Blue Swimmer Crab

Portunus armatus

Portunus armatus - Blue Swimmer Crab
image_search Terms and anatomy

Size: 20 cm

Distribution: All SA coastal and gulf waters west of Cape Jervis

Habitat: Sandy areas and seagrass/algae beds

Depth: Subtidal to 10+ metres

Portunus armatus - Blue Swimmer Crab
Portunus armatus - Blue Swimmer Crab

A highly-sought after commercial species, the Blue Swimmer crab is most often found in seagrass or algae, but can also be present in sandy or silty areas. A strong swimmer, this species has distinctive rear paddles and long claws, which it extends when threatened to appear larger. Its colour ranges from brown-green, through to electric blue in adult males, with white spots on the legs. It also has a distinctive carapace, shaped like an axe-head, with large spines on each side and an almost serrated front edge. This crab is most similar to the invasive Asian Paddle Crab (Charybdis japonica), which is not yet established in Australia, but P. armatus can be distinguished by the large spines on the carapace, blue colouration and more slender claws.