Sea slug (Urido) - Urido (English spelling) sea slug

Japanese: ウミウシ(海牛) - ウミウシ（英語表記）sea slug

A general term for shellless Opisthobranchia species of the Gastropoda class of the Mollusca phylum. Many species have a slug-like, elongated body, covered with a mantle. They have a pair of antennae on their head, but some have another pair of head tentacles in front of them. Their body surfaces range from smooth (such as the blue sea slug) to those with many gill projections on their backs (such as the minnow sea slug), and many species are beautifully colored. Some species have an anus on their backs and a row of secondary gills around it (white sea slugs), while others have gills on both sides of their backs (minnow sea slugs). They are hermaphrodites, with the reproductive opening located at the front right side. Many live on rocky reefs on the seafloor, crawling with their wide, flat feet, but the odontocephalus and blue sea slugs live a planktonic life. Some sea slugs, such as the glow-in-the-dark sea slug, flower-shaped sea slug, and cone-shaped sea slug, glow in the dark. The light blue sea slug feeds on cnidarians and protects itself by storing the nematocysts in the projections on its back. The blue light blue sea slug feeds on floating morning glory shells and other sea slugs. The large, hood-like mouth of the meribe sea slug is used to cover rocks and eat small crustaceans it catches. Most egg masses are string-like, and are laid in a ribbon-like shape with one long side attached to the rock.

Source: Encyclopaedia Britannica Concise Encyclopedia About Encyclopaedia Britannica Concise Encyclopedia Information

Japanese:

軟体動物門腹足綱の後鰓類 Opisthobranchiaに属する種類のうち，殻を欠いたものの総称。体はナメクジ状に細長い種類が多く，体表は外套でおおわれる。頭には1対の触角があるが，その前方にもう1対の頭触手を有するものもある。体表はなめらかな種 (アオウミウシなど) から背上に多くの鰓突起を有する種 (ミノウミウシなど) まであり，美しい色彩の種が多い。背面に肛門があってその周囲に二次的にできた鰓が並ぶ種 (シロウミウシ) や，鰓が背の左右に並ぶ種 (ミノウミウシ) がある。雌雄同体で，生殖口は右側前方にある。多くは海底の岩礁上にすみ，広い平らな足ではうが，コノハウミウシやアオミノウミウシは浮遊生活をする。ヒカリウミウシ，ハナデンシャ，コノハウミウシなどは発光する。ミノウミウシは刺胞動物を食べ，その刺胞を背上の突起の中にたくわえ身を守る。アオミノウミウシは浮遊性のアサガオガイなどを食べる。また，メリベウミウシの口は頭巾状で大きく，これを岩上にかぶせ，それで捕えた小さい甲殻類を食べる。卵塊は多くは紐状で，その長い一辺を岩上につけて巻いたリボン状に産む。

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