University of Gothenburg researchers have provided scientific proof that shore crabs feel pain, urging a reevaluation of how shellfish are treated under EU animal welfare laws. This evidence supports the development of less painful methods for killing shellfish.
In our pursuit of improving the welfare of animals we consume, certain creatures are often overlooked. Researchers at the University of Gothenburg are now focusing on decapod crustaceans, which include shellfish delicacies such as prawns, lobsters, crabs, and crayfish. Currently, shellfish are not protected under animal welfare legislation in the EU, but this might be about to change—for a good reason, according to researchers.
Their study, recently published in the journal Biology, provides the first evidence that painful stimuli are sent to the brain of shore crabs, offering more proof that crustaceans feel pain.
“We need to find less painful ways to kill shellfish if we are to continue eating them. Because now we have scientific evidence that they both experience and react to pain,” said Lynne Sneddon, zoophysiologist at the University of Gothenburg.
Several research groups have previously conducted a number of observational studies on crustaceans, in which they were subjected to mechanical impact, electric shocks, or acids to soft tissues such as the antennae. These crustaceans reacted by touching the exposed area or trying to avoid the danger in repeated experiments, leading researchers to assume that they feel pain.
Pain Receptors in the Soft Tissues
The researchers at the University of Gothenburg are the first to carry out neurobiological studies by measuring the activity in the brain of a shore crab, through an EEG style measurement.
“We could see that the crab has some kind of pain receptors in its soft tissues, because we recorded an increase in brain activity when we applied a potentially painful chemical, a form of vinegar, to the crab’s soft tissues. The same happened when we applied external pressure to several of the crab’s body parts,” says Eleftherios Kasiouras, PhD student at the University of Gothenburg and lead author of the study.
The activity of the central nervous system in the brain was measured in the crab when the soft tissues of claws, antennae, and legs were subjected to some form of stress. The responses show that shore crabs must have some form of pain signaling to the brain from these body parts. The pain response was shorter and more powerful in the case of physical stress than in the case of chemical stress, which lasted longer.
Advocating for Humane Treatment
“It is a given that all animals need some kind of pain system to cope by avoiding danger. I don’t think we need to test all species of crustaceans, as they have a similar structure and therefore similar nervous systems. We can assume that shrimps, crayfish and lobsters can also send external signals about painful stimuli to their brain which will process this information,” says Kasiouras.
The researchers point out that we need to find more humane ways to handle and even kill crustaceans. At present, it is allowed to cut up a crustacean alive, unlike the mammals we eat.
“We need more research to find less painful ways to kill shellfish,” says Sneddon.
Reference: “Putative Nociceptive Responses in a Decapod Crustacean: The Shore Crab (Carcinus maenas)” by Eleftherios Kasiouras, Peter C. Hubbard, Albin Gräns and Lynne U. Sneddon, 21 October 2024, Biology.
DOI: 10.3390/biology13110851
