Green Boring Sponge

Cliona viridis

The Green Boring Sponge, Cliona viridis, is a demosponge known for its ability to excavate into calcareous substrates like limestone, creating channels and chambers. When growing on non-calcareous surfaces, it forms encrusting or massive structures. Its osculi, or exhalent openings, are a few millimeters wide and can be yellowish-green or light brown, often with pale rims. The sponge's color is due to the presence of zooxanthellae, which are symbiotic algae living within its tissues. This species is distributed across the eastern Atlantic, the Mediterranean Sea, and the Indo-Pacific Ocean. It typically inhabits shallow waters but can be found at depths of up to 367 meters. The sponge is most commonly seen in well-lit areas and semi-dark cave entrances, often dominating the shallow sublittoral zones. In deeper waters, it tends to grow on coralline algae. The Green Boring Sponge is a filter feeder, drawing water through its ostioles and filtering out food particles like bacteria. It is also oviparous, with internal fertilization and a planktonic larval stage. The larvae settle on the seabed and develop into juvenile sponges within about two weeks. Despite containing zooxanthellae, the sponge does not rely on photosynthesis and can grow in total darkness. This species is harmless to humans and has not been evaluated for conservation status.