Black Finger Crab
Ozius truncatus
- Usual depth0–1 m
- Water temperature15–24 °C
- Best monthsJanuary, March, and November
- How commonOccasional
Photo credit: (c) Tony Eales, some rights reserved (CC BY-SA) · CC BY-SA · iNaturalist
About this species
Ozius truncatus, the reef crab or black finger crab is a crustacean of the family Oziidae, endemic to Australia. It is distributed across southern and south western Australia, including Western Australia, South Australia, Victoria and southern NSW. A similar species Ozius deplanatus is found in eastern Australia and New Zealand, and was historically known as Ozius truncatus. In Australia the distribution of truncatus and deplanatus overlaps. Differences between the two species include that in Ozius truncatus the epibranchial ridge is broken by a groove, and the carapace is a little wider in deplanatus. The carapace is up to nearly 60 mm across, and oval in shape, around 1.4 to 1.5 times as long as wide. Ozius truncatus lives in the intertidal zone, feeding on marine snails, limpets and other small invertebrates.
Text from the Wikipedia article “Ozius truncatus”, 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: 160 records
- February: 94 records
- March: 127 records
- April: 99 records
- May: 47 records
- June: 30 records
- July: 58 records
- August: 63 records
- September: 117 records
- October: 125 records
- November: 128 records
- December: 93 records
Depth and water temperature
Depth
Mostly recorded at 0–1 m · Deepest record: 0.5 m
Water temperature
Recorded in surface water of 15–24 °C
Photos
(c) Tim, some rights reserved (CC BY) · CC BY · iNaturalist 
(c) Ben Jobson, some rights reserved (CC BY) · CC BY · iNaturalist 
(c) Josh Nitschke, some rights reserved (CC BY) · CC BY · iNaturalist 
(c) Thomas Mesaglio, some rights reserved (CC BY) · CC BY · iNaturalist 
(c) Josh Nitschke, some rights reserved (CC BY) · CC BY · iNaturalist 
(c) Tim, some rights reserved (CC BY) · CC BY · iNaturalist 
(c) Belinda Forbes, some rights reserved (CC BY) · CC BY · iNaturalist
Names and classification
- English
- Black Finger Crab, Rock Crab
Similar species
Iron crabOzius deplanatus
Spotted-belly forceps crabOzius guttatus
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).
- 315 open-data records from 1888 to 2010.
- Species data updated November 5, 2026.
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