Era 4 - The Killusian Era
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The climate continued to cool during this era, leaving many life forms confined to narrow strips of the equator and increasing the pressure of competition. Thick ice sheets regularly formed at the poles during the global winter. The most nutrient-rich waters were often too cold for complex life forms to survive, leaving vast blooms of plankton to go untouched...
The
Kolonia was one life form that adopted a boom-and-bust strategy, making the most of the global summer season to reproduce in as great a volume as possible. Evolved from the
Cruizer lineage of simple, tubular, free-swimming filter-feeders, the Kolonia was able to alternate between free-swimming and colonial life stages, the latter consisting of large chains of connected individuals. Though lacking a true circulation system, the colonies were able to share nutrients to a certain extent, growing rapidly at either end when enough plankton was around. At times the Kolonia could bloom in vast numbers, however these blooms were inevitably short-lived.
Other life forms took a slow and steady approach; the
Nolock was a new branch of
Sponger that evolved starchy energy stores, built up in good times, for use in times of duress. Although the Nolock was not especially adapted to cold water, it could use its energy reserves to help survive the winter months in more marginal areas than most other life forms.
Another interesting branch of Sponger appeared at this time - the
Magitapeti discarded the porous mineral skeleton scaffolding that served its ancestors so well, and instead evolved sealed gas-filled chambers that enabled them to freely float above the seabed. Magitapeti are also remarkable for the sizes to which they grew - in columns up to a couple of metres long, which was especially large considering their otherwise very primitive nature. As a defensive measure, this was effective against being swallowed whole, but not against being eaten alive by the
Nusance - a new predator that simply coated its prey in digestive fluid. Predation and competition eventually forced the Magitapeti into extinction.
The
Syphidae family continued to evolve rapidly, and these species were among the most successful; their muscular bodies combined with a basic nervous system proved to be a key advantage, enabling bursts of speed and better-coordinated movements. These animals survived as filter feeders when small, and predators of other animals when large;
Oculisyphus remained fairly common, especially in bright sunlit waters, while the blind tentacle-armed
Agarose line gave rise to the
Nusance and
Manipose...
Nusance was a messy eater, initially digesting its prey outside of the main body cavity, while wrapping it in stinging tentacles - which were deadly against the unprotected skin of its prey. While this was somewhat costly, and not very efficient, it did allow the Nusance to target creatures larger than itself, even to feed on the
Thingus and its descendents which had ruled the seabed for so long - leaving half-digested bodies in its wake.
While Nusance became top of the food chain, the
Manipose was also successful thanks to its grasping/tearing appendages and its improved digestive tract (the most complex yet). Being altogether more elegant than its cousin, it was efficient at eating some of the sea algaeforms as well as catching small animals. And despite the lack of eyesight, the basic scent organs inherited from the Agarose still allowed both these predators to track food sources over longer distances, or to narrow in on food on the murky seabed.
In the face of these threats, and an ever-increasing array of sessile, drifting and swimming filter-feeders competing over what remained of the warm-water ocean, the
Superhydrus family proved simply too over-engineered to survive. In one last flourish the
Moderamenus evolved touch-sensitive ‘paddles’ and intricate limb structures, but this brought only minor feeding benefits at the expense of slower growth rates, and with no real defence against predators...
One branch of Superhydrus did survive this era, but it was really something of a degenerate compared to its cousins: the
Maceria, which had become a largely sessile creature with only one feeding ‘arm’, surrounded by a phalanx of spikes for defence. The Maceria did however introduce a form of sexual reproduction - one of the first complex organisms to do so - with its ‘arm’ serving the dual purpose of launching sperm and egg cells into the water at regular intervals. Thus the reduced population was able to maintain a healthy amount of genetic diversity.
The closely-related
Aarmulous line proved more successful than the Superhydrus, leading to the
Tarmulous, equipped with primitive head-mounted ‘fins’ and proto-eyes, it had at least a small chance of avoiding danger. Though, internally this lineage remained primitive, lacking a true nervous system as seen in the
Syphidae which hunted them, this did make it easier for these animals to clone themselves and survive through weight of numbers.
While no animal had yet adapted to cold water, some were able to adapt to be resistant to the fungus-like
Toxofilamenta blooms, and thus were able to expand into new territory and new food sources; first the
Mortovivium, an evolution of the mud-eating
Rovster with tooth-like structures attached to its ‘head’, enabling it to slowly attack the hardened
Splonts which already coexisted with Toxofilamenta, as well as scrape away algae and bacteria from seafloor rocks.
