Hairy Seaweed Crab

Notomithrax ursus

Crustaceans
IUCN: Not evaluated

Usual depth0–17 m
Water temperature13–20 °C
Best monthsJanuary, March, and April
How commonOccasional

All species

Photo credit: (c) Kelvin Perrie, some rights reserved (CC BY), uploaded by Kelvin Perrie · CC BY · iNaturalist

About this species

Notomithrax ursus, known as the hairy seaweed crab, is a spider crab of the family Majidae.

Text from the Wikipedia article “Notomithrax ursus”, 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: 107 records
February: 100 records
March: 109 records
April: 148 records
May: 84 records
June: 33 records
July: 25 records
August: 42 records
September: 29 records
October: 45 records
November: 41 records
December: 71 records

Depth and water temperature

Depth

Mostly recorded at 0–17 m · Deepest record: 123.5 m

0–10 m: 19 records
10–20 m: 2 records
20–30 m: 1 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 13–20 °C

12–14 °C: 7 records
14–16 °C: 50 records
16–18 °C: 15 records
18–20 °C: 3 records
20–22 °C: 1 records

Photos

(c) Kelvin Perrie, some rights reserved (CC BY), uploaded by Kelvin Perrie · CC BY · iNaturalist
(c) Lisa Bennett, some rights reserved (CC BY) · CC BY · iNaturalist
(c) Michael Berardozzi, some rights reserved (CC BY) · CC BY · iNaturalist
no rights reserved · CC0 1.0 · iNaturalist
(c) Emily Roberts, some rights reserved (CC BY) · CC BY · iNaturalist
(c) Lisa Bennett, some rights reserved (CC BY) · CC BY · iNaturalist
(c) On Lee Lau, some rights reserved (CC BY) · CC BY · iNaturalist

Names and classification

English: Hairy Seaweed Crab

Other scientific names: Cancer ursus, Paramithrax cristatus, Paramithrax Latreillei

Similar species

Small Decorator Crab
Notomithrax minor
Peron's Camouflage Crab
Notomithrax peronii
Southern spider crab
Jacquinotia edwardsii
Great spider crab
Leptomithrax gaimardii
Golden Decorator Crab
Naxia aurita
Triangle crab
Eurynolambrus australis

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).
360 open-data records from 1912 to 2025.
Species data updated November 5, 2026.

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