As pelagic larvae, harlequin shrimp have completely different physiological characteristics than as adults and once they metamorphose into adults, that changes and they are no longer capable of eating what they ate as larvae. Biota is not culturing harlequin shrimp but there is at least one person doing so in the USA and their offspring are available from Quality Marine. No one has ever been able to get harlequin shrimp to exist long term on a non-starfish diet. I've read of several attempts to do so, and none ended up working. Aside from starfish, harlequin shrimp can resort to eating the tube feet of sea urchins (another echinoderm), however, this only happens if they are starving.
