Sand-Sifting Starfish

Astropecten polyacanthus is an Indo-Pacific sand-dwelling starfish sold as a "sand sifting starfish" for plowing the substrate, but its biology makes it a poor long-term reef fit. It is an active carnivore, not a simple detritivore — its natural diet is live sand-bed infauna: small bivalves and gastropods swallowed whole, plus worms, copepods, amphipods and even other small sea stars — and it strips that population out of a home aquarium's sand bed far faster than the tank can replenish it. Once exhausted it typically burrows out of sight and starves, often unnoticed until it decays and fouls the water; it needs a large, mature tank with a substantial, well-established sand bed. It also carries tetrodotoxin in its tissues.