Crayfish may experience form of anxiety

Jun 14, 2014

By Rebecca Morelle


Crustaceans may be able to experience some emotions, a study published in the journal Science suggests.

Researchers in France have found that crayfish seem to show anxiety, a feeling previously thought to be too complex for these primitive animals.

It follows a number of studies that suggest that crustaceans can also feel pain.

Some experts say the seafood industry may need to rethink how it treats these creatures.

Dr Daniel Cattaert, from the University of Bordeaux, who carried out the research, said: “Crayfish are primitive, they have been around for hundreds of millions of years.

“The idea that this animal could express some anxiety didn’t seem possible, but with our experiments we’re more and more convinced that this was the case.”

Stressed out

To investigate, the scientists exposed the crustaceans to a stressful situation – in this case an unpleasant electric field.

The creatures were then placed into a cross-shaped tank. Two of the arms of the cross were dark – an environment that most crayfish prefer, while two were light.

Dr Cattaert said: “When you have a naive crayfish (one not exposed to the electric field), you observe that the animal will go in all of the arms, but with a slight preference for the dark arms.

“But when we place a stressed animal in the maze, we observe the animal never goes in the light arms.

“The light arms are perceived as too threatening.”

The researchers found that the crayfish produced high levels of serotonin, a chemical that is released by the brain to counteract anxiety.

They also discovered that when they injected the stressed creatures with an anti-anxiety drug, they stopped being so wary and began to explore the light arms of the tank.

3 comments on “Crayfish may experience form of anxiety

  • Thanks for the link! Quite a read. It took about half an hour for me to get through it, but the writing was so fluent I didn’t mind.

    Also don’t mind saying some parts were pretty chilling, especially about how lobsters were dispatched for the pot. I had an inkling about the findings of research on lobster consciousness and neuroanatomy, but it’s quite something to have the details brought back to you while reading about the owner of said consciousness thrashing about in hot water or being pulled apart while still alive.

    Thank goodness I don’t eat lobster. I’d either be put off it permanently or try to compartmentalize the discomforting emotions.

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  • I think it likely that the relatively small network of cells required to support consciousness in humans may be smaller still in less sophisticated creatures, i.e. creatures whose brain and nervous systems deliver a lower volume of stimuli to that network. Hence it’s most likely that small creatures like crayfish are able to experience something akin to human emotional responses.

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