Marine Biology

Rock Borers

Rocks, especially limestone rocks in the intertidal regions, down to depths of 30-40 metres, are bored or riddled with holes and tubes of marine invertebrates. Boring is performed either by mechanical or by chemical means. Animals that bore into rocks include sponges, polychaetes, sea urchins and mollusks.

Sponges:

Sponges of the families Clionidae and Spirastrellidae bore into limestone rocks by chemical means. They make holes by producing CO₂ liberated at the surface of contact with the consequent solution of CaCO₃. Thus, Cliona bores into sand-stone, submerged structures made of calcareous material and oyster shells and producing a series of branching passages which open at frequent intervals to the surface.