noun
Refers specifically to the Japanese scallop (Patinopecten yessoensis), also known as ホタテガイ.
See also: ホタテガイ
オウギガイは北海道でよく獲れる。
Japanese scallops are often caught in Hokkaido.
noun
Refers to the giant clam (Tridacna gigas), also known as シャコガイ. This usage is less common and may be considered a misapplication or regional variant.
See also: シャコガイ
沖縄の海ではオウギガイが見られることもある。
Giant clams can sometimes be seen in the seas of Okinawa.
ホタテガイ is the more common name for the Japanese scallop; オウギガイ is a less frequent synonym.
シャコガイ is the standard name for the giant clam; オウギガイ is rarely used for this meaning.
Compound of 扇 (おうぎ, 'folding fan') + 貝 (かい, 'shellfish'), referring to the fan-like shape of the scallop shell. The extension to giant clam may be due to similar shell shape.