Atlantic Sea Swallow

Glaucus atlanticus

Nudibranchs

Usual depth0 m
Water temperature17–29 °C
Best monthsJanuary, February, and March
How commonOccasional

All species

Photo credit: (c) Sylke Rohrlach, some rights reserved (CC BY-SA) · CC BY-SA · iNaturalist

About this species

Glaucus atlanticus is a species of sea slug in the family Glaucidae.

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

Where and when

Where it has been recorded

Worldwide

Loading the map

Best months

Worldwide (open data)

January: 221 records
February: 208 records
March: 265 records
April: 143 records
May: 67 records
June: 30 records
July: 37 records
August: 64 records
September: 88 records
October: 79 records
November: 78 records
December: 162 records

Depth and water temperature

Depth

Mostly recorded at 0 m · Deepest record: 266.1 m

0–10 m: 21 records
10–20 m: 0 records
20–30 m: 0 records
30–40 m: 0 records
40–50 m: 0 records
50–60 m: 0 records
60–70 m: 0 records
70–80 m: 0 records
80–90 m: 0 records
90–100 m: 0 records
100–110 m: 0 records
110+ m: 1 records

Water temperature

Recorded in surface water of 17–29 °C

16–18 °C: 7 records
18–20 °C: 5 records
20–22 °C: 7 records
22–24 °C: 14 records
24–26 °C: 2 records
26–28 °C: 8 records
28–30 °C: 2 records

Photos

(c) jumanbar, some rights reserved (CC BY-SA) · CC BY-SA · iNaturalist
(c) Thomas Mesaglio, some rights reserved (CC BY) · CC BY · iNaturalist
(c) eklemp, some rights reserved (CC BY) · CC BY · iNaturalist
(c) SiphonophoreSlinger, some rights reserved (CC BY) · CC BY · iNaturalist
(c) harrier, some rights reserved (CC BY) · CC BY · iNaturalist
(c) harrier, some rights reserved (CC BY) · CC BY · iNaturalist
no rights reserved · CC0 1.0 · iNaturalist

Names and classification

English: Atlantic Sea Swallow, Purple ocean slug, Sea swallow, purple ocean slug, sea swallow

Names in 1 more languages

Japanese: アオミノウミウシ

Other scientific names: Doris radiata, Glaucus distichoicus, Glaucus flagellum, Glaucus hexapterigius, Glaucus lineatus, Glaucus longicirrhus, Glaucus radiatus

Similar species

Glaucilla marginata

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.
57 open-data records from 1949 to 2025.

Log what you see on your next dive

The free DiveHive diver app keeps your logbook with every sighting and shows what lives at the site you dive next.

Join the waitlist