Just a comment: The crab has to maintain an ideal salt level, but if the water going in to the crab doesn't have the same level, what can the crab do to keep the salt balance?
a) The crab can adjust its osmoregulation mechanisms to maintain salt balance.
b) The crab can seek out areas with water of the desired salt level.
c) The crab can excrete excess salts through specialized glands.
d) The crab can adapt its behavior to minimize exposure to unsuitable water conditions.
