Strigamia live underground and have no eyes, so it is not surprising that many of the genes for light receptors are missing, but they behave as if they are hiding from the light
— Michael Akam
An international team comprising more researchers than the arthropod has legs (106 researchers) has sequenced the genome of Strigamia maritima, a Northern European centipede, and found that its genome, while less than a tenth the size of a human’s, has around two-thirds the number of genes, distributed across one pair of large chromosomes and seven pairs of tiny ones, including X and Y sex chromosomes. The results are published in the journal PLOS Biology.
Arthropods are the most species-rich group of animals on Earth. There are four classes of arthropods alive today: insects, crustaceans, chelicerates (which include spiders and scorpions) and myriapods. This latter class, which includes centipedes, is the only class for which no genome has yet been sequenced.
Myriapods arose most likely from marine ancestors that invaded the land more than 400 million years ago. All myriapods have a large number of near-identical segments, most bearing one or two pairs of legs. However, despite their name, centipedes never have a hundred legs. Strigamia maritima, which lives in coastal habitats, can have from 45 to 51 pairs – but the number of pairs is always odd, as it is in all centipedes.
The team found that the centipede genome is more conserved than that of many other arthropods, such as the fruit fly, with less gene loss and scrambling. This suggests that the centipede has evolved slowly from their common ancestor and should allow researchers to draw comparisons between very different animals, which are not obvious when working with fruit flies or other fast evolving insects. For example, the researchers found parallels in the way that the brain is patterned between centipedes and other very distantly related animals such as marine worms. Such comparisons will enable scientists to build an overall picture of how genetic changes underlie the diversity of all animals.
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Image Strigamia maritima male, Loch Linnhe, Scotland
Credit: Anthony Barber
Reproduced courtesy of the University of Cambridge
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