So I was thinking of a scifi setting where life evolves on a planet orbiting a star that periodically (every couple decades) hits the planet with a hemisphere-sterilizing CME.

So the plants respond by going for the "fire ecology" strategy where they stick a bunch of hardy spores under the soil deep enough to survive it, and sprout in the wake of the surface getting blasted.

but animals can't do that, and they can't afford to stick in one location, either. No matter where on the planet your species lives, eventually you'll get unlucky and your hemisphere is the one that gets wiped.