''Portunus armatus'' is a species of crustacean, a swimming crab in the family Portunidae found in

Australia Australia, officially the Commonwealth of Australia, is a Sovereign state, sovereign country comprising the mainland of the Australia (continent), Australian continent, the island of Tasmania, and numerous List of islands of Australia, sma ...

and eastwards to

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. Common names include blue swimmer crabs, Blue manna, Blueys, and Jennies (for females). 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 ''Portunus segnis'', the African blue swimming crab, is a species of crustacean, a swimming crab belonging to the family Portunidae. While native to the western Indian Ocean, it is also invasive in the Mediterranean. It is thought to have come ...

. The range of Portunus armatus overlaps with Portunus pelagicus in the

Northern Territory The Northern Territory (commonly abbreviated as NT; formally the Northern Territory of Australia) is an states and territories of Australia, Australian territory in the central and central northern regions of Australia. The Northern Territory ...

of Australia. 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. 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. They prefer areas with flat muddy or sandy bottoms with seagrass or algae. They reach maturity in one year, and live to an age of 2-3 years. Maximum size across the carapace is around 200mm to 250mm, with up to 800mm maximum claw span. 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. Behind the eye on each side of the carapace, is a total of 9 teeth or spines, including one long spine at the side. The last limb ends in a flat paddle. Diet is mostly small fish and other crustaceans, molluscs, worms, and less so algae and seagrass.

References

{{Taxonbar, from=Q14159710 Portunoidea Crustaceans of the Pacific Ocean