Portunus armatus | |
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Scientific classification | |
Domain: | Eukaryota |
Kingdom: | Animalia |
Phylum: | Arthropoda |
Class: | Malacostraca |
Order: | Decapoda |
Suborder: | Pleocyemata |
Infraorder: | Brachyura |
Family: | Portunidae |
Genus: | Portunus |
Species: | P. armatus
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Binomial name | |
Portunus armatus (A. Milne-Edwards, 1861)
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Portunus armatus is a species of crustacean, a swimming crab in the family Portunidae found in Australia and eastwards to New Caledonia. [1] Common names include blue swimmer crabs, Blue manna, Blueys, [2] and Jennies (for females). [3] 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. [1]
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. [4]
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. [4] They prefer areas with flat muddy or sandy bottoms with seagrass or algae. [1] They reach maturity in one year, [3] and live to an age of 2-3 years. [4] Maximum size across the carapace is around 200mm [1] to 250mm, [2] with up to 800mm maximum claw span. [2]
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. [1] Behind the eye on each side of the carapace, is a total of 9 teeth or spines, including one long spine at the side. [4] The last limb ends in a flat paddle.
Diet is mostly small fish and other crustaceans, molluscs, worms, and less so algae and seagrass. [2]