A Blog Around The Clock

Biological Effects of the Moon

I rarely write about biological rhythms outside of circadian range (e.g., circannual, circalunar, circatidal rhythms etc.), but if you liked this post on lunar rhythms in antlions, you will probably also like this little review of lunar rhythms in today’s Nature:

Pull of the Moon:

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Studies of fiddler crabs, for example, have shown that even when kept in the lab under constant light and temperature, the animals are still most active at the times that the tide would be out. A similar internal ‘circalunar’ clock is thought to tick inside many animals, running in synchrony with the Moon and tides, and working in conjunction with the animal’s 24-hour circadian clock. This is thought to help animals anticipate tide movements; a skill that might give some creatures an edge. Ecologist Martin Wikelski of Princeton University, New Jersey, has found for example, that Galapagos marine iguanas with the most accurate circalunar clock are more likely to survive tough times, presumably because they are best at reaching feeding spots first.

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Moonlight can also change animal behaviour. Many marine organisms move up and down in the sea depending on the level of moonlight in order to keep their light levels constant. On land, some nocturnal animals come out on a well-lit night to hunt, others stay hidden to avoid predators.

And African dung beetles, oddly, can walk in a straighter line when the Moon is out: Eric Warrant at the University at the University of Lund, Sweden, and his colleagues reported in 2003 that Scarabaeus zambesianus can detect the pattern of polarized moonlight in the night sky and use it to navigate2. This means they can roll their dung balls in a straight line on a moonlit night.

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And yeah, for the anthropocentric readers, the article has a bunch on humans as well….