Spheciospongia vesparium (Lamarck, 1815)
Hadromerida, Clionaidae

Common Names: Loggerhead sponge.
Growth Form: Typically a large, massive cake or broad low barrel that may look like an automobile tire; sometimes roughly globular. Regrowing torn specimens may be strongly irregular but have characteristic color, surface and consistency. Early growth stages excavate limestone and may appear as thick encrustations or low massive mounds.
Surface: Smooth non-porous with clusters of small inhalant holes (pore sieves), but sometimes irregularly rugged.
Color: Black, charcoal or dark gray, but often largely covered with pale sediment and algal turf. Oscules usually black. Internal color the same.
Consistency: Firm, slightly compressible.
Exudate: None.
Oscules: A cluster at the top center (1-3 in small individuals); flush or indented; sometimes elevated at the apex of smaller volcano-shaped individuals; widely variable in size, and with a fine marginal membrane the same color as the sponge.
Skeletal components (Spicules, fibers): Large spicules (megascleres) are curved (sometimes sinuous) rods with 1 pointed end and 1 round swollen end (tylostyles) (250-470 μm long, 8-9 μm wide); the pointed end tapers gently (fusiform). Small spicules (microscleres) are small spiny spiral rods (spirasters, amphiasters) (8-26 μm long, 4 μm wide). No spongin fibers.
Skeletal Architecture: Spicules disorganized and in loose tracts. Megascleres are densely packed; microscleres are rare and found chiefly in the surface tissue and lining canals. No distinct surface skeleton.
Ecology: Common on hard, inshore, shallow bottoms and on seagrass beds; less common on shallow reefs. The internal canal system supports an abundant, diverse invertebrate fauna including snapping shrimps (Alpheidae), amphipods, ophiuroids, and polychaetes. Water pulses generated by snapping shrimps force small puffs of sediment out through pore sieves, perhaps contributing to canal system maintenance. At extreme low tide with flat calm conditions, the exhalant current of the shallowest sponges may disturb the sea surface.
Distribution: South Florida and throughout the Caribbean Sea from 0.5 to ~18 m.
Reference(s): Ruetzler (in Hooper & van Soest, 2002).
Similar species:

Ircinia strobilina

Geodia gibberosa