Awabunegai - Awabunegai (English spelling) slipper shell

A gastropod shell of the family Caribagatidae in the class Gastropoda of the phylum Mollusca. It was also known as Kurusugai in the past. It is found in the western Pacific Ocean south of the Boso Peninsula and in the Indian Ocean, where it attaches to the shells of large shells such as reefs near the intertidal zone and abalone. It is elliptical, dark purple-brown in color, with a shell length of 26 mm and a shell length of about 20 mm. Unlike ordinary gastropods, it is not very bulging, and is ear-shaped. The apex of the spiral is biased toward the rear, and the shell surface is yellowish brown with a row of short spines. The opening of the shell is wide and has a thin white partition, and as its English name suggests, it is slipper-shaped and has no lid. It changes sex during its lifetime, being male when it is small and female when it becomes large. Females lay several egg sacs under their feet in a bundle, and the mother shell has the habit of protecting them and not moving.

[Takashi Okutani]

Source: Shogakukan Encyclopedia Nipponica About Encyclopedia Nipponica Information | Legend

軟体動物門腹足綱カリバガサガイ科の巻き貝。古くはクルスガイともよばれた。房総半島以南の西太平洋からインド洋にかけて分布し、潮間帯付近の岩礁やアワビなど大形貝の殻表に付着している。殻長径26ミリメートル、殻短径約20ミリメートルの楕円(だえん)形で濃紫褐色。普通の巻き貝と異なって膨らみは弱く、いわゆる耳形。螺頂(らちょう)は後方に偏り、殻表は黄褐色で短いとげ列がある。殻口は広く、薄い白色の隔壁があり、英名のようにスリッパ状で蓋(ふた)はない。一生のうちに性転換をし、小形のときは雄で、大形になると雌に変わる。雌は足の下に数個の卵嚢(らんのう)を束ねて産み付け、母貝はそれを保護して移動しない習性がある。

［奥谷喬司］

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