Abstract We examined settlement choices of Pacific calico scallop larvae (Argopecten ventricosus = circularis, Sowerby II, 1842) on eight substrates including live black murex snails (Hexaplex nigritus = Muricanthus nigritus, Philippi, 1845), an endemic neogastropod of the Gulf of California and a common predator of A. ventricosus. We found that A. ventricosus settled on black murex snails with epibiota on their shells in higher densities (6 larvae/cm2 ± 1.0) when provided a variety of settlement substrates (P value < 0.0001). In a second experiment, we investigated factors that may contribute to settlement of A. ventricosus on black murex snails such as (1) substrate complexity of murex shells, (2) substrate complexity of murex egg cases, (3) chemical cues from murex snail mucus, and (4) presence or absence of epibiota on black murex snails. Argopecten ventricosus settled in greater densities on black murex snails with epibiota on their shells (8 larvae/cm2 ± 1.5) than other substrates (P value < 0.0001)...