In my zoology class we're learning about the different types of worms and stuff. The other day my teacher showed us a video that claimed scientists didn't have a real answer about why they surface when it rains. The video claimed it could be from a few reasons, not being able to breathe, vibrations in the soil, easier transportation, or for mating.
What it didn't mention and when I couldn't find from one simple google search was if they surface because of the soil compacting. On the Iowa state university website it says that "When soil moisture is at or exceeds field capacity, there is an increased potential for soil compaction, particularly at topsoil depths" So I was wondering if there has been any research done on the idea? Does soil even compact enough to affect the average worm?
(I'm just a student who doesn't know much about worms, sorry if this question is silly or obvious. Also this is one of my first reddit posts.)