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Extra biological clocks guide animals

NZ Newswire logoNZ Newswire 4 days ago

The study of a small, sand-dwelling crustacean on Piha Beach has shown many animals march to the beat of more biological clocks than humans, a team of Kiwi scientists say.

The so-called circadian clock, which helps regulate human behaviour in tune with the cycle of day and night, is well studied, including where it is located in the human brain and the genes involved, the University of Auckland team says.

But just how the "extra" biological clocks found in many animals work to regulate their feeding or reproduction so that they match tidal or lunar cycles remains unclear, the scientists say.

To study this, they looked at Piha's nocturnal sand burrowing isopod, Scyphax ornatus.

It leaves its burrow at night to feed on plant and animal waste but also knows when every half cycle of a lunar month arrives (approximately every fortnight) to allow it to maximise its time between tides seeking food.

To test if it would behave the same inside a laboratory, the scientists first kept the animals in completely dark and stable conditions and observed that they kept almost the same routine as in the wild.

But when the scientists artificially changed the hours of light and tidal conditions the animals were exposed to, they began to change their routines.

The university team concluded this meant the animals not only had a circadian clock, operating according to day and night, but another internal biological clock that used this information to then predict the lunar half-cycles.

"That tells us their semilunar or fortnightly behaviour continues to be regulated by the interaction of circatidal and circadian clocks," researcher Dr James Cheeseman said.

Fellow researcher Professor Mike Walker said lunar and tidal behaviour in animals was also well known by early Maori, who followed a fishing and planting calendar based on each cycle of the moon.

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