Crawfish, Like Humans, Get Stressed Out, Too

Make no mistake--humans aren't the only species to get bent out of shape by stress. Now, a recent study published in the journal Science shows that crawfish also experience human-like anxiety. Fortunately, just like humans, researchers from the University of Bordeaux in France found that these crustaceans can also be calmed with the appropriate medications.

For the experiment, lead study author Dr. Daniel Cattaert of the university and colleagues administered a series of mild shocks to crawfish before putting them into an aquarium "maze" that housed both well-lit and dark burrows. Researchers found that the crawfish were typically happier in darker environments and tended to avoid lighter areas due to increased levels of serotonin in the brains of the crawfish when they entered the light. Injecting crawfish with serotonin also exhibited a similar nervous response.

However, while increased serotonin levels in humans may help lower depression, it showed the opposite effect on these crustaceans.

"Analyses of this ancestral behavior in a simple model reveal a new route to understanding anxiety and may alter our conceptions of the emotional status of invertebrates," researchers noted, in a news release.. "[Our results] emphasize the ability of an invertebrate to exhibit a state that is similar to a mammalian emotion."

Fortunately, the researchers finally gave the tiny crustaceans a break with an injected dose of chlordiaepoxide, a sedative also used to treat anxiety in humans. This had a calming effect on the crawfish, helping them return to their normal behaviors.