I am seeking help with the identification (at whatever lowest taxonomic resolution) of a few specimens of marine brachyuran crabs encountered among macroalgae on a tropical rocky shore. I have photos which I can send out to anyone willing to help
It is really hard to make a good job just by looking at your pictures. However, this might point you in right direction to further explore. Since you have the specimens with you, you can use a taxonomic guide. Here is what I can do so far:
A and B belongs to the family Paguridae (hermit crabs).
W an O seems to be the same species and belongs to the genus Ocypode.
X seems to belong to the family Grapsidae.
This what i can do, with what you have so far. I might be able to be a bit more helpful with closer pictures.