Chin - Jaw

…A general term for marine fish of the Exocoetidae family, commonly known as ago in Kyushu. This species has particularly developed pectoral and pelvic fins (four-winged flying fish) or only pectoral fins (two-winged flying fish), a large lower lobe of the tail fin, a cylindrical, slender body, a short digestive tract, and a large swim bladder, making it light in weight and well-suited for flight.

*Some of the terminology that mentions "jaw" is listed below.

Source | Heibonsha World Encyclopedia 2nd Edition | Information

…ダツ目トビウオ科Exocoetidaeの海産魚の総称で，九州では一般にアゴと呼ぶ。この仲間は胸びれと腹びれ(4翼のトビウオ)，または胸びれのみ(2翼のトビウオ)がとくに発達し，尾びれの下葉も大きいほか，体が円筒形で細長く，消化管は短小で，かつ，うきぶくろが大きいために体重が軽いなど飛行に適した構造をもつ。…

※「アゴ」について言及している用語解説の一部を掲載しています。

出典｜株式会社平凡社世界大百科事典 第２版について | 情報