Infestation of Haliotis rufescens shells by a sabellid polychaete

The shell of the California red abalone ( Haliotis rufescens) can be host to a variety of organisms, including boring sponges, clams and polychaetes. These boring organisms usually do not seriously affect the growth of the abalone because they normally inhabit the outer portions of mature abalone shells. Abalone cultured in an aquaculture facility are marketed at a young age and seldom host many of these shell-dwelling organisms. Recently, however, some red abalone raised in aquaculture facilities in California have been found to be hosts to a sabellid polychaete. This polychaete infests the leading edge of the shell and can significantly interfere with the normal growth of the abalone. A cursory review of the literature does not reveal any previous cases of sabellids inhabiting the shells of abalone. This paper presents some of our observations and assumptions about this unique discovery.