Crustacean Cognition

As far as mental acuity goes, crustaceans have been considered to be near the bottom, when evaluating the brains of various families of animals. Crustaceans are arthropods, which include other simple critters like insects and spiders. In particular, crustaceans are hard-shelled animals (the root of the word crustacean is “having a crust”), such as lobsters, crabs, crayfish, and shrimp. Until a couple of years ago, many scholars thought that the brains of crustaceans are so primitive that they can't even feel pain. This allowed seafood lovers to plunk a live lobster in a pot of boiling water, conscience free, believing it to be so stupid that it did not suffer. Now we know better.

A recent scientific finding coming out of the University of Bordeaux shows us that crustaceans are not only able to feel pain, but possess an even greater cognitive ability: they also feel stress. In fact, the study showed that their tiny brains are influenced by some of the same chemicals that our massive human brains respond to. Ahh, I love it... one more belief about the uniqueness of the human species gets shattered. We keep finding evidence that narrows the gap between us and all the other animals. And here's yet another one.

The research conducted by the French scientists conclusively showed that crayfish can experience rudimentary emotions. How? When they gave crayfish a mild electric shock, the creatures hid in dark corners of their aquarium—unlike their unshocked brethren, who did not hesitate to boldly venture into the light. And the shocked crayfish behaved as if they were stressed or shy.

Wondering what might be going on chemically within the tiny crayfish brain, the researchers guessed that it could be due to elevated levels of serotonin—which also affects the moods of humans, when a serotonin imbalance occurs in our brains. When they injected the stressed crayfish with a drug used to treat anxiety in humans, the critters calmed down and began venturing into the light. Crayfish on Prozac!

I don't think that these results imply that we need to begin training crustacean shrinks to counsel depressed lobsters and crayfish. But they do tell us that yet one more mental barrier between us and simple animals has been dismantled. It makes sense that all animals—including humans—have many mental similarities, given that we all have evolved from the same primitive ancestor that came into being some 3.5 billion years ago. We're all together!