Naked sea butterfly
Amazing fact
The naked sea butterfly has a substance in its body that fish avoid.
東京大学大気海洋研究所 国際沿岸海洋研究センター
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An illustration based on the real animal.
A little discovery to share.
The naked sea butterfly has a substance in its body that fish avoid.
THE REAL WORLD
The real Naked sea butterfly
- Scientific name
- Clione elegantissima
- Japanese name
- ハダカカメガイ（クリオネ）
- Group
- Ocean animals
- Class
- Gastropoda
- Order
- Pteropoda
- Family
- Clionidae
- Genus
- Clione
This page covers the Clione found around Hokkaido, distinct from the Atlantic species Clione limacina.
How the Naked sea butterfly lives
Along the Sea of Okhotsk coast, it appears when drift ice reaches the shore. It is believed to eat only the sea snail called mijin-uki-maimai. It stores a lot of an unusual oil called ether lipid in its body.
東京大学大気海洋研究所 国際沿岸海洋研究センターBasic data
- Size
- Body length: 1–2 cm
- Range
- Off Shiretoko, Hokkaido
Where the Naked sea butterfly has been recorded
Records: GBIF.org (CC0 and CC BY 4.0 records, retrieved 2026-11-07). Map: Natural EarthSee the records on GBIF
Watch wild animals from a distance. Do not touch or feed them, and take care of the places where they live.
Names around the world
Names come from Wikidata and iNaturalist records. Where a language has no recorded name, we use the scientific name.
Sources and how we check
- アクアマリンふくしま — ハダカカメガイ（クリオネ）Checked: 2026-11-03
- 鳥羽水族館 — ハダカカメガイ（クリオネ）Checked: 2026-11-04
- 東京大学大気海洋研究所 国際沿岸海洋研究センター — クリオネChecked: 2026-11-06
We check each fact against its source. The illustrations simplify how the real animal looks.
The classification (class, order, family, genus) follows Wikidata records, checked against GBIF. Classifications can change as research goes on.
The basic data are the values given in each source. They vary with how the animal is measured, whether it is male or female, and whether it lives in the wild or in captivity.
This page was translated from the original Japanese with the help of AI.
Report a mistakeWhen you meet the Naked sea butterfly, look for this
- Look for the digestive gland and other parts showing red through its body.
- You may see it extend projections called buccal cones while feeding.
Animals do different things from day to day, so you may not always see this.
鳥羽水族館EXHIBIT INFORMATION
Places that keep or show the Naked sea butterfly
Zoos, aquariums and other places whose official websites say they keep or show this animal.
Tohoku
Chubu
- 越前松島水族館展示休止の後、2026年2月に展示再開の告知（こんぺいとうハウス）
Kinki
- Toba Aquarium公式の生きもの図鑑に掲載（展示時期の記載なし）
- Osaka Aquarium Kaiyukan2026年8月2日から北極圏で採集した個体を「北極圏」エリアで展示。展示期間・数は生物の状況により予告なく変更あり
Displays can change with the animals’ health and the seasons. Check each facility’s official website before you go.
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