I dont believe that. Ive researched them and adult horseshoe crabs eat clams,worms, and other small inverts. I dont believe they need alot of sand to sift through because public keep them without much sand and keep them alive for years. Dont get me wrong I do think the more sand the better. Mine eats clams,shrimp, and mussels. He/she unburies itself when its hungry I feed it and I dont see it for about a week. Its going on 7 months in my tank.