Crabs will take aspirin to relieve pain

Anyone who’s ever felt a twinge of disquiet when they selected a lobster and watched it being dropped into a pan of boiling water should perhaps trust their instincts: because scientists have discovered crustaceans do appear to perceive pain. Eleftherios Kasiouras from the University of Gothenburg has found that crabs dabbed on their sensitive parts with strong vinegar will administer aspirin in the aftermath to ease the discomfort, suggesting they really are feeling pain…

Eleftherios - There are some criteria that need to be fulfilled so we're certain, and we can say beyond reasonable doubt, that crustaceans, they experience pain.

Chris - Pain is a difficult one though, isn't it? Because it's a perception. I can define pain, I can say I'm experiencing pain and you'll know exactly what I'm talking about. But how do we know that other animals share that visceral experience or whether it's just an automatic reflex for them and they don't experience the same emotional effect that we do?

Eleftherios - So we worked on shore crabs and we used different stimuli on the soft tissues of the body, like the legs, the claws, eyes and antenna, which are the little pointy things. We stimulated with acidic acid, vinegar, and it's painful to these animals, and we also used mechanical pressure to see how they responded to that. From these two different stimuli and the responses that we got in the nervous system, we could see that the signal transfers through the body to the brain and a response arises and we record these responses.

Chris - So you can demonstrate that they have the neurological capacity to detect a stimulus that we would regard as painful, and it changes brain activity when you put that stimulus into the nervous system. So you're two thirds of the way to showing that they are experiencing pain, how do we then clinch it to get the final tick in the box that this is then registering in their brain as an unpleasant thing in a way that we would say, well, that looks like they're feeling pain.

Eleftherios - We want to inflict pain on them and see how their behaviour will change and then, if we provide drugs such as analgesics, aspirin, if they would prefer the aspirin than the pain stimulus, or they want to go to the aspirin to relieve themselves from pain, that behaviour will tell us that they actually want to avoid the stimulus no matter what so they don't experience that. That's the last step of my PhD to see how the behaviour and learning come into play. That has not been answered yet, but I'm working on that.

Chris - So crabs can take aspirin. Really?

Eleftherios - Yeah. So far we've tried it on lobsters and it seemed to work okay. But more to come about that in the next paper that I'm trying to publish.

Chris - Summarising then, you stimulate them with something we would regard as painful. They flinch effectively. It's like me touching a hot plate. You can then show that they will actively seek out pain relief off the back of that with things like aspirin, which would suggest that it's an ongoing discomfort for them and they're alleviating it.

Eleftherios - Exactly. That's the next step for my experiments.

Chris - Well, what are the implications of this then? Because we traditionally just get crustaceans like crabs and we dump them in pots of boiling water to cook them. Does this mean that we ought to be rethinking this?

Eleftherios - I think so too. The industry also needs to rethink that as we do as scientists when we use them in the lab. Firstly, it's important to find methods to kill them as fast as possible. Then, for distribution we should probably be transporting dead crustaceans and not alive ones. If they're alive, the restaurants or the people that want to kill them should use methods to kill them fast when we catch them. They should be dead when we buy them from the shops.

Chris - What's a good way to do that then? Not that there's a good way to kill anything, but when it's a necessity, is cold temperature, do you think, possibly putting them in the freezer to drop the temperature down so they effectively become hypothermic and unconscious, is that the best way?

Eleftherios - We tried ice slurry because we're on the verge of finding the best method and we're conducting experiments on that. Coal doesn't seem to do the trick, especially on large lobsters. We study Norway lobsters, langoustine, and they didn't die as fast even in the freezer in minus 20. So we think the best method will be electro shock because it renders them unconscious really fast. We are trying to investigate that more, but I think many companies are trying to implement electrical stunning as a better method than chilling.