Have you ever wondered if and how sea shells are broken down in nature? Other than simply wearing down from being jostled about by wave energy, there are a host of organisms that specialize on various fungi and a variety of invertebrate animals.
Some larger animals, such as drum and stone crabs, crush mollusks during their routine feeding activity. Even more intriguing and much less known are a myriad of small creatures that bore into the shells, thus weakening the walls and often providing habitat for a new wave of invaders. The blister worm (Polydora) etches a groove in the shell that eventually becomes a deep pit where the worm lives. The boring sponge (Cliona) produces a network of tunnels which, if extensive enough, cause the shell’s walls to collapse. A species that specializes in oyster shells is the oyster piddock (Diplothyra smythii). This critter is a boring clam that might bore completely through the oyster!
The next time you’re at the beach, examine shells closely and you may find evidence of shell recycling.