- Spiracles and respiration
- Whale lungs
- Methods to conserve oxygen
- Less effort, more oxygen
- Bradycardia
- High tolerance to carbon dioxide (CO2)
- Breathe with awareness
- Respiratory process
- References
The whales breathe through the lungs, reason usually rise to the surface of the ocean to air. It is important to note that, because whales live in the oceans, many people consider them to be fish.
However, whales are actually mammals. Mammals are a group of animals that breathe using their lungs, that give birth to their young (unlike other animals that lay eggs) and feed them with mother's milk.
Different parts of the exterior of a whale (illustration of a blue whale). Source: Jim Thomas CC BY-SA 3.0 (https://creativecommons.org/licenses/by-sa/3.0)
There are approximately 80 species of whales, which are divided into two suborders, taking into account the anatomy of the species: baleen and toothed whales.
Barbels are the largest of the two suborders and have no teeth, but barbs (hence the name), which are thick bristles. These whales are born with two spiracles, holes that they use to breathe.
For their part, the serrations are smaller and have teeth. These whales have only blowholes to breathe. Some scientists believe that the toothed whales transformed one of their blowholes into an echolocation system.
Spiracles and respiration
The word "blowhole" comes from the Latin spiraculum, which means "vent." Spiracles are special holes that some animals have to breathe. The spiracles of the whales are located on the top of their heads to facilitate breathing and connect directly with their lungs.
These spiracles act as a pathway to the windpipe, allowing air to pass into the lungs.
The location of their blowholes means that whales can breathe practically without having to strain, because they can rest on the surface of the ocean and capture the oxygen necessary to live.
When whales swim underwater, the muscles around the blowhole contract to prevent the water from reaching the lungs.
It should be noted that whales cannot breathe through their mouths, since the trachea of these animals is not connected to their esophagus. This division is important, since having separate tubes for eating and breathing prevents the respiratory system from being blocked by food debris.
In addition, this division allows the whales to be able to eat underwater, without having to worry about their lungs filling with water.
The blowhole is a hole in the top of the whale's head that allows it to breathe / Photo retrieved from dkfindout.com
Whale lungs
In order to survive underwater, whales have developed special lungs that allow them to inhale extra oxygen and transfer it to blood vessels, where it can be used by the body.
According to some researchers, whales are capable of using up to 90% of the oxygen they inhale, compared to humans who only use about 15% of the oxygen we inhale.
As for the length of time that whales can hold their breath, it varies according to species and size.
Some can hold air in the lungs for a few minutes, 5 or 7, so they must constantly rise to the surface. Other species can hold their breath for 100 minutes, or even longer.
Methods to conserve oxygen
Less effort, more oxygen
Whales use as little effort as possible when swimming. When they submerge, the blood is transported only to the parts of the body that need oxygen: the heart, the brain and the muscles that they use for nothing; in this way, they conserve oxygen for longer.
Bradycardia
Whales slow their heart rate, a process known as bradycardia, to reduce the amount of oxygen consumed.
High tolerance to carbon dioxide (CO2)
Whales have a high tolerance to carbon dioxide (CO2), much higher than that of any other mammal; this allows them to immerse themselves in the ocean for longer.
Breathe with awareness
Whales are considered conscious breathers, since they work as little as possible when swimming and hunting in order to conserve oxygen.
Also, these animals never fall asleep completely, since losing consciousness for a long period of time could mean death by suffocation.
During the rest, half of the brain of the whales sleeps, while the other half remains alert to be able to act quickly in case they need oxygen or have to flee from predators.
In this sense, whales rarely reach the deep sleep state characterized by rapid eye movement (REM).
Respiratory process
1 - The muscles around the whale's blowhole contract and open as they rise to the surface of the ocean, exhaling carbon dioxide. When whales have been submerged for a long time, it is common to see them expel water through their blowholes, a sign that they are exhaling.
2 - Fresh air is inhaled and, later, the muscles relax, closing the blowhole and preventing the passage of water.
3 - The air travels through the pharynx, larynx, trachea and finally reaches the lungs.
4 - Oxygen is transported to the blood through blood vessels located in the lungs.
5 - The heart pumps oxygenated blood to the parts of the body that require oxygen.
References
1. Zagzebski, Kathy (2009). How do whales breathe? Retrieved on April 19, 2017, from nmlc.org.
2. How do whales breathe? Retrieved on April 19, 2017, from whalefacts.org.
3. Can whales breathe underwater. Retrieved on April 19, 2017, from whalefacts.org.
4. How do whales and dolphins sleep without drowning? Retrieved on April 19, 2017, from scientificamerican.com.
5. How do whales breathe? Retrieved on April 19, 2017, from dkfindout.com.
6. Animal Respiration: Whale. Retrieved on April 19, 2017, from animalrespiration.weebly.com.
7. Scientist capture images of sleeping whales. Retrieved on April 19, 2017, from telegraph.co.uk.