It was thought that only humans and "intelligent" animals could experience anxiety – but this research suggests that crayfish may experience a form of this emotion too.
When the crustaceans were exposed to a stressful situation – in this case an unpleasant electric field – they subsequently behaved far more cautiously, staying hidden in the darker parts of their tank.
But when the stressed crayfish were given an anti-anxiety drug, they stopped being so wary and moved into light, more exposed areas.
The fact that these animals may get anxious adds to a number of studies that suggest crustaceans also feel pain. Scientists say it suggests the welfare should be improved for these creatures, which are not currently classified as sentient by the food industry.
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area where there is a force generated by an electric charge
on guard; looking out for danger
health and happiness; well-being
designated, considered as
able to experience sensations and feelings