Answer: I think it is uplifting movement theory
Explanation:
I am learning about this stuff in my class.
hope this helps
I do think that they close to not allow too much of either water or air from entering.
the hollow tube allows water to flow easily.
https://www.bbc.co.uk/bitesize/guides/z28g7p3/revision/1
60% of animal life live in oceans
