Do Crustaceans Feel Pain? Study Demonstrates Existence of Nociceptive Responses in Shore Crabs | Sci.News

Nociceptors are receptors that detect injurious stimuli and are necessary to convey such information from the periphery to the central nervous system. Crustaceans, such as shore crabs, are widely used in science and aquaculture. Understanding whether they can experience pain is essential for improving their welfare. One key criterion for assessing pain is the presence of nociceptors. In a new study, scientists from the University of Gothenburg, the Universidade do Algarve and the Swedish University of Agricultural Sciences investigated the existence of nociceptors in shore crabs (Carcinus maenas) by examining the central nervous system response to two types of potentially noxious stimuli, i.e., mechanical and chemical or acetic acid. Their results indicate that 32 areas around the crab’s body exhibited putative nociceptive responses that respond to a noxious chemical, with many areas having additional mechanical sensitivity.

Recent scientific evidence suggests that decapod crustaceans such as lobsters, crabs, prawns, crayfish, and shrimps may be able to experience pain.

However, information on the presence of nociceptors, i.e., receptors that detect noxious stimuli, remains limited.

While nociceptive or pain-related behaviors have been observed, electrophysiological evidence of nociceptors is needed to identify which types of injurious stimuli may be painful.

“We need to find less painful ways to kill shellfish if we are to continue eating them,” said Dr. Lynne Sneddon, a zoophysiologist at the University of Gothenburg.

“Because now we have scientific evidence that they both experience and react to pain.”

In their study, Dr. Sneddon and colleagues investigated the existence of nociceptive responses in various soft tissues across the bodies of shore crabs.

This crustacean species was chosen as a model due to its widespread distribution and well-documented physiology.

Electrophysiological recordings were conducted on the brain or the circumesophageal ganglion in response to mechanical and noxious stimuli.

“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,” said Eleftherios Kasiouras, a Ph.D. student at the University of Gothenburg.

“The same happened when we applied external pressure to several of the crab’s body parts.”

“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.”

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,” Dr. Sneddon said.

The study was published on October 22, 2024 in the journal Biology.

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Eleftherios Kasiouras et al. 2024. Putative Nociceptive Responses in a Decapod Crustacean: the Shore Crab (Carcinus maenas). Biology 13 (11): 851; doi: 10.3390/biology13110851