Tengunishi (English spelling) false fusus

A gastropod snail of the family Acanthidae in the class Gastropoda of the phylum Mollusca. It inhabits sandy bottoms at depths of 10 to 50 meters south of the Boso Peninsula. It is 19 cm high and 8.5 cm in diameter, and is spindle-shaped, somewhat thick, and robust. The spiral spire is conical and has eight stories, and the body layer occupies most of the shell, tapering downwards. There are 10 to 15 nodules on the shoulder of the body layer. Each spiral layer also usually has a strong shoulder angle and 7 to 9 slightly sharp nodules. There are also many thin spiral ribs all over the surface. The shell is pale pink, and is covered with a thick, yellowish brown, velvety shell skin. The shell opening is pale pink and long, tapering downwards to form a wide water canal groove. The outer lip forms a horn at the shoulder. The operculum is long, ovate, leathery, and blackish brown, and the nucleus is at the tapered lower end. They lay eggs in May and June, and the egg sacs are yellow, leathery, fan-shaped, and about 10 mm high, laid in rows on rocks or other surfaces. The eggs develop inside the sacs until they become juvenile shellfish, and then emerge through a small, round exit hole. The egg sacs are called sea nightshade, dyed, and sold at beaches and night stalls as toys that can be played with the mouth. The shells are used in shell crafts, and the meat is edible.

[Takashi Okutani]

Source: Shogakukan Encyclopedia Nipponica About Encyclopedia Nipponica Information | Legend

軟体動物門腹足綱テングニシ科の巻き貝。房総半島以南の水深10～50メートルの砂底にすむ。殻高19センチメートル、殻径8.5センチメートルに達し、殻は紡錘形でやや厚質堅固である。螺塔(らとう)は円錐(えんすい)形で8階、体層は殻全体の大部分を占め、下方へ細く狭くなる。体層の肩角の結節瘤(りゅう)は10～15ある。各螺層も普通は強い肩角があって、7～9の多少とがった結節瘤をもつ。また、全面に多数の細い螺肋(らろく)がある。殻は淡紅色で、表面に黄褐色のビロード状の厚い殻皮をかぶる。殻口は淡紅色で長く、下方へ細まり広く開いた水管溝となる。外唇は肩部で角をつくる。蓋(ふた)は長卵形の革質で黒褐色、核は細まった下端にある。5～6月に産卵し、卵嚢(らんのう)は黄色い革質の軍配形、高さ約10ミリメートルで、列状に並べて岩などに産み付けられる。卵はこの中で幼貝になるまで育ち、小さく丸い脱出口からはい出る。卵嚢はウミホオズキとよばれ染色されて、口で鳴らす玩具(がんぐ)として海水浴場や夜店などで売られている。殻は貝細工に利用され、肉は食用になる。

［奥谷喬司］

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