An experiment has shown that the freshwater crayfish can be induced into a state of deep anxiety that can only be alleviated by the same kind of tranquilisers used to treat people afflicted by a similar condition, scientists said.

The study revealed that the crayfish emotion is governed by the same chemical transmitters in its nervous system that are involved in controlling anxiety in humans, which is why anxious crayfish respond to benzodiazepine, a tranquiliser used to treat anxiety in people.

Dr Daniel Cattaert from the University of Bordeaux:

“There is a difference between fear and anxiety. Fear is an emotion you express when you face danger. Anxiety is a response to fear, an animal won’t want to face the same problem again and so will feel anxiety.

“All the elements that are needed for an animal to express anxiety are present in animals as simple as the Crayfish. This doesn’t mean they have the same feeling as us because the level of emotion we feel is much larger. We were interested in protective adaptation behaviour in Crayfish, in situations when an animal faces danger and it escapes but doesn’t adapt then it will die. However if it does adapt then it has more chance of surviving. The anxiety we have studied is beneficial for the animal.

“We should revaluate how we treat animals. They have anxious behaviour but not necessarily consciousness. If they are conscious of themselves then we have a big problem.”