Emperor penguins are strikingly colored, with deep black feathers dorsally, including the head, chin, throat, back, dorsal part of the wings (flippers), and tail. This dark coloration fades to a brownish color as it becomes worn, between December and February. The belly is satin white from the upper breast to venter and including the underparts of the wings. Auricular patches are bright yellow at the head, fading to a less vivid yellow as the patch meets the white breast feathers. The upper mandible is black and the lower mandible is pink, orange, or lilac colored. Males and females are similar in size and coloration throughout the year. Immature emperor penguins are similar in size and coloration to adults, except that their auricular patches, chin, and throat are white. Chicks are covered with silvery-grey downy feathers with a black head and distinctive white eye and cheek patches. Adults weigh from 22 to 37 kg, depending on where they are in the reproductive cycle, as both males and females lose substantial portions of their mass while incubating eggs and tending to hatchlings. They stand up to about 115 cm.

Range mass: 22000 to 37000 g.

Average length: 115 cm.

Other Physical Features: endothermic ; homoiothermic; bilateral symmetry

Sexual Dimorphism: sexes alike