In the past research has concluded that sea creatures like Lobster can’t feel pain. New research from another group of scientists, including Robert Elwood, suggests that crustaceans may in fact feel pain. However, it might not be the same sort of pain that humans feel.
The team says that testing pain response is difficult in part because pain is difficult to define. The scientists say that when an animal responds to something that a human would consider painful, it doesn't mean that the animal is in pain. The response could be a reflex reaction. In a reflex signals don’t travel all the way to the brain and bypass the part of the nervous system that perceives pain.
The researcher started using prawns in tests and coated the antennae with an acetic acid solution. He found that the prawns would begin grooming the antenna with complex and prolonged movements after the acid solution was applied with movements of both front legs. He also noted that the grooming diminished when a local anesthetic was applied before the acid solution was used on the prawns.
He says that this prolonged and complex grooming behavior indicates a central nervous system in the prawn. He also tested a similar theory with Shore crabs. These crabs hide during the day and were put in a habitat with different shelters to use. Some of the shelters were able to apply electric shocks to the crabs and force them out during day. The researcher found that the crabs that were shocked were more likely to change their habitat in the future.
That implies rapid learning according to the scientists such as you would expect to see when the animal is in pain. The results of the tests aren’t exactly concrete proof that crustaceans feel pain, but the researchers say that the findings were enough that they will change how they treat and handle specimens in their laps and urge others to do the same.