Sea louse with second body clock
11 Nov 2013 by Evoluted New Media
The tiny speckled sea louse boasts not one but two body clocks – one for night and day, and one for the ebb and flow of the tide.
While the body clocks of land-dwelling organisms are regulated by light and dark – the circadian clock – things are a little more complex for sea-dwelling organisms, which also have to contend with other regular changes to their environment, like tides.
Researchers from Aberystwyth, Bangor, Cambridge and Leicester Universities have for the first time confirmed the existence of a distinct and independent circatidal body clock which follows the 12.4 hour cycle of the tides.
“The discovery of the circadian clock mechanisms in various terrestrial species from fungi to humans was a major breakthrough for biology,” said Dr David Wilcockson, aquatic biologist at Aberystwyth and senior author of the paper published in Current Biology.
“The identification of the tidal clock as a separate mechanism now presents us with an exciting new perspective on how organisms define biological time. It is a completely unexplored field.”
By using genetic, pharmacological and in vitro cell biology techniques and providing continuous light under laboratory conditions, researchers were able to turn off the circadian clock in the speckled sea louse, Eurydice pulchra.
Despite this, and being removed from its natural environment – sandy beaches where they can burrow into the sand as the tide leaves, and resurface to feed when it returns – the louse continued to swim every 12.4 hours for several days. Researchers argue this provides incontrovertible evidence that the 5mm louse possesses two separate and independent body clocks.
Wilcockson believes it is important to explain the cellular and molecular mechanisms of tidal clocks for many reasons:
“Firstly, the speckled sea louse evolved many millions of years before mammals and represents a simplified model that we can use to help understand the clocks of more complex animals. Secondly, a deeper appreciation of rhythms in marine organisms could have implications for the welfare and productivity of cultured marine species and our understanding of the behaviour of commercially important ones.”
The researchers believe that unrelated species found in parallel environments may have developed a similar solution to the same problem.
“There is tremendous diversity in the oceans and biology is so inventive that it may have come up with many different solutions exploiting various mechanisms to solve the same challenges of life,” Wilcockson said.
Dissociation of Circadian and Circatidal Timekeeping in Marine Crustacean Eurydice pulchra http://www.cell.com/current-biology
