Newts are semi-aquatic animals, which means they live both on land and in the water. They have different ways of breathing in each of these unique environments. On land, they breathe using their lungs, just like us. In the water, they breathe through a process known as cutaneous respiration (breathing through the skin).
Newts can breathe underwater by absorbing oxygen that comes in contact with their skin. Their skin contains thin membranes and a large network of blood vessels, which allows oxygen dissolved in the water to diffuse directly into their bloodstream.
The oxygen they get from this is usually insufficient, so they can only stay underwater for a limited amount of time before they have to surface for a gulp of air.
However, when they are inactive (such as during hibernation), they can get all the oxygen they need through their skin allowing them to stay underwater all winter long.
How Newts Breathe at the Different Stages of Their Life Cycle
Most newts go through 3 distinct life stages: Aquatic larvae stage, terrestrial juvenile stage, and semi-aquatic adult stage.
They start as tiny aquatic larvae with gills. The larvae then go through a process known as metamorphosis and transform into juveniles (also called efts), able to live on land. After a few months, the larvae mature into adult newts.
During these different life stages, newts have different ways of breathing.
How Newt Larvae Breathe
Female newts lay jelly-covered eggs and attach them to vegetation in breeding bonds. Some newt species even wrap leaves around the eggs, to hide them from predators. After a few months, tiny newt larvae emerge from these eggs.
The larvae are very different from adult newts. They have feathery gills protruding from the sides of their head, a flat tail fin, and live entirely in the water.
The larvae gills have thin membranes and a network of blood vessels. These membranes absorb oxygen from the water and move it into the bloodstream. At the same time, carbon dioxide from the bloodstream passes out through the membranes, and into the water.
This allows newt larvae to breathe underwater, just like fish.
Larvae Turn Into Juveniles
After a few months, the larvae go through a process known as metamorphosis, in which they lose the features that help them live in the water, and develop features for a life on land.
During this process,
- Their gills are absorbed into their head, and they develop lungs for breathing air
- They develop strong legs for walking on land
- Their flat tail becomes more rounded
Once they are fully metamorphosed, they use their lungs to breathe air. They live entirely on land hiding under stones, logs, fallen leaves, and other natural covers in the environment.
How Adult Newts Breathe
After a few months, to as long as several years (depending on the species), the juveniles will mature into adult newts. At this stage, the newts will be semi-aquatic, meaning they will live both and land and in the water.
Where they will spend most of their time depends on the specific species of newt. Some newts, such as the rough-skinned newt and the smooth newt will spend most of their lives on land, only returning to the water to breed.
While other newts, such as the eastern newt will spend most of their adult lives in the water, rarely going on to land.
Adult Newts Use Their Lungs to Breathe Air
Adult newts breathe air using their lungs. However, their lungs are quite primitive when compared to our own. They do not have diaphragms to push air into the lungs, so they rely on what is known as Gular pumping.
They suck air into their mouth and nostrils, then push the air into the lungs by raising the floor of the mouth, contracting their throat. To breathe out, they simply reverse this process.
They Can Also Breathe Through Their Skin
However, breathing this way is inefficient, so they also breathe through their skin to get extra oxygen. This is known as cutaneous respiration. Their skin has very thin membranes large network of blood vessels very close to the surface. This membrane allows oxygen to diffuse directly into their bloodstream.
Underwater Breathing
When in the water, they can not use their lungs to breathe air. They breathe entirely through their skin. When the water comes in contact with their skin, oxygen dissolved in the water is diffused into their bloodstream, and carbon dioxide is released into the water.
However, this way of breathing cannot give them all the oxygen they need, so they can only stay underwater for a limited amount of time before they have to resurface and get a gulp of air.
How Long Can a Newt Stay Underwater?
The short answer is: It depends on the amount of oxygen in the water, and how much oxygen it can absorb through its skin.
The less oxygen it can absorb from the water, the less time it can stay underwater.
There are generally 4 factors that affect how long a newt can stay underwater: The temperature, the newt’s skin surface area, the nature of the water the newt is in, and how active the newt is.
