Whales breathe through lungs, just like their closest relatives, land mammals. However, the fact of being in the aquatic environment forces them to come to the surface to breathe. They are adapted to prolonged diving, which is why they can hold their breath for long periods of time, and surface only when oxygen is needed to recover. There are a few factors that influence how often they have to surface to breathe, and one of them is swimming speed. At higher speeds, they will be expending more energy, so they will need to surface more often. Among marine mammals, whales are the best at holding their breath, since the observed record is held by the Cuvier's Whale (Ziphius cavirostris), which is capable of diving up to 137.5 minutes at a depth of 2992m.
If you want to continue learning about how whales breathe, continue reading this article on our siteand you will know everything about his breathing.
Where do whales breathe?
Whales breathe through spiracles, but what exactly are they? The cetaceans, the family to which the whales belong, have undergone anatomical adaptations to facilitate this breathing. The most important consists of a displacement of the nostrils or nostrils towards the dorsal part, just above the head. At this time, the holes are called spiracles. This superior position of the spiracle allows them to rest on the surface without having to make a great effort, in addition to allowing them to breathe very quickly, which we will comment on later.
Whales cannot breathe through their mouths, as they have isolated tubes for breathing and feeding, which is why they can feed safely for water to enter the lungs. Likewise, not all species of whales have the same number of spiracles. For example, baleen whales or baleen whales have two holes, while the rest of the whales or odontocetes have only one hole.
How do whales breathe?
Whales, unlike other mammals, have almost voluntary breathingThe short time they spend on the surface forces them to exchange CO2 for O2 very quickly, and that is why in marine mammals gas exchange is bidirectional. Gas exchange occurs in the alveoli, the sac-like endings of the lungs.
Whales can expel air both under water and on the surface In the first case, the air reaches the surface in bubble shape. As a curious fact, we can say that some whales use these bubbles to catch fish in "bubble nets", allowing others of their species to take advantage of it. In the second case, on the other hand, the air is expelled already on the surface. However, the introduction of new oxygen can only be practiced outside the water.
Type of breathing of whales
Whales are considered to have a type of pulmonary respiration. Next, we'll take a look at exactly how whales breathe.
Whales' breathing process
The breathing process of whales begins with the expulsion of CO2. Inside the water, we have already seen that they do it in the form of bubbles. Outside, on the other hand, they expel a large amount of air and water through the spiracle, a phenomenon that we can define as "blowing". Now, what exactly are these puffs?
The puffs so characteristic of whales are produced by the rapid emptying of their lungs So, when we watch a whale expel a large amount of water and with a lot of force through the spiracle, we know that what it is doing is emptying the lungs. This emptying is so accelerated thanks to the fact that they have a much more flexible chest wall, as well as very powerful chest muscles, which also allows them to compress the lungs until they are practically empty. In this way, they can store as much oxygen as possible to take advantage of it during the dive. As a curiosity, blue whales are capable of emptying their 1500 l lungs and refilling them in just 2 seconds. After this huffing expiration, there is a much slower inspiration, followed by complete closure of the airway and apnea.
Contrary to what might be expected, whale lungs are no larger (in relative size) than those of land mammals. However, they have a much higher tidal volume, that is, they are capable of much deeper inspirations and expirations. Whales' breathing patterns vary greatly between species due to their behavior and activity.
On their long dives, the alveoli that form the whales' lungs are in danger of collapsing due to high pressure, which is why at 50-100 meters deep all the air present in them is compressed by their powerful muscles, passing all the alveolar air to the bronchioles and trachea of the lungs, much more resistant than the alveoli. In this way, part of the oxygen is also absorbed by compressing the air in the alveoli, giving them an extra supply when they are deep.
Other adaptations associated with whale breathing
In addition to the adaptations already mentioned in the respiratory system, cetaceans, and in this case whales, have also undergone adaptations in the circulatory system in order to improve this gas exchange. They are as follows:
- An anatomical adaptation of cetaceans is the “ rete mirabile ”, which consists of a net of blood vessels present in the thoracic cavity and extremities of the animal. These vessels serve as a reservoir of oxygenated blood to supply during diving.
- Another adaptation is aimed at the molecule that stores oxygen in the muscles, the myoglobin Unlike hemoglobin (a protein that transports blood in the rest of the body), myoglobin is found exclusively in the muscles. In the case of whales, they have a 10 to 30 times higherconcentration of this molecule in their major swimming muscles than in the muscle of any land mammal. In addition, the blood vessels of the most diving species are larger than those that dive less, all this in order to store a greater amount of oxygen in the blood. They can also reduce the blood flow in some organs, such as the kidney or the digestive system, thus prioritizing the oxygenation of vital organs and swimming muscles.
How do whales breathe when they sleep?
Whales, unlike a land mammal, need to come to the surface to breathe while they are asleep. To solve this problem, whales have a very light sleep, characteristic of cetaceans, which is called “ unihemispheric sleep”. What exactly does it consist of? In putting one of the cerebral hemispheres to sleep to allow the other to continue working, guaranteeing that the whale does not sink and can continue breathing.
Thanks to this adaptation, it could be said that they stay half awake, which allows them to come out from time to time to take a quick breath and continue sleeping. This type of breathing of whales during sleep is not exclusive to them, dolphins, for example, also practice it. Find out how dolphins sleep in this other article.
If you want to know more curiosities about whales, don't miss how they reproduce with this other article: "How do whales reproduce?"
