1.
a mollusk with two hinged shells that close around a soft body, such as a clam, oyster, scallop, or mussel; a bivalve, bivalved shellfish
The Japanese cover term for the biological class Bivalvia — mollusks whose bodies are enclosed by two hinged shells that can open and shut. The name is literally 'two-sheet shellfish,' counting each valve as a thin flat 'sheet.' Common members in Japanese cuisine include あさり} (Manila clam), {しじみ} (freshwater clam), {ほたて} (scallop), {はまぐり} (hard clam), and {カキ (oyster). 二枚貝 is contrasted with 巻き貝 (univalves, snails with a single spiral shell).
アサリは二枚貝の一種だ。
The asari clam is a kind of bivalve.
二枚貝は砂抜きをしてから調理する。
Bivalves are cooked after you have them spit out their sand.
二枚貝は海水をろ過して栄養を取り込む。
Bivalves filter seawater to take in nutrients.
ホタテやカキなど、日本人の食卓になじみの深い二枚貝は数多く存在する。
There are many bivalves that are familiar on Japanese tables, such as scallops and oysters.
Composed of 二枚 ('two sheets / two flat objects,' using the counter 枚 for thin, flat things) + 貝 (shellfish). The two halves of a bivalve's shell are counted as flat 'sheets,' giving the word its literal meaning 'two-sheet shellfish.' When 貝 appears as the second element of a compound, it is read {がい} (rendaku).
COMMON COLLOCATIONS:
- 二枚貝類: bivalves (as a biological group)
- 二枚貝の仲間: members of the bivalve family
- 二枚貝の砂抜き: removing sand from bivalves (before cooking)
- 二枚貝の養殖: bivalve farming / aquaculture
- 二枚貝の殻: a bivalve shell
COMMON 二枚貝:
- アサリ (浅蜊): Manila clam — small, most common in miso soup and pasta.
- シジミ (蜆): freshwater basket clam — very small, used in miso soup.
- ハマグリ (蛤): hard clam — larger, traditional in ひな祭り soup.
- ホタテ(ガイ) (帆立貝): scallop — prized for its large adductor muscle.
- カキ (牡蠣): oyster — eaten raw or cooked; a major aquaculture product.
- ムール貝: mussel — loanword + 貝.
SIMILAR WORDS:
- 巻き貝: univalve, snail, gastropod — shellfish with a single spiral shell; the main biological counterpart of 二枚貝.
- 貝 / 貝類: shellfish (in general) — the broader cover term including both bivalves and univalves.
- 甲殻類: crustaceans — a separate group including shrimp, crabs, and lobsters; not shellfish in the biological sense, but often grouped with them culinarily.
BIOLOGY NOTE:
Bivalves are filter feeders that pump water through gills to extract plankton and organic particles, which makes them sensitive indicators of water pollution. They can also accumulate toxins from harmful algal blooms, which is why shellfish advisories warn specifically about 二枚貝.