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The structure and composition of the teeth and grasping spines of chaetognaths

  • Q. Bone (a1), K. P. Ryan (a1) and A. L. Pulsford (a1)
Abstract

The teeth and grasping spines of Sagitta are similar in structure, both having a central pulp cavity surrounded by two electron-dense chitinous layers. The cells of the pulp cavity contain microtubules arranged along the long axis. The two chitinous tubes are separated by a less-dense zone crossed by coarse fibrils linking the two. The teeth and spines insert into less electron-dense chitin (presumably flexible) and are moved by processes of anchor cells which pass into the basal chitinous zone. The inner region of the anchor cells is apposed to the connective tissue layer on to which the muscles of the teeth and spines insert. At the base of the pulp cavity, i.e. at the secretory zone where the teeth and spines are formed, the cells of the pulp cavity contain electron-dense granules in which zinc is found; zinc is also present in the inner and outer dense chitin layers at high concentration (0·5–1·0% of the dry wt).

Both spines and teeth are tipped with fibrous cones containing silicon. It is suggested that the zinc associated with the chitin serves to toughen the teeth and spines and render them less liable to fracture, and that the silicon in the tips confers hardness to this vulnerable region.

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Atkins, E. D. T., Dlugosz, J. & Foord, S., 1979. Electron diffraction and electron microscopy of crystalline α-chitin from the grasping spines of the marine worm Sagitta. International Journal of Biological Macromolecules, 1, 2932.
Beklemishev, K. v., 1954. Demonstration of silica parts in the integument of the lower crustaceans. Doklady¯ Akademii nauk SSSR, 97, 543545.
Bryan, G. W. & Gibbs, P. E., 1979. Zinc – a major inorganic component of nereid polychaete jaws. Journal of the Marine Biological Association of the United Kingdom, 59, 969973.
Dilly, P. N. & Nixon, M., 1976. The cells that secrete the beaks in octopus and squids (Mollusca, Cephalopoda). Cell and Tissue Research, 167, 229241.
Duvert, M. & Gros, D., 1982. Further studies on the junctional complex in the intestine of Sagitta setosa. Cell and Tissue Research, 225, 663671.
Furnestin, M.-L., 1982. Dents et organe vestibulaire des Chaetognathes au microsope électronique à balayage. Relations taxonomiques, écologiques et biologiques. Revue zoologique africaine, 96, 138173.
George, J. D. & Southward, E. C., 1973. A comparative study of the setae of Pogonophora and polychaetous Annelida. Journal of the Marine Biological Association of the United Kingdom, 53, 403424.
Hillerton, J. E. & Vincent, J. F. V., 1982. The specific location of zinc in insect mandibles. Journal of Experimental Biology, 101, 333336.
Kuhl, W., 1938. Chaetognatha. In Bronn's Klassen und Ordnungen des Tierreichs, ed 4. Vermes, Abteilung IV, Buch 2, Teil 1, pp. 1226. Leipzig: Akademische Verlagsgesellschaft m.g.H.
Muzzarelli, R. A. A. & Tubertini, O. 1969. Chitin and chitosan as Chromatographie supports and adsorbents for collection of metal ions from organic and aqueous solutions and seawater. Talanta, 16, 15711577.
Nagasawa, S. & Marumo, R., 1973. Structure of grasping spines of six chaetognath species observed by scanning electron microsopy. Bulletin of the Plankton Society of Japan, 19, 516.
Rudall, K. M., 1976. Molecular structure in arthropod cuticles. In The Insect Integument (ed. Hepburn, H. R.), pp. 2141. Amsterdam: Elsevier.
Schmidt, W. J., 1940. Zur morphologie, Polarisationsoptik und Chemie der Griefhaken von Sagitta hexaptera. Zeitschrift für Morphologie und Ökologie der Tiere, 37, 6382.
Simpson, T. L. & Volcani, B. E., 1981. Introduction. In Silicon and Siliceous Structures in Biological Systems (ed. Simpson, T. L. and Volcani, B. E.), pp. 312. Springer-Verlag.
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Journal of the Marine Biological Association of the United Kingdom
  • ISSN: 0025-3154
  • EISSN: 1469-7769
  • URL: /core/journals/journal-of-the-marine-biological-association-of-the-united-kingdom
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