Portunus armatus
Scientific classification Edit this classification
Domain: Eukaryota
Kingdom: Animalia
Phylum: Arthropoda
Class: Malacostraca
Order: Decapoda
Suborder: Pleocyemata
Infraorder: Brachyura
Family: Portunidae
Genus: Portunus
Species:
P. armatus
Binomial name
Portunus armatus
(A. Milne-Edwards, 1861)

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]

References

  1. ^ a b c d e Lai, Joelle C Y; Ng, Peter K L; Davie, Peter J F (2010). "A revision of the Portunus pelagicus (Linnaeus, 1758) species complex (Crustacea: Brachyura: Portunidae), with the recognition of four species". The Raffles Bulletin of Zoology. 58 (2): 199–237.
  2. ^ a b c d "Blue Swimmer Crabs". Government of Western Australia. Department of Primary Industries and Regional Development. 2021. Retrieved 2022-12-29.
  3. ^ a b "Blue Swimmer Crab". Australian Museum. 2020. Retrieved 2022-12-29.
  4. ^ a b c d Johnston, D.; Yeoh, D.; Harris, D.; Fisher, E. (2020). "Blue Swimmer Crab (Portunus armatus) Resource in the West Coast Bioregion, Western Australia Part 1: Peel-Harvey Estuary, Cockburn Sound and Swan-Canning Estuary" (PDF). Government of Western Australia. Department of Primary Industries and Regional Development. Retrieved 2022-12-27.
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