Flat-bottomed star

About this species

Asterias amurensis, also known as the Northern Pacific seastar and Japanese common starfish, is a seastar found in shallow seas and estuaries, native to the coasts of northern China, Korea, far eastern Russia, Japan, Alaska, the Aleutian Islands and British Columbia in Canada. Two forms are recognised: the nominate and forma robusta from the Strait of Tartary. It mostly preys on large bivalve molluscs, and it is mostly preyed on by other species of starfish. Population booms in Japan can affect the harvest of mariculture operations and are costly to combat.

Text from the Wikipedia article “Asterias amurensis”, 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: 96 records
February: 101 records
March: 86 records
April: 108 records
May: 216 records
June: 275 records
July: 368 records
August: 261 records
September: 199 records
October: 128 records
November: 64 records
December: 60 records

Depth and water temperature

Depth

Mostly recorded at 15–85 m · Deepest record: 530 m

0–10 m: 20 records
10–20 m: 31 records
20–30 m: 66 records
30–40 m: 38 records
40–50 m: 21 records
50–60 m: 20 records
60–70 m: 8 records
70–80 m: 13 records
80–90 m: 6 records
90–100 m: 5 records
100–110 m: 5 records
110+ m: 10 records

Water temperature

Recorded in surface water of 0–24 °C

0–2 °C: 31 records
2–4 °C: 32 records
4–6 °C: 51 records
6–8 °C: 9 records
8–10 °C: 0 records
10–12 °C: 0 records
12–14 °C: 9 records
14–16 °C: 13 records
16–18 °C: 3 records
18–20 °C: 48 records
20–22 °C: 0 records
22–24 °C: 1 records
24–26 °C: 1 records

Photos

(c) Kim, Hyun-tae, some rights reserved (CC BY), uploaded by Kim, Hyun-tae · CC BY · iNaturalist
(c) Photographer: Julian Finn, some rights reserved (CC BY) · CC BY · iNaturalist
(c) MickWH, some rights reserved (CC BY) · CC BY · iNaturalist
(c) Erin McKittrick, some rights reserved (CC BY) · CC BY · iNaturalist
(c) ttsquid, some rights reserved (CC BY) · CC BY · iNaturalist
(c) Matt Muir, some rights reserved (CC BY) · CC BY · iNaturalist
(c) ttsquid, some rights reserved (CC BY) · CC BY · iNaturalist

Names and classification

English: Flat-bottomed star, Japanese common starfish, Northern Pacific seastar, Purple-orange star, Japanese Common Sea Star, North Pacific Starfish

Names in 5 more languages

German: Nordpazifischer Seestern
Spanish: Estrella de mar japonesa
French: Étoile de mer du Pacifique Nord
Japanese: キヒトデ, マヒトデ
Korean: 아무르불가사리, 아므르불가사리

Other scientific names: Allasterias migrata, Asterias acervispinis, Asterias flabellifera, Asterias gracilispinis, Asterias latissima, Asterias pectinata, Parasterias albertensis

Similar species

Eleven-armed seastar
Coscinasterias muricata
Seven-armed Sea Star
Astrostole scabra
Island Sea Star
Astrostole rodolphi
Coscinasterias acutispina
Coscinasterias calamaria
Anasterias mawsoni

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).
905 open-data records from 1884 to 2024.
Species data updated October 31, 2026.