Pain in crustaceans

Pain in crustaceans is the debate of whether or not crustaceans can feel pain, and in what way they feel pain. Pain is a complex state, and it may involve suffering. It is difficult to see if an animal feels pain. In general, pain is caused by harmful stimuli, and animals that feel pain will avoid these stimuli. To actually feel the pain, the animal also needs a more or less complex nervous system. Crustaceans fulfil several criteria. They do have a complex nervous system, they have opioid receptors, and they react less, when they are given anesthetics (painkillers).

Also, they show some degree of learning how to avoid the bad stimulus.