Monday, August 16, 2010

Scuttle, Scuttle, Scuttle: Its a Bristletail

Petrobius maritimus

Look among the crevices of the upper shore and splash zone of an Irish rocky shore and you will encounter a small, scurrying insect no more than 15 mm in length, often in large numbers. Indeed these creatures are to found in caves and other regions above the high tide mark where they feed on detritus, green algae and lichens. These are members of the Archaeognatha, the bristletails. Four species of Archaeognatha occur in Ireland: the local occuring Dilta saxicola and D. hibernica and the widespread Petrobius brevistylis and P. maritimus (Ferriss et al., 2009 Irish Biodiversity: a Taxonomic Inventory of Fauna p.97). P. maritimus is by far the most common in Ireland. It has an elongated body, with an eleven segmented body (Sterry, 2004 Collins Complete Guide to Irish Wildlife p. 122). Three filaments at its tail end explain it its bristletail moniker and its antennae are noticeably long. These features combined with its dense scale cover and its ability to jump give them protection against predators (Sturm, 2009 Encyclopedia of Insects pp. 48-50). Archaeognatha are quite an ancient class of insects which can be seen in their lack of wings and lack of true metamorphosis (Linssen, 1987 Insects of the British Isles pp. 39-40).

Petrobius maritimus

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