{{Short description|Species of crustacean}} {{Speciesbox | genus = Portunus | species = armatus | image = Blue Crab from Banate Bay CIMG0015.jpg | authority = (A. Milne-Edwards, 1861) }}
'''''Portunus armatus''''' (also known as '''''Neptunus armatus''''') is a species of crustacean, a swimming crab in the family Portunidae found in Australia and eastwards to New Caledonia.<ref name=Lai/> Common names include '''blue swimmer crabs''', '''Blue manna''', '''Blueys,'''<ref name=FishWA/> and '''Jennies''' (for females).<ref name=AusMuseum/> The species was originally considered as a geographic variation of Portunus pelagicus, however in 2010 the Portunus pelagicus species was reviewed using DNA, as well as physical characteristics including measurements and four species recognised: Portunus pelagicus, Portunus armatus, Portunus reticulatis and Portunus segnis. The range of Portunus armatus overlaps with Portunus pelagicus in the Northern Territory of Australia.<ref name=Lai/>
Portunus armatus is a commercially and recreationally important fishing crab. Although it is resilient to overfishing, collapse of populations have occurred in some areas where there has been adverse environmental conditions and heavy fishing.<ref name=DPIRD/>
These crabs inhabit waters from 50 m depth through to the intertidal zone, moving from shallower to deeper water in winter. Individuals in estuaries will move to the ocean in response to fresh water from winter rains.<ref name=DPIRD/> They prefer areas with flat muddy or sandy bottoms with seagrass or algae.<ref name=Lai/> They reach maturity in one year,<ref name=AusMuseum/> and live to an age of 2-3 years.<ref name=DPIRD/> Maximum size across the carapace is around 200mm<ref name=Lai/> to 250mm,<ref name=FishWA/> with up to 800mm maximum claw span.<ref name=FishWA/>
The color is variable, but the carapace of males is generally dark blue-green with spots overall and bands at the front, whereas females are similarly pattered but brownish and with the tips of the claws deep brownish red.<ref name=Lai/> Behind the eye on each side of the carapace, is a total of 9 teeth or spines, including one long spine at the side.<ref name=DPIRD/> The last limb ends in a flat paddle.
Diet is mostly small fish and other crustaceans, molluscs, worms, and less so algae and seagrass.<ref name=FishWA/>
== References ==
<references>
<ref name=Lai>{{Cite journal|last1=Lai|first1=Joelle C Y|last2=Ng|first2=Peter K L|last3=Davie|first3=Peter J F|date=2010|title=A revision of the Portunus pelagicus (Linnaeus, 1758) species complex (Crustacea: Brachyura: Portunidae), with the recognition of four species|url=https://www.researchgate.net/publication/228663959|journal=The Raffles Bulletin of Zoology|volume=58 |issue=2|pages=199–237}}</ref>
<ref name=FishWA>{{cite web | date=2021 | title=Blue Swimmer Crabs | url=https://www.fish.wa.gov.au/species/blue-swimmer-crabs/pages/default.aspx | website = Government of Western Australia | publisher=Department of Primary Industries and Regional Development | access-date=2022-12-29}}</ref>
<ref name=AusMuseum> {{cite web | date=2020 | url=https://australian.museum/learn/animals/crustaceans/blue-swimmer-crab |title=Blue Swimmer Crab |publisher= Australian Museum | access-date=2022-12-29}}</ref>
<ref name=DPIRD>{{cite web |date=2020|title=Blue Swimmer Crab (Portunus armatus) Resource in the West Coast Bioregion, Western Australia Part 1: Peel-Harvey Estuary, Cockburn Sound and Swan-Canning Estuary |last1=Johnston|first1=D.|last2=Yeoh|first2=D.|last3=Harris|first3=D.|last4=Fisher|first4=E.|url=https://www.fish.wa.gov.au/Documents/research_reports/frr307.pdf |access-date=2022-12-27 |website=Government of Western Australia |publisher=Department of Primary Industries and Regional Development}}</ref>
</references>
{{Portal|Crustaceans}} {{Taxonbar|from=Q14159710}}
Category:Portunoidea Category:Crabs of the Pacific Ocean