Many people know that frogs love to spend a lot of their time in streams, ponds, and other water bodies. But how long can frogs stay underwater?
Frog tadpoles (baby frogs) have gills and can stay underwater almost indefinitely. As adults, frogs lose their gills and can only stay underwater for a limited time. Depending on several factors, most frog species can stay underwater anywhere from 4 to over 7 hours.
During the winter, some frog species such as leopard frogs will hibernate underwater and can stay submerged all winter long. They can stay submerged for so long because they breathe underwater through their skin.
Dissolved oxygen in the water that comes in contact with their skin is diffused into their bloodstream, and carbon dioxide is released from the bloodstream into the water (more information on that below).
Tadpoles Can Stay Underwater for an Unlimited Time
Frogs start their lives as tiny tadpoles. Tadpoles are very different from adult frogs; this is because they’re adapted for a fully aquatic life (life in the water), while adult frogs are adapted for a mostly semi-aquatic life (life on both land and in the water).
Tadpoles have external gills and a flat paddle-like tail fin for life in the water. They use their gills to breathe underwater, just like fish.
The gills have thin membranes and a network of blood vessels. These membranes absorb dissolved 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 gaseous exchange allows them to stay underwater almost indefinitely.
Sometimes, Tadpoles Need to Breathe Air
Tadpoles sometimes live in water with low oxygen levels – where their gills (and skin) cannot absorb sufficient oxygen. This means they also need to breathe air. For this reason, most tadpole species also develop lungs in addition to their gills.
When they first hatch, the tadpoles are too feeble to break through the water’s surface for a gulp of air. To get around this, they “bubble-suck”.
To do this, they first stick their open mouths to the underside of the water’s surface. They then open their jaws wide and suck at the water’s surface. Doing this creates an air pocket that they can pinch off by quickly closing their jaws.
After they close their mouth, a portion of the fresh air bubble is forced down into their lungs
Since the tadpoles are tiny, they usually cannot absorb the entire air bubble, and the excess is burped out as a small bubble, after which it floats back up to the water’s surface.
Once the tadpoles get bigger, they will be strong enough to break through the water’s surface for a gulp of air.
Tadpoles Turn Into Froglets
After a period of 2 to 3 weeks to as long as over 3 months (depending on the species), the tadpoles go through a process known as metamorphosis. In this process, they lose their larval features and develop their adult features.
During this process;
- They lose their gills and get well-developed lungs for breathing air
- The tail shortens and is eventually absorbed into the body
- They develop strong legs for moving on land
Once this process is complete, tiny froglets (small frogs), typically half an inch long will leave the water for a terrestrial life.
These froglets will grow into adult frogs and once they mature, they will typically go back to the water where they can breed and lay their eggs.
Adult Frogs Can Only Stay Underwater for a Limited Time
Unlike tadpoles, adult frogs do not have gills. They breathe using their lungs and by absorbing oxygen through their skin.
While underwater, they can not breathe with their lungs, so they have to hold their breath and breathe entirely through their skin (cutaneous respiration).
Dissolved oxygen in the water that comes in contact with their skin is diffused into their bloodstream, and carbon dioxide is released from the bloodstream into the water.
However, this method of breathing usually does not give frogs all the oxygen they need, so they can only be submerged for a limited time before they have to resurface to breathe air with their lungs.
How Long a Frog Can Stay Underwater Is Mainly Dependent on 4 Factors
How long a frog can stay underwater is mainly dependent on 4 factors, namely: how much dissolved oxygen there is in the water, the temperature, the frog species, and how active the frog is.
Depending on these factors, most frogs can stay underwater from a few minutes up to several hours at a time.
1. How Much Dissolved Oxygen Is in the Water
Frogs can stay submerged in water with a high oxygen content for much longer than they can in water with low oxygen content. The oxygen content of the water is affected by several factors including the following:
- The Nature of the Water
Oxygen from the air is dissolved in water at its surface, mostly through turbulence (for example waves, riffles, water tumbling over rocks, etc). For this reason, fast-moving water (such as a stream) will have a higher oxygen content than stagnant water.
If water is very stagnant, oxygen only dissolves on the water’s surface, and anything below the upper layer of the water will have a low oxygen content.
- Presence or Absence of Aquatic Plants and Algae
Aquatic plants and algae also affect how dissolved oxygen is in a body of water. During the daylight hours, they produce oxygen through photosynthesis and release it into the water.
At night, aquatic plants and algae will use up dissolved oxygen in the water via aerobic respiration and release carbon dioxide into the water.
For these reasons, the concentrations of dissolved oxygen in water with lots of photosynthesizing aquatic vegetation will be highest in the mid-to-late afternoon when photosynthesis rates are greatest and will reach the lowest concentrations just before the sun rises the next morning.
- How Much Dead Matter /Waste Is the Water
Water with lots of decaying plants and other organic matter (Sewage, yard waste, etc) 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.
- Altitude/Atmospheric Pressure
Water at lower altitudes can hold more dissolved oxygen than water at higher altitudes. With rising altitude, the atmospheric pressure decreases – hence less oxygen can dissolve into water.
For this reason, water at higher altitudes typically has less dissolved oxygen than water at lower altitudes.
- The Concentration of Dissolved Salts Present in the Water (Salinity)
Water with a high mineral content (high salinity) can hold less dissolved oxygen than water with a low mineral content (low salinity).
