Egg predation fuels unique species associations at deep-sea hydrocarbon seeps

The large bivalve Acesta bullisi lives permanently attached around the anterior tube opening of the cold-seep tubeworm Lamellibrachia luymesi, where it uses byssal threads and an unusually formed shell to hold the aperture and plume of the tubeworm inside its inhalant mantle cavity. The nature of this association has provoked much speculation, yet it has never been fully explained. Experiments and stable isotope data strongly suggest that Acesta bullisi is oophagous, preying upon the lipid-rich eggs (zygotes) released by the host tubeworms. Moreover, virtually all mature individuals are found on female rather than male worms.