Simple equations that describe fox and rabbit cycles have been turned to bacteria on distant exoplanets, like K2-18 b. These worlds hold deep oceans under thick hydrogen skies. Like duckweed on a pond, light-eating microbes cover the sunlit water surface, stealing light from those below.

Researchers simulated an ocean column with five bacterial species. Without viruses, phototrophs monopolize resources — much like an algal bloom turning a lake green. But on planets locked in endless day (one side always facing the star), there are no day-night cycles. Populations stay stable, never surging, though smaller overall.

And here’s the twist: these bacteria might feed not only on light but also on the hydrogen enveloping the planet — a far more abundant fuel.