These guides are designed for identification “in the field” where you might be looking at live crabs by eye or through binoculars or from photographs. I will generally try to avoid characters that will require you to physically catch the crab, although I may mention a few for secondary verification. They do not include the more strict taxonomist-style characters that may only be visible under a microscope or via dissection. It is also assumed that the individuals are living, as death (and even capture) can cause dramatic color change.
These guides are a work in progress, with only about half completed at this time. The western Atlantic and eastern Pacific Realms are roughly organized from north to south, while the Indo-WestPacific Realm is roughly organized west to east (or perhaps clockwise) starting from South Africa.