Mellanta
Rather than drawing in water into its body to eat whatever is contained within, the Mellanta everts its stomach to catch food outside its body. The stomach is reinforced with collagenous ribbing, and the pattern of creases and reinforcement brings to mind a honey dipper.
It lost flexibility for its lips. Its lips are now part of a mouth-rim system that allows it to evert its stomach and keep it outside its body almost indefinitely. The rim of its mouth gets thicker and more cartilage-like with age: older specimens have a few mineralized specks of strontianite (a form of aragonite).
As the Mellanta lives in an environment with more predators, it has needed more defenses. Its tail is longer and stronger. While its ancestor rapidly "jumped" upward when attacked, the Mellanta can keep going for up to 15 seconds. It cannot move horizontally, and can barely move diagonally. Much of the time, it stays nearly immobile in the water column, using the disc-shaped, air-filled pockets in its body to control buoyancy. Older specimens, which are bigger and have a mouth-rims reinforced with strontianite specks, may rarely twitch their tails to maintain buoyancy.
The two-pointed fins are stiffer than before, and reinforced with thick, cartilage-like strings of gristle. When grabbed, bitten or engulfed, it rapidly flings its fins outward, making it harder to swallow or grip. The fins are of little use in swimming, and are collapsed when moving rapidly upwards.
Mellantas’ vision is poor: they can detect light and dark, and blobs of green, blue, yellow and red. (It has lost its other colors.) At twilight, it ascends upward to the sunlight zone, and descends once again by sunrise.
It can regenerate any part of its body (usually its fins or tail) but its lights and stomach. Indeed, any big injury to its stomach is fatal, rendering it unable to eat as it slowly digests itself.
Its prolific reproduction and quick maturation rate make it one of the most abundant organisms in its habitat. Although they are not gregarious by nature, they often occur in glowing “swarms” due to fortuitous currents or feeding opportunities.
The Mellanta digests food using Ribbon-Tailed Detritis, which swim through its stomach mucus and swarm, piranha-like, on any trapped or dying microbes caught in its mucus.