We’ve blogged before about circadian rhythms (rhythms in nature that follow the daily cycle of sunlight and darkness) but interesting research published in Current Biology and Cell Reports has found that some marine animals have at least two internal clocks, which crucially follow different times and have different mechanisms.
“This is the first molecular evidence that the clocks aren’t the same,” says Chris Chabot, a biologist at Plymouth State University in New Hampshire.
Whilst circadian rhythms are found in every kingdom of life, non-circadian rhythms are much less well understood.
The two marine organisms investigated (the speckled sea louse and the bristle worm) show biological rhythms that are influenced by the Moon, as well as possessing a circadian clock.
Importantly the circadian and non-circadian rhythms work in parallel and use different molecular mechanisms.
The speckled sea louse was discovered to follow a 'circatidal' rhythm (in time with the tides), which repeats every 12.4 hours. It’s swimming pattern synchronised with the tides, but importantly other biological cycles synchronised with day and night. This showed that each cycle is controlled by an separate internal clock, which is set by, but can also run independently of, external stimuli — in this case, light (or lack thereof) and turbulence (as the tide changes).
The bristle worm instead was found to follow a 'circalunar' rhythm (following the waxing and waning of the Moon). The 30 day cycle governs spawning whereas the worm also has a circadian feeding rhythm as it always emerges to feed at night.
In both species, the 'circatidal' or 'circalunar' continued to ‘tick’ even if the circadian rhythm was totally disrupted.
All this suggests that there is much left to discover about how time is kept inside more complex organisms, including humans.
At doppel we’re fascinated by different rhythms in nature and we’re excited to see where this leads!