It could prick the conscience of seafood chefs everywhere. Prawns, lobsters and other invertebrates may feel pain, a controversial finding that could open up the debate on animal welfare.
Robert Elwood at Queen鈥檚 University Belfast in the UK and his colleagues claim they have found convincing evidence that prawns do feel pain. When they dabbed an irritant 鈥� acetic acid 鈥� onto one of 144 prawns鈥� two antennae, the creatures reacted by grooming and rubbing the affected antenna for up to 5 minutes. This focused reaction is similar to that seen in mammals exposed to a noxious stimulant (Animal Behaviour, ).
Elwood says the results show a centrally organised response to the irritant. 鈥淭he prolonged, specifically directed rubbing and grooming is consistent with an interpretation of pain experience,鈥� he says.
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Most researchers believe that only vertebrates feel pain, but Elwood argues that this is unlikely because of the benefits that pain confers. Feeling pain enables an animal to learn from a potentially damaging experience and modify its behaviour, improving its chances of survival, he says.
Others disagree. 鈥淪hrimps do not have a recognisable brain,鈥� and are incapable of feeling pain, says Lynne Sneddon at the University of Liverpool, UK, who has researched whether fish feel pain. 鈥淵ou could argue the shrimp is simply trying to clean the antenna rather than showing a pain response,鈥� she says.
Richard Chapman at the University of Utah鈥檚 Pain Research Center in Salt Lake City agrees. Most animals possess nociceptors 鈥� sensors that trigger responses to irritants. 鈥淓ven a single-cell organism can detect a threatening chemical gradient and retreat from it. But this is not sensing pain,鈥� he says.
Elwood insists that such comparisons are flawed. 鈥淯sing the same analogy, one could argue crabs do not have vision because they lack the visual centres of humans,鈥� he says. He hopes his work will encourage research into whether crustaceans have the neurological architecture that could produce a pain response. 鈥淗owever, there seem to be a multitude of reasons that stop people wanting to enquire about pain in invertebrates,鈥� he adds.
