An overview of the Mediterranean cave-dwelling horny sponges (Porifera, Demospongiae) Author Manconi, Renata Author Cadeddu, Barbara Author Ledda, Fabio Author Pronzato, Roberto text ZooKeys 2013 281 1 68 http://dx.doi.org/10.3897/zookeys.281.4171 journal article http://dx.doi.org/10.3897/zookeys.281.4171 1313-2970-281-1 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, Tremies 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 ; Marti et al. 2004 ; Turon et al. 2009 ; Pronzato and Manconi 2011 ). Figure 25 Hippospongia communis . a a large, over 25 cm, specimen collected along the Libyan coast b, c skeletal network with tips of primary cored fibres supporting conules at the sponge surface d ascending tracts of primary fibres in the choanosome.