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Environmental Genomics
Origins of biodiversity
Ancient origins of internal clocks
Scientists studying how ragworms (Nereis virens) manage their internal clocks have found that they possess many genes that are the same as the clock genes in other organisms as diverse as fungi, insects and humans.
Terrestrial organisms have clocks mostly based on a 24-hour cycle (circadian clocks). The scientists have demonstrated that ragworms also have clocks based on the tides. Both clocks might be variants of a common ancestral clock which evolved over 1.5 billion years ago. At this time the world rotated faster than it does now, so a day was only about 12 hours long – around the length of the current tidal cycle.