Salamanders are amphibians, which means they live part of their lives in water, and part on land. But have you ever wondered how salamanders breathe in each of these unique environments?
Salamanders breathe either through their gills, lungs, or skin and thin membranes in their mouth and throat. Most salamanders start their lives with gills but develop lungs as their mature into adults. Some adult salamanders do not develop lungs, but instead mature to breathe entirely through their skin.
Aquatic salamanders usually keep their gills as they mature in adults, but some such as the hellbender lose their gills and develop to breathe in the water mostly through their skin.
Salamander Larvae Breathe Through Their Gills
Salamanders start their lives as tiny embryos inside an egg sack. With time, tiny larvae (baby salamanders) hatch from these eggs.
These larvae are fully aquatic and have external feathery gills attached to either side of their head, just where their necks should have been.
At this stage, salamanders breathe in the water through their gills, just like fish.
Their gills have an extensive capillary network; Oxygen that is dissolved in the water that comes in contact with their gills is absorbed into their bloodstream via diffusion.
At the same time, carbon dioxide from the bloodstream passes through the gills and is diffused into the water.
Larvae Turn Into Adults
After a few months, to as long as three years in some species, the larvae will go through a process known as metamorphosis and transform into adults.
During metamorphosis, terrestrial (land-dwelling) salamanders will lose their gills and develop strong legs for walking on land.
Many (such as the tiger salamander) also develop lungs for breathing air. However, some terrestrial salamanders do not develop any lungs, but instead, develop to breathe through their skin and thin membranes in their mouths and throat.
Some Adult Salamanders Breathe Using Their Lungs
Once they have fully transformed into adults, salamanders such as the spotted and the tiger salamander will have well-developed lungs, which they use to breathe air. They take air through their nostrils, and down into their lungs.
That said, it is important to note that how salamanders take air into their lungs is slightly different from humans. Salamanders do not have a rib cage or diaphragm to move air in and out of their lungs as we do.
Instead, they move air in and out of their lungs through a process known as “gular pumping”, also known as “buccal pumping”.
How Gular Pumping Works
This is basically a process of moving air in and out of the lungs’ through the use of the mouth and throat muscles.
To breathe in, the salamander will lower the floor of its mouth, which causes the throat to expand. Air then rushes into the throat, through the mouth, and the open nostrils.
The salamander will then close its nostrils, and raise the floor of its mouth, which causes the throat to contract, and pushes the air into the lungs.
Once the air is in the lungs, oxygen from the air is then absorbed into the salamanders’ bloodstream. At the same time, carbon dioxide from the bloodstream is diffused into the air.
To breathe out, the salamander will lower the floor of its mouth, which causes the throat to expand and draws the air from the lungs, and into the mouth. It will then open its nostrils, and raise the floor of its mouth, to push the air out of the nostrils.
All this happens in split seconds, and without any conscious effort from the salamander, just like how we breathe without thinking about it.
Other Adult Salamanders Breathe Mostly Through Their Skin
Some salamanders, such as the red and the red-backed salamander do not develop lungs after transforming into adults. Instead, they develop to breathe entirely through their skin and thin membranes in their mouth and throat. These are called “lungless salamanders”.
Salamanders have moist semi-permeable skin and very thin absorbent membranes in the mouth and throat. Their skin also has a large network of capillaries and blood vessels close to the surface.
The oxygen that comes in contact with their skin and membranes is absorbed into the bloodstream via diffusion. At the same time, carbon dioxide from the bloodstream passes through the skin and membranes and is diffused into the atmosphere.
This process of “skin breathing” is known as cutaneous respiration is very similar to what happens inside of our lungs.
To efficiently breathe, salamanders have to keep their skin constantly moist by secreting a mucous coating. They can only absorb oxygen through their skin if the skin stays moist. If it dries up, they can suffocate and die.
Adult Aquatic Salamanders Usually Have Gills
Unlike terrestrial salamanders, aquatic salamanders live entirely in the water, even after transforming into adults. This means they have features that are adapted for life in the water, rather than on land.
Aquatic salamanders such as axolotls, sirens, and mudpuppies keep their gills as they develop into adults. They use these gills to breathe in the water, just like the larvae.
However, sirens and axolotls also have fully functional lungs which they develop as they transform into adults. They use these lungs to occasionally breathe air from the water surface.
Mudpuppies, on the other hand, do not have functional lungs. Their lungs are largely non-functional and are mainly used for buoyancy, rather than breathing.
These lungs inflate and deflate like a fish’s swim bladder, enabling to salamander to float or sink into the water.
Some Aquatic Salamanders Mainly Breathe Through Their Skin
Aquatic salamanders such as the hellbender lose their gills as they transform into adults. These salamanders develop to breathe in the water through their very wrinkled skin.
Dissolved oxygen in the water is absorbed through their skin, and into their bloodstream. At the same time, carbon dioxide from the bloodstream passes through their skin and diffuses into the water.
