The Cetacean Respiratory System.
Although cetaceans live their lives surrounded by water, the way their bodies intake oxygen is so biologically similar to ours.
The biggest difference is breathing in and out. The instinct of us humans is to breathe in first when we reach the surface of the water, but cetaceans breathe out first, and then they breathe in. They do this to blow off any water remaining at the surface of their blowhole, preventing water from reaching their lungs. This is also what makes the famous whale water spout!
Another clever difference is we are unconscious breathers, meaning we don't need to tell our bodies to breathe because it does it automatically, but that's a different story for marine cetaceans. Their blowhole flap is located on the top of their body, behind the melon. The flap is a voluntary-moving muscle they can control themselves and they even manoeuvre the flap for their range of vocalisations.
Although cetaceans do have a diaphragm, a huge and muscular par that moves the lungs to suction air in or push air out, it lies more horizontally than in other land mammals.
Once the air is breathed in after they breathe out, the air travels down a thick c-shaped tube known as the trachea, the c-shaped cartilage helps keep the tube open, preventing breathing difficulties and suffocation. The trachea transports the air to the bronchi, tubes that separate into each lunch, where the air travels through the tiny tree branch-shaped bronchioles which transport the air to millions of alveoli, tiny sacs where gas exchange happens.
The lungs are coated with a layer of red blood cells which absorb the oxygen from the air and through the journey, lymphocyte cells will filter out any unwanted materials and organisms. Capillary blood vessels are one-cell thick to make sure as much oxygen can make it to the vessels as possible while the lymphocytes do most of the fighting work. While the oxygen makes its way into the body, carbon dioxide is exiled its way through to the lungs where it'll be breathed out. The taken oxygen will make its way to the heart once it's in the capillary vessels.
The blowhole muscular flap is closed shut, making an air-tight border.
Image by me, do not use without written permission.
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