Many of us see somebody moving around, and assume that the person is alove. Not so with Argentine ants. If they think a fellow ant is dead, they'll carry it off to the trash heap, even if the poor creature is still moving.
The reason for this behavior is that during their lifetime, Argentine ants emit a chemical signal to signify that they are alive. Biologist Dong-Hwan Choe recently discovered that if he inhibited that chemical, the colony's undertakers would decide that the ant was dead and would proceed to dump it out back, no matter how much the still-living victim protested.