Monday, April 12, 2010

Centipedes Are Quite Odd

Of the 3000 centipede species described world wide, each one has an odd number of segments, ranging from 15 to 191. Chipman et al. (Current Biology 14 pp. 1250–1255, 2004) report that variation in segment number is caused by variation in the number of cycles of a primary segmentation oscillator, each cycle of which generates two segments.

Interestingly, the genes responsibly for this double segmental periodicity in centipedes (odd-skipped and caudal) are homologues of Drosphilia genes (Nüsslein-Volhard and Wieschaus, 1980 Nature 287 pp. 795-801). These genetic similarities may be a result of evolutionary convergence or could be an indication of a common ancestor of both flies and centipedes (Damen, 2004 Current Biology 14 pp. R557–R559). This may help shed some light on the relatedness of the myriopods to the other arthropod groups.

Lithobius forficatus

Haplophilus subterraneus

Ireland has 26 species described, from the families Himantariidae, Schendylidae, Geophilidae, Cryptopsidae, Lithobiidae and Henicopidae (Ferriss et al. (eds.) Irish Biodiversity: a taxonomic inventory of fauna, Irish Wildlife Manuals, No. 38, 2009).

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