How do the penguins breathe? Do they possess gills or lungs? Do they have special respiratory organs? Can they swim without breathing?
The anatomy and function of the respiratory system play important roles in the dive performance of penguins. Now we will find out whether penguins breathe underwater or not?
- Why do penguins need to dive into the water?
Penguins need to dive inside the water because they feed on sea creatures. They have to dive in order to get their food in the ocean. Most penguins don’t have to dive very deep because they can easily find their prey in the upper water levels. Average underwater dive only lasts for 6 to 8 minutes. In this short time, they find their food and swallow. Emperor penguins are the penguins of very huge sizes and they feed on fish, squid, and krill. They have big stomachs and can’t gratify their hunger by eating small creatures, so they have to dive deep. Their prey resides deep underwater. This species of penguins can hold its breath for up to 20 minutes. Emperor penguins are also known to dive up to 1,800 feet to find their prey. Another species, the Gentoo, is known to dive up to 500 feet.
- How penguins remain alive inside water.
Penguins are birds and they need oxygen for respiration. They have acquired specific adaptations in their blood and muscles for increasing the quantity of oxygen during underwater dive. These creatures utilize each and every molecule of oxygen during the diving process. Ultra-sensitive hemoglobin is present in their red blood cells which monitors the effective use of oxygen. The blood supply is reduced in limbs and blood is sent mainly to vital organs like the heart, lungs, brain, etc. The activity and functionality of hemoglobin are very efficient in penguins and when other organisms undergo severe tissue damage, penguins continue to survive in the scarce availability of oxygen.
- How do penguins save oxygen consumption?
The penguins undergo anaerobic respiration as well. Additional oxygen is stored in the muscle tissues of the penguins by using large amounts of a blood protein called myoglobin.
Anaerobic respiration is also observed in penguins. A special enzyme is present in the penguin’s muscles which allows the muscles to work in the absence of oxygen by neutralizing the lactic acid formation. After reaching the surface and returning to normal breathing, they expel this build-up of lactic acid.
Oxygen consumption is saved further when the penguins lower their heartbeat rate up to 5 beats per minute. So in this way, by avoiding the excessive use of energy, these birds prolong their diving time underwater.
Underwater compression also affects the penguins’ lungs and air sacs. These crucial airways can only provide 1/3 of the necessary oxygen needed for each dive.
- How penguins breathe near the water surface.
It is more convenient for the penguins to dive and swim deeply as they are water-birds by nature and spend most of their lives inside water. Some species of penguins use a swimming technique called porpoising. During this process, they can breathe when they come out of water for a while. The birds come up for air, inhale and exhale rapidly and then again dive into the water. Very high speed is attained by penguins during porpoising. They can attain a speed of 6 miles per hour while porpoising. Being such huge creatures, can king and emperor penguins porpoise?? No. The use of this technique is not observed in the king and emperor penguins. That’s why nature has provided them with the ability to dive very deeply inside water. Other species of penguins can easily find their prey on the surface of the water. The structure and anatomy of the penguins allows them to feel more comfortable and relax in the deep water. They love to dive down fastly. While swimming near the water surface, just before a dive, penguins inhale and collect oxygen inside the lungs and dive into the water.
- How is the respiratory system developed in penguins? How does it help in breathing underwater?
Researchers have studied the respiratory systems of king, emperor and Adelie penguins. The scientific studies show that the estimated oxygen store of the lungs and air sacs of various penguin species constitutes 30–45% of the total body oxygen store in comparison to 5–20% in most marine mammals. It is important to tell here that air sacs of birds are compliant and they can collapse under ambient pressure at depth, but this doesn’t happen in case of penguins. It is unknown how tissue disruption in the walls of the air capillaries and parabronchi is avoided at depth. Their lungs do not squeeze at depth. All other birds can undergo pulmonary barotrauma (squeezing of lungs at depth due to high pressure). Why doesn’t this happen to penguins? The mechanisms are still unknown. Perhaps, smaller mass-specific lung volumes in deeper diving species allow for lower air capillary and peribronchial volumes, and, thus, greater protection against barotrauma in the deeper divers. However, these differences in lung volume are probably most related to differences in body mass, metabolic rate and gas exchange requirements. It is also unknown whether greater protection against lung barotrauma is afforded by a further reduction in para-bronchial and/or air capillary volumes in the deeper diving species. The scientists have hypothesized that the penguin lung is relatively rigid as in other birds during spontaneous ventilation, but the lung expansion at positive inflation pressures suggests that some compression of the lung may occur at depth.
This is especially so in the deeper diving king and emperor penguins, in which lung volume increased by 25% at the highest inflation pressure, and lung compliance was approximately six times greater than in the shallower diving Adélie penguin.
This expansion of the penguin lung during inflation presumably occurred primarily in the parabronchi and air capillaries because, as measured in the Humboldt penguin, the primary bronchi constitute less than 4% of the total lung volume, while the parabronchi/air capillaries constitute about 95% of the air volume in the lung. For these reasons and the assumed greater rigidity and resistance to compression of air capillaries, it is suggested that compression and a reduction in the volume of the parabronchi may afford further protection against pulmonary barotrauma in deep-diving penguins. So although a larger body size and relatively smaller lung volume confer an advantage for deeper diving penguins in the avoidance of barotrauma, these differences among the species are probably most attributable to body mass and metabolic rate.
- How air sac volume varies when penguins stay underwater?
It is important to.mention here that the maximum pre-dive respiratory air volume is still unknown in penguins. But air sac volume continued to increase with greater inflation pressure. Although the maximum air sac volume prior to a dive remains unknown, higher values would afford greater baroprotection and a larger O2 store. A larger ratio of air sac-to-lung volume has been proposed as a possible protective mechanism in diving birds. The scientists kept 30 cm H2O (2.94 kPa) inflation pressure to represent a maximum air sac volume. These air sac values were approximately 2.2, 2.9 and 3 times the allometrically predicted values for these Adélie, king and emperor penguins, respectively. So we can easily understand that air sac volume increases proportionally with an increase in inflation pressure.
- Penguins don’t have gills.
Unlike fish, penguins don’t have gills. As we have discussed earlier, they have lungs for respiration. They have to breach during swimming but fish don’t need to do so. Fish have a special mechanism of taking water in and extracting oxygen out of it. This function is performed by gills. So fish are not dependent on air for breathing. Penguins lack the gills. They breathe in air through a mouth and nostrils. The air gets through the air tube to the lungs where the gaseous exchange takes place. In the lung, oxygen is given from the inhaled air to the blood. The red blood cells transport this oxygen to the heart firstly and then it is pumped through the whole body. The oxygen is given to cells in organs so that they can use it for energy production. Carbon dioxide is produced by these reactions and is transported back to the heart by the blood. From there the blood with high carbon dioxide content flows back to the lungs where the carbon dioxide can get outside the body with exhaled air. So this was the whole mechanism by which penguins breathe.
A very detailed scientific study shows that penguins cannot breathe aerobically underwater and have adapted themselves to use oxygen effectively inside water. They are birds and possess lungs as respiratory organs. Gills are absent in them, so they do depend on air for gaseous exchange. They reduce the use of oxygen and also undergo anaerobic respiration underwater. The presence of special mechanisms in their bodies helps them to minimize the use of oxygen and they can hold their breaths for a very long time. As a result, they get their seafood and keep themselves alive.