The ultrastructure of tube
SEM photographs by Vinn & Dunca

Ditrupa arietina, external FP layer


D.arietina, external FP layer


D.arietina, external FP and internal CCL layer


Spirorbis sp., CCL structure

The tube wall of Ditrupa arietina is composed of two layers (ten Hove and Smith 1990), separated by the discontinuity surface (Figure B). The inner layer has a fine complex crossed lamellar structure (see Carter 1990, p. 623, fig. 36). The layer is composed of needle shaped crystals, which are 4.0-7.0 μm long and 0.4-0.5 μm wide. The external layer of the tube in D. arietina has an irregular fibrous prismatic structure. The prisms, 30-40 μm long and 1.0-2.0 μm wide, are dissected by thin organic rich films giving to them streaky appearance. Similar incremental zonation of fibres is described in the scleractinian corals (Jell 1974). The dimensions of crystal sections forming the prisms are about 0.9 – 1.7 μm long and 1.0-2.0 μm wide.


Carter, J. G., K, Bandel, V. de Buffrénil, S. J. Carlson, J. Castanet, M. A. Crenshaw, J. E. Dalingwater, H. Francillion-Vieillot, J. Géradie, F. J. Meunier, H. Mutvei, A. de Riqlés, J. Y. Sire, A. B. Smith, J. Wendt, A. Williams, and I. Zylberberg. 1990. Glossary of Skeletal Biomineralization. In: Carter, J. G. (ed.) Skeletal Biomineralization: Patterns, Processes and Evolutionary Trends, Vol. I, p. 609-671.

Hove, H. A. ten and Smith, R.S. 1990. A re-description of Ditrupa gracillima Grube, 1878             (Polychaeta, Serpulidae) from the Indo-Pacific, with a discussion of the genus. Records of the Australian Museum 42, 101-118.

Jell, J.S.1974. The microstructure of some scleractinian corals. In: Proceedings of the Second International Coral Reef Symposium, 2. Great Barrier Reef Committee, p. 301-320. Brisbane.