2. Temperature
Frogs and other amphibians are ectothermic (cold-blooded) animals, so the environmental temperatures will affect their rate of metabolism. At higher temperatures, they will have a higher metabolic rate, meaning they have a greater oxygen demand.
At lower temperatures, the opposite is true. Frogs will have a lower metabolic rate meaning they have a lower oxygen demand.
Also, the temperature will affect the oxygen content of the water. More oxygen will dissolve into cooler water than into warmer water.
All this combined means frogs can stay underwater at lower temperatures for much longer than they can at warmer temperatures.
3. Species/Skin Surface Area
Tadpoles have gills that provide a very large surface area to absorb lots of oxygen from the water. However, as adults, frogs do not have gills, so how much oxygen they can absorb from the water depends on their skin surface area.
Some frog species have a very large skin surface area and are better at absorbing oxygen from the water than others.
For example, the Titicaca water frog is an aquatic frog species with wrinkled skin. This frog’s excessive amount of skin makes it look rather as if it were wearing an oversized wet suit. But it performs a very important function – it provides a bigger surface area to use for cutaneous respiration.
For this reason, the Titicaca water frog can live in water with a low oxygen content where most frogs wouldn’t make it. They have even been recorded diving to a depth of 400 feet!
Because of their large skin surface area, these frogs do not need to surface regularly to breathe and can stay submerged for several days in water with a high oxygen content.
4. How Active the Frog 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 frogs, 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.
For this reason, frogs will be able to underwater when at rest, for much longer than they can when they are very active.
Can Frogs Drown?
Even with their ability to breathe underwater through their skin, frogs can drown. Frogs have lungs, and If their lungs fill with water, they can drown.
The oxygen they absorb through their skin is usually not enough to meet all their oxygen needs for long, so they can only stay submerged for a limited time before they will have to surface to breathe air with their lungs.
If a frog dives into water so deep that it can not surface for air in time, it will drown.
Some Frogs Stay Underwater All Winter Long
As mentioned earlier, frogs are ectothermic (cold-blooded) animals, so their body temperatures take on the temperature of the surrounding environment.
Frogs and toads are cold-blooded, so their body temperatures take on the temperature of the surrounding environment. During the winter, they go into a state of hibernation/brumation to protect themselves from freezing temperatures.
Frogs that spend most of their time on land will hibernate in burrows below the frost line, inside deep cracks in rocks or logs, under thick leaf litter, and in compost heaps.
Frogs that spend most of their time in or near water (such as leopard frogs) will typically hibernate underwater.
However, not just any pond will do, the pond needs to be deep enough so it does not freeze all the to the bottom. It also needs to have lots of dissolved oxygen so the frog can efficiently breathe underwater all winter long.
Unlike many animals that hibernate underwater, frogs do not dig into the mud at the bottom of ponds or streams. Since they breathe entirely through their skin during underwater hibernation, they would suffocate if they were dug into the mud for an extended period.
Hibernating frogs must be near oxygen-rich water and spend a good portion of the winter just lying on top of the mud or only partially buried. They may even slowly swim around from time to time.
Some Frogs Are Almost Fully Aquatic
Some species of frogs spend nearly their whole lives underwater. The African Clawed Frog and Green Puddle Frog are just two examples of frog species that rarely leave the water.
These frogs are highly adapted for life in the water and can stay submerged for a very significant amount of time, especially in water with a high oxygen content.
The Frog Without Lungs
The endangered Bornean Flat-Headed frog found in Indonesia is the only currently known species of frog that does not have any lungs at all! It breathes entirely via its skin, just like many lungless salamanders.
This aquatic frog lives in cold, fast-moving rivers that provide a rich supply of oxygen and most likely lower the frog’s metabolic rate. So to the frog, oxygen is in high supply and low demand.
Also, the flattened body and head (which gives this frog its name) give its skin a large surface area for absorbing oxygen from the surrounding water.
For these reasons, Bornean Flat-Headed frogs can stay submerged almost indefinitely.
Frequently Asked Questions:
Do Frogs Have Gills? Frogs have gills as tadpoles. However, with time, the tadpoles will go through the process of metamorphosis in which they will lose their gills and develop functional lungs as they grow into froglets. Mature adult frogs do not have gills.
Can frogs live underwater? Aquatic frogs spend most of their time underwater and very rarely leave the water. However, this is no known frog species that lives entirely underwater without ever surfacing or leaving the water.
How long can toads stay underwater? Toads are a type of frog, so they can stay underwater for the same amount of time most frogs can. However, toads generally live more terrestrial life than most true frogs, so they are not as adapted for life in the water. As a general rule, most toads can stay underwater for about 5 to 20 minutes at a time (depending on several factors).
Final Thoughts
Frogs are semi-aquatic animals, which means they spend part of their lives on land, and part in the water. They start their lives as tadpoles with gills for breathing underwater. At this stage of their life, frogs (tadpoles) can stay underwater for as long as they can get enough oxygen through their gills.
Over time, the tadpoles will transform into froglets through the process of metamorphosis. During this process, they lose their gills and develop functional lungs.
Once fully transformed, the froglets will leave the water for a life on land. Adult frogs breathe by using their lungs and absorbing oxygen through their skin and thin membranes in their mouths and throat.
When underwater, they breathe entirely by absorbing dissolved oxygen in the water through their skin. This does usually 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.
However, during hibernation, they have extremely low oxygen requirements which can easily be met through cutaneous respiration (breathing through the skin), enabling some frog species to stay submerged all winter long.
