Here's a reminder on the Ancient Oculus creature and some evolution information (how it eventually evolved into the Agnoculus and Gillra creatures):
BASIC INFORMATIONThe Oculus is one of the oldest known descendants of the Agnoculus and several other sapient species on Epun. It represents the foundation of the
plutelium ("Many Arms") taxonomic clade, and many species on Epun can trace back their evolutionary ancestry back to this creature. Due to this fact, it was deemed important by Agnoculus scientists in the Genetic Age to gain a more fundamental and profound understanding of this creature.
Classification and Nomenclature: The Oculus is, as stated in the introduction, the foundation of the plutelium (which means "many arms", designating its many tentacles) clade on Epun. Its scientific name is therefore simply Plutelium Primoris (or, "the first plutelium"). It is more commonly called the "Oculus" by its more modern descendants (the Agnoculus) because they believe that the Oculus was simply a non-sentient version of themselves. Some modern Agnoculus geneticists even held the Oculi with a certain religious respect, as a kind of primitive creator-like figure.
Size: They have a very variable size, adults range from 5 centimeter to 30 centimeter tentacle-spans (or "diameter" of the Oculus if all of its tentacles are fully extended). The central eye ranges from 2 to 4 centimeters in radius, and so does not vary much between individuals.
Lifespan: Most live between 1 and 8 human months.
Anatomy: The Oculus are simple creatures, moving around using their tentacles to swim, feeding through four filter-mouths positioned on their most prominent tentacles (these filter mouths enable it to catch plankton as it floats by or slowly absorb nutrients from Epun jellyfish or other larger organisms). One of their most important characteristics, of course, is their single eye, which is relatively simple and only allows for a small range of visibility. It is quite large because it enables the Oculus to see in the very dark environment of the deep-sea trenches and habitats, but they are colour-blind and cannot percieve depth like their land-dwelling descendants. Another interesting characteristic is that unlike most tentacle'd creatures, the Oculus does not have completely shapeless tentacles: They are strengthened by a kind of endoskeleton which is in fact a system of "macrotubules", much like the microtubules in individual cells.
Reproduction: The Oculus have a simple reproductive process: After they reach maturity (in about one human week), they begin directly releasing spores and eggs into the water every few weeks or so, at periodic intervals. The male spore and female eggs meet and the young grow quickly. Since they are usually far from their parents by the time they have grown, they have to fend for themselves, explaining the low survival rate of offspring: for every thousand or so female eggs released (the typical periodic amount for an average Oculus) only about half of these will become fertilized, and of this half, only 1 or 2% will survive to sexual maturity. This periodic cycle of reproduction continues indefinitely, until the individual dies.
EVOLUTIONThe Oculus was a very effective creature survival-wise. It was already one of the largest creatures under the water at the time it was developing. Its filter-mouths enabled it to feed both off meat (if you'd call small shrimp-like creatures with chitin exoskeletons "meat"), or, if food was scarce, filter plankton out of the water. It's many tentacles gave it great flexibility and agility underwater, as well as a higher-than-average strength thanks to the strong macro-filaments in each tentacle. Looking at all this now, we can easily understand how this creature evolved into the two main sapient species on the planet, it was already the most developed organism around in post-primeval-soup times! As depicted in the picture, we see how the Oculus eventually evolved into both the Gillra and Agnoculus creatures by branching off on two evolutionary routes:
The Agnoculus: To eventually become the modern Agnoculus creature, the Oculus had to go through several separate stages of evolution. In the picture, we see how at first it developed into a more amphibian-like creature like a terran frog. At this point, the tentacles were beginning to form into functional limbs a new, stronger endoskeleton developing from the initial system of macro-filaments. It is also at this point that the claws filled with sensory tentacles began evolving and the filter-mouth developed into a tooth-lined opening. Then, when this organism finally moved onto land, the 5 limbs were already fully developed, and all that was left was for the Agnoculus to evolve its long neck and various other minor evolutionary changes.
The Gillra:The Gillra, an underwater-living creature, also evolved from the ancient Oculus. In this case, the Oculus initially had to mutate into a more fish-like creature: its tentacles changed into flipper-like limbs to speed itself up, it developed a jaw, and it started using actual gills to breathe. At this stage, this organism also developed a short sucker-covered tail with a poisonous dart end for defense against predators. In the second stage of this particular branch of the Oculus's evolution, the flippers became real paddle-limbs, the tail became more developed (although the poisonous dart began receding), and, most importantly, what had initially been two simple sensory tentacles on the creature's head became fully-functional branching tentacles for manipulating objects and tools with better precision.