Biology
Aquatic Locomotion and Drag Reduction in Penguin Swimming
Quick fact
Emperor penguins swim over 10 times faster than a human Olympic swimmer, reaching speeds close to 30 km/h while expending only about half the energy of a fish of similar size.
Why this is interesting
Penguins are the fastest swimming birds, but they never took to the air. How do these seemingly awkward waddlers become so streamlined and agile in water?
Read the full explanation
Understanding Aquatic Locomotion and Drag Reduction in Penguin Swimming
Imagine a submarine designed to be as sleek as possible—that's a penguin in water. Their bodies are a masterclass in drag reduction. The most striking feature is their fusiform body shape: like a teardrop or a well-designed aircraft fuselage, broader at the front and tapering at the back. This shape minimizes the drag caused by water pushing back against a blunt surface. For comparison, a human swimmer has a rather inefficient shape—wide shoulders and hips create turbulent wakes. Penguins also have short, stiff feathers that trap a layer of air, which not only insulates them but also makes their surface smoother and more water-repellent, further reducing friction.
A deeper explanation
But the real secret to their underwater agility lies in their wings. Penguin wings are not like those of flying birds; they are modified into rigid, flipper-like structures that act as highly effective hydrofoils. When a penguin swims, it moves its flippers up and down, slightly twisted at the angle of attack. This motion generates lift and thrust, similar to how a dolphin's tail works, rather than pushing against the water like a paddle. This wing-propelled diving is remarkably efficient. Furthermore, penguins have dense bones, which reduce their buoyancy, allowing them to dive deeper and swim with less energy spent on maintaining depth. To further boost efficiency, some penguins employ a technique called 'burst-and-glide'—they burst into fast propulsion and then glide for short periods, conserving energy, much like how a long-distance runner paces themselves. The combination of a streamlined body, efficient flippers, and a controlled buoyancy makes penguins one of the most energy-efficient swimmers in the ocean.