system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: Why do worms always congregate on the sidewalk after it rains?
gpt
Worms can't stay above ground long on dry days, they'd dehydrate and die.

When it rains they take that opportunity to try and cover a long (for a worm) distance to try and find some better dirt.

Some of them end up on the sidewalk and get disoriented, they're not well adapted to an environment where they can't just burrow back down.

The old claim that they come up to breathe isn't true, worms can survive fully submerged for a long time.