The hydrogen jellysquid evolved to escape the feathered beakworms. The air balloons of its ancestor became larger and filled with hydrogen, which lifts the body of the jellysquid right out of the water, leaving only its four long tentacles dangling into the water below. It has developed a hard, beak-like ridge around its mouth, which makes it more efficient at eating beakworms. It also has two small, vestigial tentacles below its mouth which it uses to help direct food into its mouth. Because it can no-longer use its gills to respire, it has developed a primitive lung from the major jet that remained from the filtersquid. It also has two smaller jets on either side of its mouth that it uses to squirt a paralysis-inducing toxin at predators should it feel threatened. Unfortunately, it has no eyes, so it doesn't always shoot the toxin in the right direction.
Hydrogen jellysquid reproduce in a unique way. The species has two sexes, one is a hermaphrodite and the other acts as a kind of living womb. When two of the "breeders" meet each other, they will fertilize each others eggs. They will then drift around until the come into contact with a "carrier". They will pass on the fertilized eggs into a pouch on the underside of the "carrier" where they will complete their development. Each brood consists of four to seven large, hard-shelled eggs, which when laid will float on the surface of the water for a few hours before they hatch.