Yellow Encrusting Sponge

Aplysina aerophoba

The yellow encrusting sponge (Aplysina aerophoba) is a conspicuous marine sponge found throughout the Mediterranean Sea and eastern Atlantic. It forms bright yellow tubular or encrusting colonies on rocky substrates, typically with chimney-like oscula (exhaust openings) at the tops of tubes. Colonies can cover substantial areas of rock face and grow up to 20 cm tall. The vivid yellow color turns dark purple-black when the sponge is removed from water and exposed to air. It is a filter feeder processing large volumes of seawater to extract bacteria and organic particles. This sponge contains bioactive compounds of pharmaceutical interest and provides habitat for numerous small invertebrates within its porous structure.