As a zoo and wildlife veterinarian, I occasionally look after penguins in the wild as well as in aquariums and zoos. When I have to take X-rays of an injured bird that may have a broken bone, is unwell, or is having difficulties moving, I’m always fascinated. Penguins may appear to be basic, torpedo-shaped ice wadlers, but their bodies are actually highly sophisticated.
They have skeletons and joints that are comparable to people and animals you could see on a daily basis, such as dogs and cats. They have knees and elbows as well, but just half as many bones. There are 206 bones in the human skeleton. A penguin has only 112 cells in its entire body. With feathers, wings, and a physique that permits them to soar far in the sky, all birds developed for flight. Penguins’ skeletons have developed over time to have less bones in order to achieve liftoff.
How did they manage it? Some of their bones, particularly their ankles, literally bonded together. A bird’s leg bone connects directly to its foot and toes, unlike humans, who have two primary ankle bones. Birds’ spines also contain fewer bones than those of many other animals. Their lower back bones fused together to form the synsacrum, a single bone. The dinosaurs were the only other animals with this sort of backbone.
This allows birds to keep their bodies in a horizontal position while flying or swimming without tiring out their back muscles. Bird bones, in general, are one-of-a-kind. They’re light and hollow, allowing the animal to take to the air. Birds’ bones are filled with air gaps, and they have nine air sacs that surround their lungs because they require a lot of oxygen for an intense activity like flight.
“But wait,” you might say, “penguins don’t fly at all.” They evolved for a life on land and in the water, and their skeleton differs from that of many other birds. The original penguins, which developed some 66 million years ago after the dinosaurs died out, were flightless. They had evolved into superb swimmers ten million years later. Most modern organisms spend up to 75% of their time in the ocean. That meant they needed to gain weight in order to dive underwater and forage for food.
Penguins have dense, heavy bones that lack the air spaces found in flying birds. This compensated for the lack of air sacs around their lungs. Like a scuba diver who belts on a weight belt to plunge, their thick bones keep them from floating up to the water’s surface. Penguins’ wings are also unique since these birds must swim rather than fly. Penguin wings have evolved into what appear to be small, flat, inflexible fins that do not bend like those of flying birds. In comparison to other birds, they also have less bones.
Their wings operate as paddles, allowing them to rush through the water. Gentoo penguins can swim at speeds of up to 22 miles per hour. That’s a lot quicker than Olympic champion swimmer Michael Phelps, who set a world record for humans by swimming at 5.5 miles per hour. Penguins can hunt for fish, krill, and other food by descending swiftly and diving exceptionally deep thanks to their massive bones and powerful finlike wings.
An emperor penguin can dive to a depth of at least 1,500 feet, or nearly five football fields. Penguins are champions of open water thanks to their fewer thick bones and other remarkable adaptations. The Discussion, Julie Sheldon, University of Tennessee Clinical Assistant Professor of Small Animal Clinical Sciences, The Conversation has given permission to reprint this article under a Creative Commons license. Read the full article here.
