Polentling
The Polentling's life is something between a hagfish and a deep-sea leech: It feeds on living hosts and scavenges.
Its larvae are simple, microscopic, globe-shaped consumers of debris and microbes, with no lights and little swimming ability. Later on, they metamorphose into a scavenging and parasitic form.
The Polentling's mucus patches have duplicated, increasing its production of distasteful mucus that makes its body more hydrodynamic. Though it can produce light, most of the time its lights are turned off. The Polentling has lost most of its light-producing spots and has also lost the ability to produce several colors. Its upper and lower fins are small and largely fatty flanges. The Polentling mostly moves through trout-like subcarangiform movements, and its side fins are fairly thin. Mostly, the side fins are spread out to lodge itself inside the gill passages of its prey if the prey struggles.
It navigates primarily through a sense of smell/taste as chemicals enter its nasal patch (a digestive membrane at its anterior end), turning on its red lights as it gets closer. As red light does not travel far in the water, it can reduce the likelihood predators will spot it, if they can detect red light at all. When very close to its food, it detects the movement of water currents using a wavy lateral line just below its upper mucus patches.
When attacked, it flashes its blue lights, potentially attracting big predators to eat whatever attacked it.
Diet
Unlike its ancestor, which detected Carpotesta Devoratori descendants and swam away, the Polentling automatically swims towards various Geletaventrians. It slips its anterior end or even part of its body inside the gills or gill openings of the organisms. Once inside, the Polentling presses its nasal patch to the gills or the lining of the gill passage and secretes enzymes, dissolving tissues. Four sticky bumps on its subtly ribbed nasal patch give it a better grip and increase the surface area it can secrete enzymes.
More rarely, the Polentling feeds on the blood in host wounds, such as the wounds Devorators might gain after a fight for territory. Its enzymes can reopen congealed spots or partially healed wounds.
The Polentling also scavenges: It wriggles into the dead body through the gill openings and feeds on the gills and gill passages first, if not eaten already. The Polentling will even enter a dying Geletaventrian, eating it alive. As it feeds, it secretes a distasteful mucus with compounds similar to corn polenta. This makes the body much less tasty to scavenging species of Geletaventrians, which otherwise might take a bite out of the Polentling itself while feasting on the corpse.
Though the Spectrestar's habit of cutting out chunks of flesh from Geletaventrians gives it more wounds to feed on, it also competes with the Spectrestar in some habitats. They both feed on dead bodies, and the Spectrestar isn't as deterred by the Polentling's distasteful mucus contamination as Geletaventrians.
It spends much of its time immobile in the water, twitching occasionally. Its sluggish metabolism, sporadic movement, and low food needs mean it can survive for months between feedings. When well-fed, it reproduces prolifically.