Mussel Connections on a Cobble Beach

Investigating Mussel Clumps

At a cobble beach, a third-grade class watches a close-up shore video from a dry viewing path. Mussels are animals with two-part shells. Many live attached to rocks near tide pools. In the video, thin, strong threads stretch from mussel shells to the rock and to neighboring shells. After a wave passes, several mussels remain together in a clump. Waves can wash loose mussels onto dry beach stones, where they may dry out and die.

The class asks whether connections between neighbors could help mussels stay in place. Students test models, not living mussels. Step 1: They place six identical plastic rings on six marked spots on a sloping tray. Each ring represents one mussel. An equal small pad of clay holds each ring to the tray, representing attachment to a rock.

Step 2: In the unlinked setup, the rings have no connections to one another. In the linked setup, short pieces of yarn join neighboring rings. Students keep the ring type, starting spots, clay pads, and tray slope the same. Step 3: They pour one cup of cool water from the same height at the top of the tray. A large tub catches the water and loose rings.

Step 4: Students count the rings left on the sloping tray. They rebuild each setup with fresh, equal clay pads and repeat the comparison for three rounds. They return the beach materials to their bags without touching live mussels. The graph gives sample classroom results for this investigation. It counts rings remaining, not mussels surviving.