Hycean

Hycean hycean, a remarkable flying predator named for planets that mix a hydrogen sky and a water ocean.

1. Gasbag flyer Though descended from the same squidlike ancestor as the houndgar and other Protean teuthis, the hycean's mantle is full of buoyant hydrogen. The ancestral hycean probably stored ammonia for buoyancy, like many Earth squid. The hycean uses bacterial symbiotes to convert this ammonia into carbon nitride, which, when exposed to sunlight, splits seawater into oxygen and hydrogen lifting gas.

2. Predatory fisher Free of most predators, the hycean drifts above the sea surface and snags prey with its arms. The larger a hycean's gasbag, the more food it can afford to lift and digest. Large prey can be suffocated by holding them clear of the water until their gills dry out. The sails provide steerage in the wind, and can be flapped for emergency power.

3. Flammability risk Any spark may ignite the hycean's gas bag, with disastrous results. Hyceans are acutely sensitive to electromagnetic activity, and may be forced to shelter in the water during thunderstorms.

4. Philosophical musings The buena vista hypothesis (proposed by Malcolm McIver) argues that advanced cognition could only evolve when Earth fish began to raise their eyes above water, allowing them to see far enough to require long-range behavioral planning. If this hypothesis is credited, then the hycean — as one of the only discovered Protean species that lives outside water — may be unusually intelligent.

Recommendation: avoid areas beneath hyceans. Monitor for signs of high-level behavior, such as 'fertilizing' certain areas of the ocean with defecated waste.