Even animals without hands can display handedness--or, at least, a preference to do things with one side of the body rather than the other. Animals ranging from primates to birds to invertebrates have been shown to favor their left or right side. Fish might reveal that preference by choosing to swim right, for example, when avoiding a predator. Don't get too charmed by the idea of left-handed and right-handed fish, though: In a warming world, they may disappear.
A new study by researchers in Italy and Australia looked at young coral reef fish, Neopomacentrus azysron, which often display a preference for the right or left side. (Humans are unusual in that almost all of us prefer the right side. In other animals, individuals might be biased toward one side or the other, but the population as a whole tends to be evenly distributed.) To measure the reef fishes' preference, the ...