Here is a table to summarize everything easier:
|Aquatic Salamanders That Breathe Using Gills, but Also Have Fully Functional Lungs to Breathe Air||Aquatic Salamanders That Breathe Using Gills and Have Non-functional Lungs Mainly Used for Buoyancy||Aquatic Salamanders That Do Not Have Gills and Mainly Breathe Through Their Skin|
|Axolotls||Chinese giant salamanders|
|Olms||Japanese giant salamanders|
Fun fact: An experiment was performed where one hellbender’s lungs were surgically removed to see what the effect would be. Interestingly, the hellbender survived and continued to live comfortably, just like it did before.
This is strong evidence that hellbenders do not use their lungs to breathe.
How Do Terrestrial Salamanders Breathe Underwater?
Terrestrial salamanders breathe underwater through their skin via cutaneous respiration. Dissolved oxygen in the water is diffused through their skin, and into their bloodstream, and carbon dioxide is diffused out.
However, this method of breathing does not give them all the oxygen they need, so they can only be underwater for a limited time before they have to resurface to get oxygen from the atmosphere.
Exactly how long a terrestrial salamander can stay underwater depends on how much oxygen it can absorb from the water through its skin.
This is usually affected by: the temperature, the nature of the water, and how active the salamander is.
Cold water can hold more dissolved oxygen than warm water. This means the oxygen content of the water will be higher when the temperatures are low.
Also, salamanders will have a higher rate of metabolism at warmer temperatures and a lower rate of metabolism at colder temperatures.
All this combined means salamanders can stay underwater for much longer at colder temperatures than they can at warmer temperatures.
The Nature of the Water
Fast flowing water generally has more oxygen than still water. This is because the movement of the water makes it easier for air to dissolve into the water.
In still water, oxygen only dissolves on the water surface, so the deeper you go into the water the less oxygen there is.
For this reason, salamanders can stay underwater in fast-flowing water for much longer than they can in still water.
How Active the Salamander Is
Salamanders will have a higher oxygen demand when they are working hard (escaping a predator, for example), and a lower oxygen demand when they are at rest.
This means they can stay underwater when at rest, for much longer than you can when they are very active.
Some Adult “Terrestrial” Salamanders Breathe Through Their Gills
Terrestrial salamanders are supposed to lose their gills as they transform into adults. However, this development occasionally takes an odd turn and larvae mature into adults without first going through the normal process of metamorphosis.
This is known as “neoteny” and is most common with tiger salamanders.
It usually happens when the salamander larvae are in a pond with lots of food, making it unnecessary for them to metamorphose and leave the water.
Sometimes, it happens when the conditions on land are overly harsh (such as dry conditions, or lack of food), making it necessary for the larvae to remain in the water.
Neotenic “terrestrial” salamanders continue breathing through their gills, just like the larvae, even after they mature into adults.
Salamanders Do Not Need as Much Oxygen as We Do
Salamanders are ectothermic (cold-blooded) animals, which means they can not control their body temperature. Instead, their body temperature changes with that of their surroundings.
This is in contrast to endothermic (warm-blooded) creatures, like humans, which can maintain a constant body temperature by producing their own internal, body heat.
To make this heat, warm-blooded animals need food and oxygen. When the temperatures get colder, they will need more oxygen and more energy to produce body heat.
Since salamanders are cold-blooded, they do not use any oxygen to generate internal body heat. This means, their oxygen needs are not as high as those of warm-blooded animals.
In the winter, salamanders will brumate (hibernate) to protect themselves from the freezing temperatures. During brumation, their heart rate, breathing rate, and overall metabolic rate will dramatically drop.
Brumating salamanders will have extremely low oxygen needs because their bodies use very little energy.
Question: Can All Salamanders Breathe Underwater?
Answer: Most terrestrial salamanders have the ability to breathe underwater through their skin. This ability is limited to varying degrees depending on the species.
However, some salamanders such as the red-backed salamander live a fully terrestrial life (without an aquatic stage) and cannot absorb oxygen in the water through their skin.
Question: How Do Salamanders Drink Water?
Answer: Salamanders and other amphibians do not drink water through their mouths as we do. They absorb water through their permeable skin, just like they absorb oxygen during cutaneous respiration.
There are lots of different salamander species, so the exact way a salamander will breathe will depend on the species. Most salamanders start their lives as aquatic larvae that breathe through their gills.
As they transform into adults, salamanders such as the tiger and the marbled salamander develop lungs for breathing air.
However, other salamanders such as the red and the red-backed salamander do not develop any lungs as adults. Instead, they develop to breathe entirely through their skin and membranes in their mouth and throat via cutaneous respiration.
Aquatic salamanders usually have gills which they use to breathe in the water, but some also have functional lungs. Aquatic salamanders such as the hellbender do not have gills mostly breathe underwater through their skin.