Penguins

When a penguin dives into the Antarctic Ocean, it is greeted by a water temperature 40 degrees below its own body temperature. (A person without a wet suit can live about 10 minutes in water that cold.) Thus, penguins have adapted certain mechanisms to keep themselves warm. First, each penguin has a 0.7-1.1 in (2-3 cm) thick layer of fat and thick, waterproof plumage to insulate itself. Further, when in the water, the penguin is much more active than when on land. Thus, its metabolism increases, producing more metabolic heat.

The coldest-weather species (the Emperor penguin) has made additional adaptations for surviving the most extreme cold. The Emperor has the largest body of any penguin, measuring about 3 ft (1 m) tall and weighing 88 lb (40 kg). Thus, compared to birds with a smaller body, it has relatively less surface area exposed to the cold compared with its weight. It also has the most fat of any penguin species and can live for two to four months during the winter without eating. The Emperor also has more extensive feather cover than other species, including feathers on its bill and feet, except the toes. Its flippers are shorter and feet are smaller than its relatives, reducing their exposure to the cold.

This heat insulation is very effective, sometimes too effective. The problem with the insulation is that penguins are always in danger of overheating. This is especially true when they are fighting or running during the warmest months of the polar year—December, January, and February.