwarf. It is predominantly herbivorous, and its size makes it difficult for predators to hunt.
Besides the main meoowis species, two branches of them exist in Ceatrus:

Meoowhale: The largest animal in Ceatrus, it is 10 meters wide and its a filter feeder, its diet is based on small fish and algae. Typically found with Sinbikos on it.

Meooch: It’s native to a region where there was no medium herbivores, so it took that niche.

Canbrin: A medium-sized fish with an ornivorous diet, but with a preference for meat. It has developed some sharp horns that pierce the skin of its prey.

Fasbohi: An efficient herbivorous swimmer, it escapes its predators at a speed of 60 km/h.

Matarar: A close relative of Fasbohi, it is a deadly predator that camouflages itself among fields of algae to catch its prey when they least expect it.

Solarray: This fish spends much of its time near the surface, absorbing as much sunlight as possible. In case of predators, it attacks them with its frontal appendages.

Buzzo: This one took an extra step: It jumps out of the water and glides for a few seconds, carrying out photosynthesis without difficulty and, on top of that, it helps to escape predators.

That’s all I’ve done so far, there are still a lot of things missing like plants, regia fish, more small herbivores, Latin names, etc, but I hope you like it!