Tiny Sea Louse Has Extra Body Clock

The speckled sea louse may be only 5mm long, but it's got something you don't: an extra body clock. Like humans and other creatures, the sea louse has one body clock that follows the circadian rhythms of night and day. But scientists have found the first molecular proof of a second internal clock in the lice—this one for ocean tides, reports Nature. The BBC helps bring the point home: Even when removed from their natural habitat and placed in a lab setting, the little guys swam every 12.4 hours as if the tides were changing.

"The identification of the tidal clock as a separate mechanism now presents us with an exciting new perspective on how organisms define biological time," says the senior UK researcher in PhysOrg. "It is a completely unexplored field." The scientists concluded the tidal clock was a separate entity after effectively shutting off the night-and-day clock in their controlled lab setting. The two "run side by side but use largely different and independent molecular clockwork mechanisms," explains a post at the Naked Scientists blog. "What the mechanism is though, as yet remains a mystery." In other animal-kingdom news, we've got photographic proof that deer should fear eagles.)

Read more here. (More circadian rhythms stories.)