AS-16 LIVING SHELL COMMUNITY

Dead oyster and clam shells are of great ecological significance on sandy bottoms where they provide a substrate for an entire community of sessile animals and plants, which either encrust or bore directly into the dead shells. By distributing one or more shells to each student, observations can be made concerning the various adaptations common to this specialized lifestyle. Some shells are covered with barnacles, others have pink and red Astrangia coral or orange bryozoans; and still others support tunicates. Sabellarid and serpulid polychaetes encrust the surface with their limestone or sandy tubes. Feather duster worms expand their crowns from within the shell. Limpets and chitons move about on the surface grazing on algae, and some shells have orange dorid nudibranchs, Doriopsilla pharpa. The juvenile stages of the boring sponge, Cliona celata, riddle the shells, dissolving away the limestone substrate. These are not just specimens; they are entire living mini-habitats.