Evolution of life on Espa

This page is a documentation of the **Evolution of Espan life forms**. This page will not include every single one of the evolutionary creatures, for the obvious reason that ecosystems over time are insanely diverse, but will focus on giving a broad but cohesive overview.

Espa is the third planet orbiting Odjor in the Axel system, Odjor only has a luminosity of 65% that of the sun, Espa's gravity is 116% that on earth and its atmospheric pressure is over 3 times that of earth, meaning life on Espa will have to adapt to that.

Due to the stronger gravity and dense atmosphere on Espa creatures are different from Earth life, big animals can easily get airborne in the dense atmosphere.

## The building blocks

This section documents the earliest history of the planet and its lifeforms.

### Formation and Impact

The planet Espa is approximately 5.22 billion years old, formed by method of accretion the planet was able to gather a great mass early on in its existence, it is unclear when but at some point around 5.09 BYA the planet had a disastrous encounter with another planet resulting in a glancing blow that deposited iron into the planet and ejected tonnes upon tons of debris which let to the creation of a ring around the planet which in turn would accrete into it's major moons Azhban and Yattuk. Similar to earth the planets spin was greatly accelerated by this early impact and its estimated Espa immediately after the impact had days that would have been only 8 hours long. Espas newly acquired moons would have a stabilizing effect on the planets rapid rotation over the ages this rotation would come to slow to 31 hours and 35 minutes we are familiar with. Additionally the moons would introduce tides to the oceans.

Initially formed extremely close to the planet, these moons gradually moved away from Espa over the eons reducing the tidal effect and rotation speed.

### The Story begins

Around 4.95 BYA, 250 million years after its initial formation Espa was able to form the first fragments of a solid crust, due to the planets mass it took significantly longer than the earth did to cool off. While it was cooling these fragments gradually transformed into the first tectonic planets of Espa, though unlike today Espa back then had hundreds of small plates.

By this time Espa had an atmosphere of predominantly Carbon dioxide, Water Vapour and Helium as the planet began to cool the atmospheric water rained down upon the surface forming the first puddles and lakes. These early lakes were highly acidic and the first places for Espa to form its primordial soups by 4.90 BYA.

As the water rained down and the Hydrogen and Helium escaped into space, Espa retained an almost 70% Carbon dioxide atmosphere with a secondary amount of Nitrogen, Nitrogen is an geologically stable gas and as such it would gradually build up in the atmosphere over the eons.

More water arrived with the onset of the Late Heavy Bombardment of the Odjoran system 4.75 BYA, which was a 200 to 300 million year long bombardment of meteors and debris left over from the odjoran systems formation, these meteors carried Minerals, Carbon and primitive proteins from outer space, which got mixed with the already present primordial soup. It's thus not long after that Espan Abiogenisis occurs somewhere around 4.71 BYA with an Biosignature appearing in 4.68 BYA

With heavier elements such as Iron gradually sinking to the planets core a very weak magnetic field became active around 4.65 billion years ago, only about 10-20% as strong it is today. As the Late Heavy Bombardment comes to a gradual close around 4.5 BYA it marks the end of the Plutonian Eon and the start of the Katagogian Eon (named after the Greek word for origin).

The Espan LUCA lived at around 4.4 BYA.

### The first lifeforms

Life on Espa started out being anaerobic. Because of the thick atmosphere it did not develop much photosynthesis in these early stages, instead starting out as heterotrophic, incapable of producing their own food so instead the searched for food in their environment.

However at some point very soon after life first appeared some organisms evolved to use inorganic molecules to power chemical progresses from which they derive their energy, thus becoming autotrophic, able to produce their own food.

Early autotropic bacteria diversified into phototrophes (photosynthethic) and chemotrophes (chemosynthethic), whereas photosynthethic organisms use sunlight to power themselves, the chemotrophes use H2S to power themselves.

sunlight photosynthesis of phototrophes:
6**CO**2 + 6**H**2**O** → **C**6**H**12**O**6 + 6**O**2
hydrogen sulfide chemosynthesis of chemotrophes:
12**H**2**S** + 6**CO**2 → **C**6**H**12**O**6 + 6**H**2**O** + 12**S**
Additionally H2S dissolves in water making the oceans acidic meaning these early lifeforms had some means to tolerate the acid.

## The March of Life

As these early bacteria proliferated they started changing the composition of the atmosphere, with the phototrophes releasing **O2** and the chemotrophes releasing **S2** into the oceans.

