Even the largest animal that ever lived has rhythm—the blue whale performs acrobatic dives and twirls as it gobbles up microscopic krill by the millions.

But a new study adds a surprising new detail to the marine mammals' underwater ballet: They don’t spin and turn at random. Instead, the 80-foot-long giants show a preference for either their right or left side—the equivalent of handedness in humans. (Watch a blue whale lunge for its dinner.)

Although blue whales mostly spend their lives below the surface, the majority of what we know about them comes from brief glimpses at the surface.

So study leader Ari Friedlaender, a marine biologist at the University of California, Santa Cruz and at Oregon State University, set