[1] A frequent inhabitant of the intertidal zone also seen attached to wharf piles, it is among the larger sea-stars found in New Zealand.

Adults often prey on mussels, forcing the shells open by applying pressure for long periods with the tube feet.

With a diameter of up to 350mm in subtidal forms, the colouration of A. scabra varies from orange through dark red to brown, or light blue to grey.

The dorsal surface is covered in speckled plates, from the center of which protrude one or two short, stubby white spines which are specialised ossicles.

Intertidal individuals are generally smaller with thicker dermal plates, allowing them greater protection when being tossed about by waves.

[8] Highest feeding frequencies are shown in individuals in the radius range of 10-29mm, with peaks of activity in the months of May and June.

This change in diet is vital to survival and longevity because it results in little to no competition between individuals of different sizes, and may be a considerable factor in the ecological success of this starfish.