Why Penguin's feet do not freeze?
One of most important and interesting aspects of penguins is how they keep themselves warm and dry in the extreme cold conditions. A man standing barefoot on ice would quickly get frostbitten, penguins can do so all their lives with no damage at all.
These highly specialized marine birds are adapted to living at sea - some species spend as much as 75% of their lives at sea. Penguins are usually found near nutrient-rich, cold-water currents that provide an abundant supply of food. The penguin's body is adapted for swimming. A penguin has a large head, short neck, paddle-like flippers and elongated body. The tail is short and wedge-shaped. The legs and webbed feet are set far back on the body.
All adult penguins have dark backs and white or yellowish-white fronts. Their dark backs are usually black. However, their beaks, necks, and feet may be brightly colored. Some penguins also have colorful crests of feathers on their heads.
The colors of the penguins help them blend in with their surroundings. A school of fish swimming above a penguin may not even notice the bird. That's because the penguin's dark back blends in with the dark waters below it. An enemy or prey may not see a penguin swimming above it either. That's because the penguin's pale belly blends with the bright light of the sky or ice above it.
How Do The Penguins Keep Themselves Warm And Dry In The Extreme Cold Conditions?
The Penguin feathers are waterproof. They keep penguins dry underneath, even while the birds are swimming. If penguins don't keep their feathers in very good shape, they don't stay waterproof. So penguins spend several hours a day preening, or caring for their feathers. Penguins use their beaks, flippers, and feet to preen. For extra protection in the water, penguins spread oil on their feathers. The oil comes from a special gland near their tail feathers.
Penguins shed their feathers because they become worn and damaged. When penguins shed their old feathers and grow new ones, it is called molting. Penguins molt once a year. Penguins always molt on land or on ice. Until they grow new waterproof coats, they can't go back into the water. And the water is where they need to go to find food. Sometimes penguins might have to go for more than a month without food while they molt. To prepare, penguins eat as much as they can during the weeks leading up to the molt. Eating so much helps them add fat to their bodies. The penguins live off the fat while they grow new feathers.
Penguins are warm blooded animals
Penguins are warm blooded animals and they maintain internal body temperatures similar to warm blooded animals in any other climate zone - that is about 35-42Â°C (95-107Â°F). Tropical animals with more variable body temperatures such as reptiles and amphibians can warm up by basking in the sun if they cool down and they never cool down that much. A large (bigger than a small insect) Antarctic animal will never get enough energy from the surroundings to become active if it allows itself to cool, so they have to stay warm to be active.
Warm blooded animals in cold climates are pretty large, even the smallest Antarctic birds are on the large side and the smallest Antarctic penguin, the Rockhopper is 2.5kg. The Adelie and Emperor penguins of the deep south are larger still. Adult weights are 5kg for the Adelie and 30kg for the Emperor - a similar size to an overweight 10 year old child, but with a man-sized chest measurement.
The larger the animal, the smaller the surface-area :
volume ratio and hence a less relative area of its body is exposed and this helps the penguins to stay warm. The dark colored feathers of a penguin's dorsal (back) surface absorb heat from the sun through radiation and help the penguins to warm up.
Penguins are endotherms, which means that they have the ability to keep their body temperature at constant levels even when the surrounding temperature is very different. To regulate the body temperature they need to prevent the heat loss to the surroundings and insulate themselves well.
The heat loss in penguins can take place in two different ways: convection and conduction.
Convection is the transfer of heat via fluid molecules. Heat exchange by convection depends primarily on the temperature difference between the skin and the air and on air movement. It can be controlled by adequate clothing, the feathers in the case of penguins.
The contribution that conduction makes to the heat loss depends on the thermal conductivity of the materials in immediate contact with the skin. This heat loss occurs when the body parts of penguins come in contact with the ice or snow which is at very low temperature.