Its depth range is from the intertidal zone down to about 190 m (600 ft), its typical habitat being on rocks, boulders and pebbles and in forests of giant kelp.

[3] It is the dominant predator in the tidal and shallow subtidal zones of the Falkland Islands.

A study of the community in the Beagle Channel associated with the giant kelp Macrocystis pyrifera showed A. antarctica as being at the top trophic level, feeding on the herbivores grazing on the seaweed, on the filter feeders, on the other predators in the community and on the detritivores.

[4] Breeding takes place between March and July, with the developing embryos being brooded by the parent.

[4][5][3] The juveniles are released between September and November, larger ones departing first while smaller ones remain.