As the oceans begin to accumulate Oxygen and Sulphur rusting becomes possible leaving vast iron deposits at the ocean floor as well as further acidifying the oceans. Additionally the atmospheric Sulphur dioxide concentrations dropped steadily.

Slowly but steadily the oceans fill up with oxygen until the point of saturation is reached by around 3.5 BYA the oceans have completely saturated with oxygen which means its now being released into the atmosphere. By 2.9 BYA the oxygen levels reached 0.3% by volume passing the Pasteur point above which facultative aerobic microorganisms and facultative anaerobes adapt from fermentation to aerobic respiration. By doing so a tipping point is reached in evolution.

### Oxygen Catastrophe

This sudden appearance of atmospheric oxygen meant it could be utilized for aerobic respiration which works far more efficiently above the Pasteur point. The extreme benefits aerobic organisms now had over anaerobic microorganisms had dire results, oxygen was a poison to anaerobic life leading all the non-chemosynthetic anaerobic life to die out in the first mass extinction during which 99% of Espan lifeforms died out. This event marked the end of the Katagogian Eon and the start of the Anapnoian Eon (named after the Greek word for breathing).

Additionally to the oxygenation the higher oxygen levels have other effects on the planet, firstly the oxygen combined with Iron to start a new global phase of rusting, turning the Espan oceans brown red, but fore-mostly dropping the methane levels - The oxygen combined with the methane to form carbon dioxide and water, which do not retain heat as well as methane does - sending Espa deep into a vast ice age called the Kokkinoan Ice Age. For the planets climate to adapt to the new atmosphere 400 ma had to pass, and only by 2.5 BYA the ice began to retreat.

### More Complex Cells

In the new oxygen atmosphere aerobic lifeforms soon developed into complex colonial and eventually multi-cellular lifeforms, drastically speeding up the process of evolution.

While this was happening somewhere around 2.1 BYA the first bacterial viruses appear. Followed at around 2.0 BYA by the evolution of sexual reproduction. At about 1.91 BYA the first bacteria with a nuclei form thus separating the main domains of prokaryotic and Xenokaryotic Cells on Espa.

 File:Xenokaryotic Cell.png
At around 1.84 BYA an aerobic protist enters the system of a larger protist and avoids digestion, becoming a source of energy instead. Eventually it becomes just another organelle inside the larger protist causing mitochondrial symbiosis. These symbiosis's happen again for phototrophes at 1.56 BYA, where a Photosynthetic Autotrophes became integrated into a larger Xenokaryota making the basis for all plants and algae. Resulting in the evolution of sexual reproduction opposed to Asexual reproduction by 1.5 BYA.

Its also around 1.5 BYA ago that Espa's solid inner core forms rapidly boosting the magnetic field of the planet.

## Multi cellulars

Up to this moment living cells that had been produced by cell division simply drifted away from each other. But now with the aid of increased oxygen levels some cells stuck together, some of these clumps of cells would eventually evolve into the first animals.

There were many advantages to being multicelled, colonies of cells could collect more food, control their internal environment and act efficiently by working as a team.

### The first Multi-cellulars

By 900 MYA Espa wass entering a period of increased dynamics called the Omádian Period, the multi cellular clumps were evolving, the first clumps of cells evolved to be sponge like creatures in various shapes, on a rudimentary level there is no simpler body plan than that of a sponge, they don't have any organs or digestive tract, they are just a clumb of cells which stick together to filter nutrients out of seawater.

One of the first creatures to be identified was Fteró Archaía. Since it was a sessile life form, it needed to have a surface as a means of capturing food particles, according to the Square–cube law this favours a tall feather like structure. These creatures showed alot of diversity mainly centered around the feather-shaped designs and are commonly grouped as Fteromorphs.

These early multi cellulars still faced a critical handicap, they were sessile meaning they couldn't move around.

An evolutionary breakthrough was reached when the first motile animals such as Mchidia evolved, even though these creatures were still very primitive. The first motile animals were very slow, they crept along the seafloor moving from one feeding spot to the next absorbing the organic matter beneath them and then moving on to the next place.

Motile animals had an tremendous advantage over sessile animals, they could move away from danger, move towards a more richer food source and they could leave a spot overcrowded by their neighbours.

With movement unlocked the first species were able to unlock predation and change the game forever. With the appearance of the first predators creatures had to develop new means of defense and an evolutionary arms race would ensue between predator and prey and be the driving force behind the evolutionary progress of Espa.

## The Vavilobian Explosion

842 MYA the Omádian Period was superseded by the Vavilobian Period (named after the Georgian word for blossoming), a massive bio-diversification event in the ancient Espan oceans triggered by the first appearance of predation.