sentence: Most scallops live freely.
sentences_after: However, some species attach to a substrate by a structure called a byssus. When they contract the foot, they can go deeper into the sand. A free-living scallop swims by opening and closing its shell very fast. The scallop can defend itself in this way. It protects the scallop from threatening predators.
concept_name: scallop
headings: Scallop Life habits
categories: Bivalves