The emperor penguin is the heaviest and tallest of all penguins reaching up to 90 pounds in weight and 4 feet in height. Adaptations to the severe Antarctic climate are just one possible explanation for their massive size. Thanks to the layer of blubber beneath their skin their ability to retain body heat is critical to their survival in the freezing environment. They may be able to preserve energy by not eating for long stretches of time when incubating eggs or caring for chicks because of their small stature.