Duck shell - Duck shell

A gastropod snail of the family Scyllidae in the class Gastropoda of the phylum Mollusca. It is a cap-shaped shell, also known as the Kikugamo or Kerigai. It is found from southern Hokkaido to all over Japan and even Taiwan. The shell's long diameter is 20 mm, its width 17 mm, and its height 13 mm. The apex of the shell is toward the front and curves somewhat like an aquiline nose, from which run two or three somewhat granular radial ribs. The periphery of the shell is slightly concave at the central side edge. The inside of the shell is white and the center is brown. They form colonies around rocky reefs where the waves splash upon them, and in winter they disperse from the colony to avoid the cold, returning to their original habitat in spring.

[Takashi Okutani]

Source: Shogakukan Encyclopedia Nipponica About Encyclopedia Nipponica Information | Legend

軟体動物門腹足綱ユキノカサガイ科の巻き貝。笠(かさ)形の貝で、別名キクガモ、またはケリガイという。北海道南部から日本全国、さらに台湾にかけて分布。殻長径20ミリメートル、殻幅17ミリメートル、殻高13ミリメートル。殻頂は前方に寄っていて、いくらか鷲鼻(わしばな)状に曲がり、そこから多少顆粒(かりゅう)状の放射肋(ろく)が2、3本ほど走る。殻の周縁は中央側縁でややへこむ。殻内は白く中央は褐色に彩られる。岩礁の波しぶきのかかるあたりにコロニーをつくり、冬は群れを解いて避寒し、春になるともとの着生場所に戻る習性がある。

［奥谷喬司］

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