New research has demonstrated that crustaceans are likely capable of feeling pain, but will this finally be enough to prevent people from boiling them alive?
New Research into Decapod Crustaceans
Testing animals like crustaceans for pain has been difficult because facial and auditory clues cannot be measured like they would be in other animals. However a demonstration of rapid learning after painful stimuli was, researcher Prof Bob Elwood from Queen’s University Belfast concluded, a key indicator of a pain response over a simple “nociception” response, this the term given to the reflex withdrawal of a limb following noxious stimuli that doesn’t require higher cognitive function.
Most importantly, this rapid learning could be tested for in the lab. Therefore, Elwood and his team devised a series of experiments involving 90 shore crabs.
They took the crabs and individually placed them in a brightly lit chamber. The researchers exploited the crabs’ natural instinct to run for cover by creating two dark shelters within the chamber, one of which was to be the “wrong” shelter. Then, through a series of 10 trials, every time the crabs entered the “wrong” shelter, they were given a mild shock to their legs.
Those crabs that received a shock during the trial were, by the third run through, switching their choice of shelter during subsequent tests, potentially indicating that not only had they felt the painful stimuli but, crucially, that they were discriminating on that basis.
Furthermore, during the trial many of the crabs did something that would normally go against their instincts: they shunned the usual safety of their dark shelters and remained in the lit area, seemingly to avoid the risk of shock. An increasing number of crabs demonstrated this behavior throughout the rest of the trial.
Researchers, publishing in the Journal for Experimental Biology, say this set of results, along with data collected in previous years, shows that the shore crabs demonstrate key criteria for pain experience and that the results were broadly similar to those in vertebrate studies.
Some in the field have not been convinced by these findings however. Reports the Guardian:
“It looks to me that the authors have demonstrated that crabs move away from a potentially damaging stimulus,” said Dr Magnus Johnson, a lecturer in environmental marine biology at the University of Hull. “That doesn’t necessarily mean that they sense ‘pain’.”
Prof Paul Hunt, emeritus professor of biology at the University of Leicester agreed. “I don’t think you can really say scientifically that animals, like a crab, can be aware of a sensation that we know as pain … we just don’t know.”
Still, a number of other non-affiliated scientists have said this research provides a basis of thought that decapod crustaceans certainly might feel pain. Francesca Gherardi, an evolutionary biologist at the University of Florence in Italy, says, “It is avoidance learning that makes the difference,” and that more research should be done to assess the crustacean’s discrimination abilities between painful and nonpainful situations.
With billions of crabs and lobsters being dismembered and boiled alive every year in the culinary industry, Professor Elwood is adamant that these results, at the very least, should begin a wider debate about how we treat crustaceans.
“You have the most extraordinary treatment of these animals … even if there’s a slight chance they feel pain, I feel we should start attending to that now,” Elwood says. “You have lobsters being processed, prawns that are being processed live by the front end, the head and the thorax being torn off. And the head with the brain will carrying on being a viable nervous system and will continue to go on like that for an hour or so.”
There’s more research to be done. Elwood’s next job will be to assess whether stress hormones in the crab rise after painful stimuli, another key indicator of a pain experience. If they do, that would appear to go a long way in confirming these finding. If not, it would speak against pain experience.
While this research has been called compelling, and indeed builds on a body of evidence that already exists, animal welfare standards throughout the EU and most of the world in fact fail to grant meaningful welfare protections to crabs, lobsters and shellfish, something that seems unlikely to change in the near future unless studies like these are given the attention they deserve.
Image credit: Thinkstock.