Why do oyster beds seem to be filled lots of little critters?

Lots of little critters are signs of a healthy flourishing ecosystem in the ocean. Just as kelp beds form a forest for many types of fish and other creatures to inhabit, oyster beds form a reef where biodiversity explodes. This is like people putting birdhouses in their yards, if you provide a home where none exists, then the birds can come and live there. We plant large numbers of oysters on beaches, which are otherwise barren; rocky spaces, almost devoid of critters. In essence, we plant a forest in the middle of a desert, and in a short space of time, we have every creature imaginable setting up home there and living quite happily. This is fine for the oysters too. Our oyster beds are quite remarkable next to some unfarmed beaches in our area where a population of sand dollars has moved through. The sand dollar beaches are beautiful sandy beaches for humans but are also desolate, lifeless places for ordinary sea creatures. The reason is that the sand dollar way of life is like ...  more