The Biological Bulletin, Vol 195, Issue 2 120-125, Copyright © 1998 by Marine Biological Laboratory

ECOLOGY AND EVOLUTION

Body Polarity and Mineral Selectivity in the Demosponge Chondrosia reniformis

G. Bavestrello, U. Benatti, B. Calcinai, R. Cattaneo-Vietti, C. Cerrano, A. Favre, M. Giovine, S. Lanza, R. Pronzato and M. Sara
Instituto di Zoologia dell'Universita di Genova, Via Balbi, 5 I-16126 Genova

The skeleton of the common Mediterranean demosponge Chondrosia reniformis lacks endogenous spicules; but exogenous siliceous material is selectively incorporated into its collagenous ectosome, strengthening this layer. Nevertheless, the settling of sponge buds during asexual reproduction necessitates an active incorporation of the calcareous substratum through the sponge lower ectosome. This fact suggests the presence of a polarity in the sponge, with the lower surface selecting primarily carbonates, and the upper surface selecting exclusively silicates and quartz. Our observations under experimental conditions showed that the strong selectivity of the upper ectosome is realized only when the sponge is fixed to the substratum; if detached, the sponge incorporates both quartz and carbonates. In laboratory experiments, the incapacity of both kinds of ectosome to regenerate into a new complete sponge suggests that this polarity arises early in ontogeny.

This article has been cited by other articles:

				M. W. Taylor, R. Radax, D. Steger, and M. Wagner Sponge-Associated Microorganisms: Evolution, Ecology, and Biotechnological Potential Microbiol. Mol. Biol. Rev., June 1, 2007; 71(2): 295 - 347. [Abstract] [Full Text] [PDF]

				B. M. Degnan, S. P. Leys, and C. Larroux Sponge Development and Antiquity of Animal Pattern Formation Integr. Comp. Biol., April 1, 2005; 45(2): 335 - 341. [Abstract] [Full Text] [PDF]