Skeletal, Morphology of Coral Reef Sponges: A Scanning Electron Microscope Study

Abstract

Scanning electron microscopy was used to examine the form and arrangement of skeletal components in intact specimens of four Great Barrier Reef sponges. The four sponges contain markedly different skeletal components and compositions, typical of the wide genetic diversity in the Porifera. The nature of the sponge skeleton has an influence on the habitat ranges of these sponges. Pericharax heteroraphis and Jaspis stellifera contain no spongin and occur in less turbulent areas, whereas the fibrous sponges Neofibularia irata and Ircinia wistarii occur in more turbulent regions. Different skeletal elements are used by sponges to form similar structures. In spiculated sponges, the major canals are strengthened with spicules, whereas in I. Wistarii spongin filaments perform the same role. The thickened ectosome in two sponges consists of a collagen matrix with embedded solid particles, being either spicules or incorporated foreign matter. Fibrillar collagen is an important component in binding spicules and in increasing the structural rigidity of the mesohyl.