Special Topics
Power in Many Annelida of Boring into Hard Substances
Boring and burrowing in sand, mud, and earth are very general in the Annelida. Glycera and Nephthys, for instance, disappear with great rapidity amongst sand by boring with their proboscides, the former passing its elongated organ through a considerable space in a single thrust. Eteone and Ammotrypane carry their bodies swiftly through moist sand and gravel. Others penetrate muddy clay and the debris in fissures of rocks. The labours of the earthworm in passing through the soil only require indication; and the Gephyrea and some leeches show the same habits in clay and mud.
Certain Polychaeta and Gephyrea have also the power, in common with cirripedes, mollusks, Bryozoa, and sponges, of perforating rocks, stones, shells, and other solid media. The most conspicuous forms are Polydora (fig. 21), Dodecaceria, Sabella saxicava, and Phascolosoma Johnstoni. Though such annelids are very abundant in corals, limestone, chalk, and shells, yet their occurrence in large numbers in aluminous shale and sandstone shows that their perforations are not necessarily due to an acid. The influence of the boring annelids in disintegrating the foregoing substance is considerable. (W.C.M.)
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Annelida - Table of Contents
The above article was written by William Carmichael McIntosh, M.D., LL.D., F.R.S., Professor of Natural History at the University of St. Andrews; Director of the University Museum; author of Monograph of British Annelids and The Resources of the Sea.
