Barnacle Build-Up

An adult snail (large brown shell) and Northern rock barnacles of various ages crust a rock in the intertidal zone of Buzzards Bay. A large white barnacle is attached to the snail, two small barnacles are attached to the large one, and dozens more have settled onto the rock. Northern rock barnacles (Semibalanus balanoides) start life as free-swimming larvae that feed in coastal waters for several weeks before settling onto the substrate. WHOI ecologist Jesús Pineda, who has been studying local barnacle populations with research specialist Vicke Starczak, says the large barnacle has probably been attached to the snail for at least two years.

(Photo by Jesús Pineda, Woods Hole Oceanographic Institution)