Sorry for lateness.
Organism: Polypu
Ancestor: Zeppu
Selective Pressure: Nutrient access and energy usage.
Mutation: Disappearance of lower 'body' concurrent with gas sac photosynthetic adaptations. Previously, Tonu-family creatures were forced to expend most of their energy supporting a lower photosynthetic body with a gaseous sac. Continuing trends that began with the Zeppu, the lower body atrophied further until nothing remained but a few translucent ammonia-absorption tendrils. Concurrently, a diploblastic differentiation within the gaseous sac itself occurred; ectodermic cells specialized for photosynthesis over the increased surface-area of the sac, and endodermic cells specialized for gas production. Polypus have grown in overall volume while decreasing in mass compared to the Zeppu, now looking much more like true 'bubbles'. They generally range between 0-20 meters above the ammonia sea, and some isolates are beginning to float over smaller bodies of liquid as well. They do not particularly care about predation, preferring to out-reproduce through massive spore-seeding of the sea as with previous generations. While most Polypus float alone, some members of the family have several distinct linked bubbles with internal membranes between them dissolved.