Secondly, the
Eccentringus, a branch of the formidable
Thingus family, which could similarly smother and digest smaller Splonts as well as Toxofilamenta. As a side effect, Eccentringus could often absorb the toxins for its own benefit, serving as a deterrent against
Nusance attack. Eccentringus is also noteworthy as being another branch of life to adopt a form of sexual reproduction, in this case with two distinct genders - there was not much romance involved, as these creatures lacked a nervous system or much in the way of senses, and simply indulged in mass spawning (adding more food for filter-feeders), but it was enough for Eccentringus to become the most successful of the
Thingae.
A side effect of all this was to make Toxofilamenta blooms very short-lived in warm waters where these animals lived. This also reduced the
Splont’s advantages of toxin resistance.
Wryglus was able to take advantage and grab a greater share of the seabed; like its ancestor the
Spinster, it built tubes of compacted sand, gravel and resin within which to hide, but the Wryglus added a touch-sensitive ‘head’ with extendible, plankton-snatching tentacles, reducing the exposure to the main body when feeding. It was a simple but very effective combination, and fossils of this time show that Wryglus was one of the clear winners in the competition for living space in the equatorial shallows, often forming dense colonies of tubes on the sea floor where once had been only slow-growing Splont reefs.
Meanwhile another branch of the Thingus arose - the
Dingalingus was a cousin and rival of the Eccentringus; staying clear of Toxofilamentus blooms, it gained a set of basic eye-spots to help navigate to sunlit areas over the increasingly-complex sea floor - though without a nervous system, it wasn’t able to avoid harmful animals such as the stinging
Nusance (not that any member of the Thingus family could move especially fast anyway). Dingalingus did however evolve some biochemical tricks that allowed it to maintain its captured chloroplasts for longer periods, reducing the need to feed on fresh algae. Although not as dominant as its ancestors had been, Dingalingus remained fairly common in the equatorial shallows.
Toxofilamenta and
Filamenta still flourished in cold waters and deep reaches where no animals went, particularly around deep sea vents which were rich in bacteria and minerals.
There was very little diversification among ‘plants’ during this era. The
’Drinkipoo’ was the only new branch to appear - making use of the adhesive strands which held it together, the Drinkipoo turned them into traps for small animals, which were then slowly digested by its secretions and absorbed. This was a valuable source of nourishment in expanses of warm-water ocean otherwise lacking in nutrients, but otherwise the added complexity and was not an advantage over its cousins.
Hyphomorph continued to grow in peace among the inland lakes waterways, usually remaining ice-free all year and fertilised with eroded minerals, where they lived alongside the
Asymenta (a relative of Filamenta) as the only other complex life-form. Aside from
Kalus colonisation of the high tide line along the sea shore, the rest of dry land remained devoid of anything but smudges of microbial life.
Otherwise, most algaeforms - like animals as a whole - showed a continued decline in numbers as they were unable to survive in the cold water that now made up most of the ocean. But there was one big exception;
Killus was able to thrive in huge numbers, forming vast, tranquil carpets beneath the waves. Having already appeared two eras previously, it remained the only algaeform adapted to survive in cold water, and could now grow almost unchecked in temperate and polar shallows, where it could also take advantage of nutrient-rich currents, and free from attack by any animal. Its starchy, energy-storying body also helped to see it through the global winter. Killus still faced attack from aggressive
Toxofilamenta blooms, but these were only a real problem when populations grew too dense in the first place.
With increasing amounts of carbon being absorbed by the Killus blooms, over millions of years, carbon dioxide continued to filter out of the planet’s atmosphere. The cold spell showed no signs of easing as this era drew to a close, and the ancient tropical habitats continued to be put under pressure...
Tree of Life:
Planet Map:
Stats:
*Species Stats can be found here*
*New* Diversity bonus:
(this is a function of age, population, lack of previous branching, and method of reproduction)
The following ‘species’ have become diverse enough that any new evolutions from them can have
three new traits instead of two…:
* Toxofilamenta
* Eccentricus
* Chalidus
* Killus
Notes:
Apologies this update has been in ‘development hell’: deciding what to about the world map / redrawing the tree of life, re-writing parts where I wrote too much… while recovering from illness, being exhausted from work, deciding to quit my job, and now being gripped by anxiety and wanting to backtrack (I’ll have *that* discussion with my boss tomorrow), starting at the gym after a long absence, and finally catching up with my friends / networking this weekend after an antisocial month (three nights of socialising in a row followed by sleeping til 4:45pm local time today), you could actually say its a wonder I got anything done at all
I do hope to up the pace for the next update...
@TheGentlemanSpy, I'd envisioned your evolution as being a new branch from the base Sponger (as per your submission) though I later realised you most likely wanted to branch from the Splont. Apologies for that.