How do worms know to end up on the asphalt or sidewalk when it rains?
In: 2
Worms leave the ground when it rains because they are drowning.
Worms breath through their skin, and it’s a lot harder for them to absorb oxygen in water.
So when the ground gets soaked they burrow upwards in order to get air
It’s actually a common misconception that worms come to the surface to avoid drowning! worms can actually survive underwater for extended periods of time (days to weeks) without suffocating. In fact, they’ll suffocate if their skin gets too dry! The best guess for why worms surface during rain seems to be that when the ground is wet, they have no risk of death by drying out and so can take advantage of how much faster it is to move across the surface than through packed soil. Here’s a good article from Scientific American about it: https://www.scientificamerican.com/article/why-earthworms-surface-after-rain/
As for how they decide where to go, worms have very good senses of taste and smell, as well as being able to sense vibrations, and although they don’t have complex enough eyes to see images they can tell the difference between bright and dark areas. The worms you see on roads and sidewalks are not there “by choice”, but because those are surfaces that they aren’t able to burrow down into when the rain stops and they don’t know where to go.
Latest Answers