WASHINGTON, D.C.––The timing of the National Zoo’s June 22, 2014 closure of its 27-year-old invertebrate house could be called insensitive. The bughouse closure comes just a week after the journal Science boosted interest in invertebrates by publishing findings that crayfish not only feel pain, but feel stress when they anticipate that pain may occur.
“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,” University of Bordeaux researcher Daniel Cattaert told BBC News science correspondent Rebecca Morelle.
Aware that crayfish normally prefer darker water, Cattaert and team gave several crayfish a series of mild electric shocks, then compared the responses of the crayfish who had been shocked with those of other crayfish in a maze containing both well-lit and darkened paths.
Crayfish who had not been shocked preferred the dark paths, as expected, but also explored the lit regions.
Crayfish who had received the shocks rarely entered the lighted parts of the maze.
Light avoidance was linked to raised levels of the neurotransmitter chemical serotonin, which also influences human moods. Injecting crayfish with serotonin made them anxious, while dosing them with the tranquilizer chlordiazepoxide had the opposite effect.
The findings “may alter our conceptions of the emotional status of invertebrates,” Cattaert projected. “Our results emphasize the ability of an invertebrate to exhibit a state that is similar to a mammalian emotion.”
Commented Queens University at Belfast researcher Robert Elwood, who has published several earlier landmark studies of the crustacean capacity to feel pain, “I think it must be regarded as a possibility that they experience anxiety and pain. And if we consider there is a possibility, then effective safeguards against inflicting pain should be taken just to be on the safe side, and we should also ensure they are killed rapidly.”
Costing about $1 million a year to operate, the National Zoo invertebrate house was closed, director Dennis Kelly told media, because it was not funded in either the zoo’s five-year plan or a 20-year master plan.
“Plans call for a future Hall of Biodiversity, including invertebrates,” wrote Brett Zongker of Associated Press.
“Some of the animals––the hissing cockroach, the bird-eating tarantula, the peppermint shrimp, among others––may be sent to other zoos,” reported Michael Ruane of the Washington Post. “Some may be moved to other locations in the zoo. Some may have to be euthanized if new homes can’t be found.”