Some taxonomic authorities, including the International Ornithologists' Union, split the group into the species listed below.

[3] The imperial shag has a total length of 70–79 cm (28–31 in) and weighs 1.8–3.5 kg (4.0–7.7 lb), with males usually larger than females.

It possesses a distinctive ring of blue skin around its eyes, an orange-yellow nasal knob, pinkish legs and feet, and an erectile black crest.

The colonies are usually relatively small, but some consist of hundreds of pairs and are often shared with other seabirds such as rock shags, southern rockhopper penguins and black-browed albatrosses.

[11] The diet of this species consists of small benthic fish, crustaceans, polychaetes, gastropods and octopuses.