Hippospongia communis (Lamarck, 1813) Fig. 25

Spongia communis Lamarck, 1813: 370.

Description.

Growth form massive, rounded. Colour in vivo dark grey. Surface with large, sparse conules. Oscules scattered or grouped at the top surface, pre-oscular cavities extremely developed, large subdermal canals radially arranged at oscula. Large cavernous cavities (1-4 cm) irregularly scattered in the choanosome. Skeleton reticulate with ascending main fibres supporting the conules. Primaries (60-100 µm in diameter) twisted, with inclusions (fragments of spicules and mineral granules). Primaries present exclusively as main axis of conules, towards the surface, in some specimens/populations. Secondaries (20-30 µm in diameter) abundant, forming a dense network, without inclusions.

Habitat.

Cave, coralligenous community, Posidonia oceanica meadow, rocky/detritic/muddy bottom. Bathymetric range 1-200 m.

Mediterranean caves.

Blava, Blue, La Catedral caves (Balearic Sea); Endoume, Figuier, Trèmies caves (Gulf of Lions); Azzurra, Mago caves (Central Tyrrhenian Sea) (Pouliquen 1972; Pulitzer-Finali and Pronzato 1976, 1980; Cinelli et al. 1977; Pansini et al. 1977; Pulitzer-Finali 1977; Bibiloni et al. 1989; Martì et al. 2004; Turon et al. 2009; Pronzato and Manconi 2011).