Im sure theres a simple answer to this but Ive been wondering it for years. Archived post. New comments cannot be posted and votes cannot be cast.
SO WHERE DO PNEUMATIC BONES COME INTO ALL THIS?
A birds pneumatic bones are attached to the air sacs. Anterior bones are linked to anterior air sacs in birds, and posterior bones are linked to posterior air sacs, as the diagram below illustrates.
Although the purpose of this connection is still being investigated, it is believed that because the air sacs are affixed to the bones, the breath of the bird gives the skeleton strength and air pressure, helps the bird stay cool by dispersing heated air, and keeps it light enough for flight. When you consider it, a bird’s lungs, air sacs, and bones are used for continuous breathing. How amazing is that!?.
Pneumatic Bones in Birds and You
This week’s post was inspired by my love of learning new things that broaden my understanding of both the avian and human worlds as a birder and naturalist. The majority of us already know that birds’ bones are hollow. In elementary school, we were taught that it makes birds lighter so they can soar. They can breathe with those hollow bones, though, so there’s more to the story that I think is pretty neat.
Let’s begin with the scientific term for these bones: pneumatic (knew-mat-ick) bones. You’ve undoubtedly heard of truck pneumatic brakes, which work by using compressed air in a closed system to apply pressure. The word “pneumatic” has its roots in Greek, where it was originally used as pneuma, which means “wind,” and pnein, which means “breathe,” in the 17th century. ” (Isnt etymology great?) Essentially pneumatic bones are “breathing bones. “Air spaces exist in pneumatic bones, which structurally resemble corrugated cardboard more than solid bone.” This system is “open” in birds so that air can pass through, as opposed to “closed” in car brakes. “.
This is where things start to get interesting: you too have hollow or pneumatic bones; it’s not just birds. Human facial bones are pneumatic, just like bird skulls. Pneumatic bones are essentially your sinuses and are located under your eyes, around your nose, around your lower cheeks, and around your inner eyebrow. You most likely weren’t even aware that you’ve been carrying them around your entire life.
Your face’s pneumatic bones support your nasal sinuses, are lightweight, may offer some impact protection, and because of their hollow chambers, they enhance the resonance of your voice.
Your actual sinuses are hollow cavities lined with epithelial (skin) cells located in the pneumatic bones. Why we have sinuses and their function is being debated. The spaces are supposed to help condition the air before it enters your lungs. This refers to warming or cooling the air before it enters your lungs (imagine ice cream brain freeze, only not so pretty). this is what sinuses prevent). Many of us experience seasonal misery because our sinus tissues swell when we get a cold or have allergies.
BIRD BREATHING BONES
Did you know that dinosaurs had pneumatic bones too? It makes sense if you think about it. Birds are the ancestors of dinosaurs. Sauropodomorphs were the first dinosaurs to demonstrate pneumatic bones in their backbones, specifically Thecodontosaurus caducus and theropod Coelophysis bauri. Sauropods are some of the longest neck dinosaurs that were around, and to have hollow bones in their necks made a lot of sense, it avoided the “pain in the neck” of heavy bones, and allowed oxygen to flow more freely into their bodies. Its estimated that pneumatic bones made their necks so ultra light that their bones were 60-89% air volume (specifically Sauroposeidons).
Birds have pneumatic bones throughout their bodies and in their skulls, whereas most other animals only have them in their faces. These comprise their clavicle, humerus, pelvic girdle, lumbar and sacral vertebrae, and keel, the large chest bone we enjoy for white meat. I want you to sit down and consider this for a moment before continuing. For an idea of how a bird could breathe through its bones, picture someone playing a didgeridoo.
Birds are what I call the original digeridoo players. They have circular breathing. You must learn circular breathing, or breathing in and out, in order to play the digeridoo. While it is a difficult task for humans, it is essential for birds. Birds’ respiratory systems are very different from ours in that they are designed to maximize oxygen extraction from the air for the purpose of fueling their large flight muscles during flight.
Birds have huge lungs compared to their body mass, about 50% larger than ours are by comparison. The thing is, they dont have a diaphragm like we do so their lungs dont expand and contract like ours either. All this gets even stranger. Bird lungs are tucked up under their backbone, and unlike ours that have little sacks much like cul-de-sacs or dead end chambers in the lungs, birds have spongy lungs that allow air to flow through (like water through a sponge).
Eight, nine, or even eleven air sacs, which are essentially hollow balloon-like sacs that hold air and function as bellows, are attached to a bird’s lungs. Usually, there are four or five around the bird’s front and underside, and four at its back. Air can only flow in one direction thanks to these incredibly efficient air sacs. Consider how we breathe: it’s multidirectional, with air entering and exiting in the same directions. Old air mixes with new air and its pretty inefficient. The air in birds moves in a single direction, so when they breathe in, they always get a “fresh breath of air”—old air doesn’t go past it and mix.
I’ve had the good fortune to hold a variety of birds, including ospreys and warblers. One thing I consistently observed was that the birds’ entire bodies moved while they were in my hands and breathing. I initially assumed that they must be terrified and severely “heaving” for air. But I discovered that the circular breathing of birds involves the entire body. Birds must contract their chest muscles to breathe in and out and to pump the “bellows” of their air sacs because they lack a diaphragm like humans do. Because birds must move their chests to breathe, you can literally choke them to death by holding them too tightly!
There are four key steps to a birds circular breathing, and its pretty complex (you can read all about it here). Im not going to explain it all here (thats for another post), the best thing to do is watch this great video:
I’m sure the answer is straightforward, but I’ve been wondering about this for a long time. Archived post. New comments cannot be posted and votes cannot be cast.
FAQ
Do birds have pneumatic bones to help them fly?
How pneumatic bones of birds increase the respiratory rate?
Why do birds have more spongy bone than humans?
Do modern birds have pneumatic bones?