Boccardia acus is a species of annelid worm from the family Spionidae.
Biology B. acus bores into the shell of Austrovenus stutchburyi (New Zealand cockle), which groves on the surface of the shell. As a result of the worm boring into the shell where the adductor muscle of A. stutchburyi attaches, it weakens the muscle and makes it difficult for the cockle to move. As a result of this, both A. stutchburyi and B. acus become more vulnerable to predation.
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