California Boring Sponge

Cliona californiana

The California Boring Sponge, known scientifically as Cliona californiana, is a species of demosponge found in the north-eastern Pacific Ocean, from Alaska to Baja California. It is commonly seen in colder waters and inhabits both subtidal and intertidal zones, often at depths of up to 120 meters. Divers might spot this sponge as small yellow patches on the shells of bivalve molluscs, where it bores into the shell valves. The visible parts of the sponge are typically no more than 3 mm in diameter and may contain small openings called oscula. This sponge is known for its unique boring behavior, where it secretes acid to dissolve the shells of its hosts, such as scallops and oysters, making it a pest to shellfish farmers. As it grows, it can spread across the shell surface and eventually become free-living, reaching a length of up to 9 cm and a height of 6.5 cm. The California Boring Sponge is preyed upon by the nudibranch Doriopsilla albopunctata. In terms of reproduction, members of its class, Demospongiae, are hermaphroditic, and their life cycle includes a free-swimming larval stage before settling on a substrate. Despite its impact on shellfish, the sponge poses no threat to humans and has not been evaluated for conservation status.