A recent study showed that there are unusual reactions among crabs to each other during times of "crisis". In some cases, crabs attempted to revive another crab that had lost consciousness, grabbing it or even pulling it toward themselves to clear its breathing paths.
There are rare reports of large social malacostracans that attempt to help their fellow species, such as dolphins, which try to push a distressed individual to the water's surface.
Recently, Li Chang and his colleagues from California State University observed crab behavior in the laboratory when they presented a familiar partner in a cell that had been both active and intoxicated.
During a series of tests, the crabs spent about 47% of the observation time, on average 13 minutes, interacting with the lost consciousness partner, and they did this in three ways. Zhang explained that crabs "start with sniffing, then exhibit personal care, and afterward switch to very intensive or physical interaction". They not only surrounded and nibbled the area around the rta, but also pulled the partner's antennae in more than 50% of cases.
In a separate test, researchers carefully placed an inert plastic ball in the mouth of a non-responsive crab.
