Two Distinct Populations of Collagen Fibrils in A “Sclerosponge” (Porifera)

Abstract

An assemblage of “Coralline sponges” has been discovered recently in the Phylum Porifera. These sponges contain, in addition to their discrete calcareous or siliceous spicules, a massive calcareous skeleton which offers some analogies with the skeleton of the mineralized cnidarians. “Coralline sponges” are classified either among several groups of sponges (Vacelet, 1983) or as a new class, the Sclerospongiae (Hartman and Goreau, 1970; Termier and Termier, 1973); they are considered as the survivors of organisms which contributed to reef building during the Mesozoic and Paleozoic Eras. The comparison of the collagen of these “living fossils” with the collagen of modern sponges, as well as with the collagen of other animals could yield interesting data on the evolutionary aspects of this protein and of the Phylum Porifera.