noun
bivalves
Refers to the class Bivalvia, including clams, oysters, mussels, and scallops. Used in biological and general contexts.
二枚貝類にはアサリやハマグリが含まれる。
Bivalves include clams such as the Japanese littleneck and the common orient clam.
二枚貝 is the common word for a bivalve or clam, while 二枚貝類 is the formal taxonomic term for the class Bivalvia.
Compound of 二枚 (two flat pieces) + 貝 (shellfish) + 類 (category, kind), literally 'two-shell category'. The term is a straightforward calque of the scientific concept.