It always amazes me to find out that there are people in the world (still) who think animals do not feel pain, or have consciousness, or have emotions. I mean, seriously: all you have to do is live with an animal for any period of time to realize all animals have the same basic traits as the human animal.
One big difference is self-awareness (essentially, see your image in a mirror and know it is you). Higher animals have this (humans, apes, and I think I even read of a dolphin). Just because they don't have self-awareness does not mean they do not have language, bond with others of their kind (or even other animals) or, of course, feel pain.
So, here is another one of those articles -- this one saying that hermit crabs feel pain AND remember it. And this is news, how exactly?
Anyway, the photograph is of my crabitat at home with the three hermit crabs I have. They have switched shells a little since this pic was taken, but they are the same three. I have had the biggest one for five years, the medium one for four and the little one for three. Aren't they cute?