Temperature
The temperature will affect the oxygen content of the water. More oxygen will dissolve into the water at colder temperatures, than at warmer temperatures.
In addition, the temperature affects the newts’ rate of metabolism. At higher temperatures, newts will have a higher metabolism and be more active, meaning they have a greater need for oxygen.
At lower temperatures, the opposite is true. They will have a lower rate of metabolism and be less active meaning they will have lower oxygen requirements.
All this combined means newts can stay underwater at lower temperatures for much longer than they can at warmer temperatures.
The Nature of the Water
Fast-moving or ‘stirred up’ water generally contains more oxygen than still water. This is because oxygen from the atmosphere mixes with the water easier. In still water, oxygen only dissolves on the water surface, so the deeper you go into the water the less oxygen there is.
In addition, water with lots of decaying plants will have a lower oxygen content. This is because the bacteria responsible for the process of decomposition use oxygen and release carbon dioxide into the water, reducing the oxygen content of the water.
The Newts’ Skin Surface Area
As larvae, the feathers on their gills provide a very large surface area, so newt larvae can absorb all the oxygen they need through their gills. However, as adults, the surface area of their skin is limited, so they can only absorb a limited amount of oxygen.
As a general rule, the greater the skin surface, the longer a newt can stay in the water. For example, in crested newts, that large crest provides an extra surface of the skin, enabling them to absorb more oxygen from the water.
How Active the Newt Is
Activity affects how much oxygen the body needs. Think about it, when we are running or jogging, we breathe heavier and in much quicker breaths than when we are at rest.
For newts, this is also true. They will have a higher oxygen demand when they are very active in the water (escaping a predator or chasing prey, for example), and a lower oxygen demand when they are inactive.
Depending on these 4 factors, newts can stay underwater anywhere from 5 minutes to several hours. However, during periods of inactivity, such as during hibernation, cutaneous respiration can meet their oxygen requirements enabling them to stay underwater all winter long.
Can Newts Drown?
Even with their ability to breathe underwater through their skin, newts can drown. The oxygen they get from the water is usually not sufficient, so if a newt gets into a water body so deep that it can not resurface to breathe air, it can drown.
In addition, several illnesses and infections can limit a newt’s ability to breathe its skin. This increases the likelihood of drowning.
Tips to Prevent Your Pet Newt From Drowning
If you have a pet newt, you must educate yourself on how to properly house your newt. Some newts, such as the sharp-ribbed newt or the paddle-tail newt will do well in a fully aquatic setup, with only a limited land area. However, others such as the rough-skinned newt will need a much larger land area.
Here are some tips to help you take good care of your newt and prevent it from drowning.
- For Mostly Terrestrial Newts, Create a Habitat With Two Distinct Areas: Land and Water.
Use a floating platform, or build a beach by filling one side of the aquarium with gravel until the gravel rises above the waterline. This way, your newt will be able to easily climb onto “land” when it wants to get out of the water.
- Regularly the Water in the Aquarium.
When a newt eats, the food is digested, then eventually released as waste. Oftentimes, the newt will release this waste into to water. Eventually, the waste accumulates both as solid debris, and as dissolved chemicals in the water. This poor water quality will negatively affect its oxygen content, limiting your newts’ ability to breathe underwater.
Regularly change the water in the aquarium. The frequency of the water changes will be determined by the size of the aquarium, and how many newts are housed in it.
The smaller the aquarium, the faster the waste will build up, and the more frequently you will have to change the water. Additionally, more newts mean more waste will be released into the water leading to a faster waste build-up.
Conclusion
Newts are semi-aquatic animals, which spend part of their lives on land, and part in the water. On land, they breathe by using their lungs and absorbing oxygen through their skin.
Underwater, they breathe entirely by absorbing the oxygen in the water through their skins, and into their bloodstream. This does not meet all their oxygen requirements, so they can only stay underwater for a limited amount of time before they have to surface to breathe.
If you have a pet newt, provide a good environment and lots of clean oxygenated water so it can breathe efficiently through its skin.
