Charybdis

Splitting from its ancestor, the charybdis furthered its metamorphic cycle due to various genetic mutations. This ultimately led to several stages evolving that did not come into direct competition with one another, which in turn allowed the population to explode.

The original form, the primary adult stage, is a filter-feeder that lives in midwater column, feeding on the various microbes that live there along with the plentiful detritus, though they will also enter the salt-water marshes or the waters off the global glaciers in search of food. They reach eight cm in length, and typically form small schools of 15-20 individuals. They have evolved a pair of side fins that undulate in unison to propel it forward. It has also evolved a complete, though simple, digestive system ending in a tube-like orifice on its underside. It is here that they also release deoxygenated water that they breath in through their mouth as well as its young. Asexual, it produces clouds of spores every few weeks.

The second stage, the spore one, consists of microscopic young floating near the surface in the thousands. They hatch rather quickly, typically in masse, and usually during twilight hours. This trait evolved to give them the best chance to avoid predators as nocturnal species are just waking up while diurnal are preparing to sleep.

The third stage, the primary larval one, consists of tiny unicellular organisms with fins similar to the primary adults. Filter-feeders, they feed on tiny microbes and free-floating detritus. Forming a part of the plankton layer, they fill out the role of the "zooplankton". They possess a more typical body plan of their ancestor the foi, though there are differences such as a trio of chemical-sensing barbels that have hardened tips for defense against predators that attempt to eat them whole. When ready, they form a cocoon on the sea floor, in which they undergo a process of rapid mitosis, forming several larva of the next stage.

As soon as the cocoon opens up, it releases several foi-like primary larva that are half a cm long. While they do resemble foi superficially, they are in fact multicellular and will eventually grow to be two cm long. Possessing a chiton-based "helmet" and barb-tipped barbels on its back, it can role into a ball if threatened. They typically feed on detritus or scavenge the dead, and possess a gland in their lower underbelly which produces a sticky enzyme that can keep them in place. They then form a cocoon themselves and will then turn into their sexual secondary adult stage.

Based on water temperature, the primary larva will become either a sessile filter-feeding female nearly six cm in diameter or a one cm long male incapable of feeding. The males seek out the chemical signals of the females, and once they find them as they use up their energy reserves, they parasitize and eventually fuse with them. At this point they produce a root like structure that digs into the female and penetrates its gonads. Once he impregnates her, she will produce his and the fertilized eggs of her other mates at constant intervals. These eggs will be carried away by the current before eventually settling down and hatching.

After the eggs hatch, the secondary larval stage comes into being, consisting of small cm long organisms that appear to be little more than swimming mouths. Blind, they filter-feed on the microbes that live near the bottom. Once they reach three cm in length, they will form a pupa and prepare for their next and ultimately final stage of life. After two to three weeks, they morph into the primary adult stage and begin the cycle all over again.