T-bar Swallowtail

About this species

Chelidonura hirundinina is a species of small and colorful aglajid sea slug, a shell-less opisthobranch gastropod mollusk in the family Aglajidae.

Text from the Wikipedia article “Chelidonura hirundinina”, licensed CC BY-SA 4.0. Read the article

Where and when

Where it has been recorded

Worldwide

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Best months

Worldwide (open data)

January: 107 records
February: 145 records
March: 163 records
April: 163 records
May: 139 records
June: 113 records
July: 87 records
August: 114 records
September: 133 records
October: 103 records
November: 80 records
December: 95 records

Depth and water temperature

Depth

Mostly recorded at 1–15 m · Deepest record: 52 m

0–10 m: 104 records
10–20 m: 44 records
20–30 m: 3 records
30–40 m: 0 records
40–50 m: 0 records
50–60 m: 1 records

Water temperature

Recorded in surface water of 19–29 °C

18–20 °C: 7 records
20–22 °C: 20 records
22–24 °C: 17 records
24–26 °C: 29 records
26–28 °C: 44 records
28–30 °C: 63 records

Photos

(c) Pauline Walsh Jacobson, some rights reserved (CC BY) · CC BY · iNaturalist
(c) Pauline Walsh Jacobson, some rights reserved (CC BY) · CC BY · iNaturalist
(c) Thomas Irvine, some rights reserved (CC BY) · CC BY · iNaturalist
(c) Cricket Raspet, some rights reserved (CC BY) · CC BY · iNaturalist
(c) Dan Schofield, some rights reserved (CC BY) · CC BY · iNaturalist
(c) Susan Prior, some rights reserved (CC BY) · CC BY · iNaturalist

Names and classification

English: T-bar Swallowtail, Leech Aglaja, Leech Headshield Slug, swallowtail aglaja, Swallowtail Headshield Slug

Names in 4 more languages

Spanish: Nudibranquio cola de Golondrina
French: Céphalaspide-sangsue
Japanese: ニシキツバメガイ
Simplified Chinese: 燕尾海牛

Other scientific names: Bulla hirundinina, Chelidonura adamsi, Chelidonura philinopsis

Similar species

Lovely Headshield Slug
Chelidonura amoena
Beautiful Swallowtail
Philinopsis speciosa
Variable Swallowtail
Mariaglaja tsurugensis
Odontoglaja guamensis

Sources and credits

Names and taxonomy: WoRMS (CC BY 4.0) and the GBIF Backbone (CC BY 4.0). Photos: iNaturalist observers, each under the licence shown (CC0, CC BY or CC BY-SA).

Depth, temperature, months and maps: records from OBIS and GBIF under CC0 or CC BY.
Descriptions: Wikipedia, licensed CC BY-SA, each linked to its article.
Conservation status as published by GBIF (IUCN Red List).
481 open-data records from 1972 to 2026.
Species data updated October 26, 2026.