Shell-burrowing Sponges of Mussels


Category 4 (Negligible Regulatory Significance in Canada)

Common, generally accepted names of the organism or disease agent

Shell-burrowing or Shell-boring sponges, Clionids.

Scientific name or taxonomic affiliation

Clionid sponges, most commonly Cliona spp.

Geographic distribution

In shells of mussels from Scandinavia and bottom-growing mussels from North America as well as other species of bivalves that live on the surface of the substrate including oysters and scallops.

Host species

Mytilus edulis.

Impact on the host

Penetrates the periostracum forming holes in the outer surface and a tunnel network throughout the shell. Severe penetration reduces the commercial value of the mussel and weakens the shell. Sponge tunnels may become inhabited by other organisms, such as polychaete worms, which can also reduce market value.

Diagnostic techniques

Gross Observations: Round holes (generally less than 2-3 mm in diameter depending on the species involved) on the surface of the shell. Inner shell surface may show the presence of dark spots or bumps, depending on the degree of penetration by the sponge.

Methods of control

Shell damage is most easily reduced or prevented by growing mussels off bottom (i.e. hanging culture).


Lauckner, G. 1983. Diseases of Mollusca: Bivalvia. In: O. Kinne (ed.) Diseases of Marine Animals. Volume II: Introduction, Bivalvia to Scaphopoda. Biologische Anstalt Helgoland, Hamburg, p. 617-626.

Rasmussen, E. 1973. Systematics and ecology of the Isefjord marine fauna (Denmark). Ophelia 1: 1-495.

Citation Information

Bower, S.M., McGladdery, S.E., Price, I.M. (1994): Synopsis of Infectious Diseases and Parasites of Commercially Exploited Shellfish: Shell-burrowing Sponges of Mussels.

Date last revised: Fall 1994
Comments to Susan Bower

Date modified: