Penguins can swim amazingly fast underwater, a stark contrast to their terrestrial waddling. Streamlined bodies and webbed feet help, but what really gives them their speed and agility is their flippers.
Appendages used for flying in most birds have been transformed into flippers for penguins. These hard, bony structures have a rounded leading edge and a tapered trailing edge that push hard against the water to propel the penguin at speeds up to 35 km/h or 22 mph! Typical cruising speeds are, however, around 10 km/h or 7 mph. Gentoos are said to be the fastest of all the penguins.
As you can see in the photos, the flippers have a very streamlined shape. They beat their flippers in the water as a flying bird beats its wings to fly. The big difference is that the penguin flippers must be able to return to starting position without drag in the dense water. The rounded shape works perfectly for this maneuver and allows quick and consistent forward movement.
Upon initial inspection, the photos also show the flipper as looking very straight and rigid. There is, however, joints within this stiff structure that give the flipper a subtle “S” shape as shown in the photo of the king penguin below (top) as well as the gentoo lying down (bottom).
These joints functions very much like an elbow and wrist, allowing the flipper to bend in ways that likely helps the penguin swim faster. While our group has not studied the hydrodynamic effects of the penguin anatomy, we theorize that these joints are used either to bring the flipper back to its starting position with less drag or simply to help the bird maneuver better under water.
Another interesting use for the flipper is its ability to help the bird thermoregulate. During cold weather, the penguin presses its flipper tight against its body to retain heat. But during hot periods, the animal will hold its flipper straight out from its body into the air, allowing the highly vascularized flipper to release heat as wind blows over and under the flipper.
Lastly, a less-obvious function for the flipper is for self-defense. The flipper is used both in fighting with other penguins as well as a defense mechanism against predators. The flipper is formed with dense bone that is both tough and hard and will produce a significant injury when the penguin flaps briskly with its strong muscles. It has been reported that one penguin researcher had her arm broken when hit by the flipper of a king penguin. We have also witnessed bloody fights when penguins hit each other, a conflict that often arises when a bird steals nesting material from another bird.
We all know that penguins are excellent swimmers, making the transformation from clumsy, waddling birds to agile performers of beauty once they hit the water. It’s easy to think about their flippers and how they use them to maneuver in the ocean. But what about their feet? Many people don’t realize it, but penguins actually spend a lot of time walking.
The gentoos from one colony we studied walked nearly a full kilometer from their nests to the ocean. A kilometer to the water, a kilometer back; sometimes twice a day. Another species, emperor penguins, make an even more arduous journey. They may waddle for tens of kilometers across the ice to reach open water, just so they can eat. I’ve also personally seen adelies twenty kilometers from the nearest source of water. Rockhoppers — the extreme adventurers of the penguin world — jump along jagged, rocky cliffs to reach their nests. All of these swimmers put a lot of distance on land, something that’s easy to overlook.
So what does a penguin wear on its feet? Like all birds, their legs and feet are covered in scales inherited eons ago when they diverged from dinosaurs. But unlike reptiles, the scales on a penguin’s feet do not feel scaly. That exposed skin is actually quite soft which is surprising considering the distance they put on those little appendages. Supple, yet tough, they don’t have callouses that might be expected considering the wear they get, although they do have padded areas that provide some protection. These pads, however, are not as prominent as those of mammals such as cats and dogs. Just thick and tough skin that gets a daily pedicure from the sandy beaches, followed by a mineral treatment in the ocean. Sounds nice, eh?
To add to that resilient skin, long claws emerge from the three dominant toes along with a smaller claw on the vestigial toe. The claws are much like a dog’s claws, thick and dull and good for gouging out dirt. One use for the claws is to aid in gripping the terrain as they walk and hop along the trail. In the colony, they often lay on their bellies and scratch at the soil to build a nest. And, if caught by a predator, they claw with their feet like a cat uses its back legs to tear through anything near its belly.
Lastly is the webbing between the toes. Like all web-footed animals, the webbing helps the penguin swim better in the water. These wide feet also act well as rudders to help the bird maneuver quickly under water.
The photos above show both the tops and bottoms of a gentoo penguin’s feet. Multi-purpose appendages for walking long distances over variable terrain as well as helping them steer underwater. Next blog: a close-up of the flipper!
Sometimes when the wind dies down and the sun dips below the horizon, the penguins have front row seats to some of the most beautiful views on the planet. Just after sunset, the gentoos in this colony settle into their nests for the night, though they never seem to truly relax. I imagine it comes with the territory of living in closely packed quarters, a bird every half meter. But although the honking and braying sounds continue through the night, they sound almost calming in the still dark of the oncoming night.
Check out this video to see dusk in the penguin colony for yourself.
This is a cute and funny little video about a clueless penguin and its poor little chick. Check it out!
Check out the latest video posted on our YouTube channel. Yes, there really is treasure at the end of the rainbow. 🙂