system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: I live in a small town. Every time after it rains, there's a LOT of slugs on the sidewalk. Why?
gpt
The bodies of slugs-- and snails, as well-- are composed primarily of water. In addition to this, they breathe through their skin. While this is beneficial in wet environments, when its dry they're in danger of drying out and dying. This is why you won't see many slugs and snails out during the daytime-- they come out at night when it's cooler and there's more moisture in the air.

As a result, they come out during and after the rain because the air and the environment is filled with residual moisture from the rainfall, making the conditions, temporary as they may be, prime for them to be active. 

This is coincidentally why pouring salt on slugs has such a reaction-- it draws the moisture from their body and rapidly dries them up/kills them. So please don't do that, hahah.