sciencehabit writes "Almost all organisms, from bacteria to mammals, have a circadian clock—a mechanism in their cells which keeps them in sync with Earth's day-and-night cycle. But many organisms follow other rhythms as well. Now, new research provides the first evidence that animals have molecular cycles independent of the circadian rhythm. They include a sea louse whose swimming patterns sync up with the tides, and a marine worm that matures and spawns in concert with the phases of the moon. The discoveries suggest that noncircadian clocks might be common and could explain a variety of biological rhythms."