How Do Frogs Breathe?

Frogs are fascinating animals that can live in water and on land. Because of their amphibious lifestyle, I often get asked how frogs breathe, especially underwater, underground, or during hibernation (brumation).

Frogs breathe using their gills and skin as tadpoles, and via their skin and lungs as adults. Frogs may intake oxygen and expel carbon dioxide through their skin (cutaneous respiration), or lungs using their nostrils, mouth, or mouth lining.

Frogs lose their gills and fully develop lungs at the froglet stage allowing them to live on land or in water.

Illustration of how frogs breathe

If you have ever been curious about the way a frog breathes, keep reading. Below, you will find interesting information on frog respiration, as well as when and why they may choose a certain type of respiratory method.

Frogs Breathe Through Their Skin

Frogs have thin, permeable skin allowing them to carry out cutaneous respiration thought their life cycle. Frogs can take in oxygen and expel carbon dioxide via their skin or lungs as adults.

Frogs can breathe through their skin thanks to a wide amount of blood vessels that enable the porous exchange of gasses through osmosis.

During the breathing process, oxygen is diffused through the thin membranous tissue of the skin and absorbed into the blood vessels.

Illustration of how frogs breathe through osmosis (cutaneous respiration)

The same process is used to release carbon dioxide from the frog’s body. The action is further encouraged thanks to the mucus coating and glands on the outer layer of the frog (CTNF).

Frogs must always have moist skin in order to remain hydrated and absorb dissolved oxygen from the air. This is the main reason why aquatic frogs remain in freshwater most of the day, and toads stay out of the sun and spend most of the day underground.

How Frogs Breathe

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Aquatic frogs remain in cold, oxygen-rich water during hibernation and toads burrow underground. During that time, frogs cannot rely on their lungs to breathe or they could drown or suffocate.

Therefore, frogs primary rely on cutaneous respiration during the months when they hibernate or estivate.

Frogs have inefficient lungs and would suffocate if they only relied on their lungs to breathe. This is a main reason why frogs are considered excellent bio-indicators of their ecosystems. Frogs are extremely sensitive to polluants, salts, and other chemicals in their surrounding environment.

Frogs Can Breathe Through Their Lungs

Frogs generally only breathe through their lungs when necessary since their lungs are poorly developed.

A frogs lungs are very useful to help them breathe on land, however, they are not strong enough to handle the complete respiratory needs of frogs. Therefore frogs also need to breathe through their skin to cover their respiratory needs.

The process frogs use for pulmonary respiration is similar to mammals. Frogs intake air through the nostrils, mouth (buccopharyngeal respiration), or mouth cavity which is distributed into the lungs.

However, frogs do not have ribs or a diaphragm to help store the air, so to expel carbon dioxide though their lungs they forcefully contract their throat.

Illustration of how frogs breathe on land

Frog mouths contain a moist lining that is extremely permeable. When a frog is not entirely submerged in water, it can rely on its mouth to take in oxygen and release carbon dioxide.

Because they have lungs, adult frogs can drown if their lungs fill with water, but also if there is not enough oxygen in the water, the water is polluted or contains too much nitrate, or if their skin is dried out to the point it cannot absorb water or oxygen.

For these reasons, the frog needs to find a safe location with clean oxygenated water to live. It should not be without moisture for excessive periods either, or it will essentially dry out and be unable to breathe.

Can Frogs Breathe Underwater?

Frogs can breathe underwater through their skin and gills as developing tadpoles, and through their skin and lungs as froglets and adult frogs.

As tadpoles, frogs are fully aquatic and breathe underwater through gills. Frogs initially have internal gills and develop external gills around 6 weeks into their development (depending on the species and environment).

Tadpole Stage 1-min
Tadpole with external gills
Tadpole Stage 2-min
Tadpole with internal gills
Tadpole Stage 3-min
Froglet developed lungs

Frog tadpoles use their gills take in oxygen as water passes over them, somewhat like fish.

Through the process of metamorphosis, tadpoles absorb their gills as they grow older. After around 12 to 16 weeks, most frog species have developed lungs and no longer have gills.

Tadpoles have gills that allow them to thrive underwater, but prevent them from living on land. However, adult frogs cannot breathe underwater since they have lungs. If a frog’s lungs fill with water, the frog can drown.

An adult aquatic frog I found breathing in water on a summer day

As a general rule, most non-fully aquatic frogs can live 4 to 5 months in underwater or in mud when they are hibernating. During the Summer, they can spend hours submerged with their head above water breathing through their nostrils and skin.

However, during hibernation, aquatic frogs slow down their heart rate and primarily breathe through their skin absorbing oxygen in their surrounding environment.

During the rest of the year, frogs can remain underwater for short periods of time to hide or swim, but cannot rely on their lungs to breathe below water.

However, fully aquatic frogs such as Titicaca Water Frogs, African Dwarf Frogs, and African Clawed Frogs can live underwater 24/7 since they are fully aquatic. Another aquatic frog species known as the “Hairy Frog” developed hair-like structures on its skin to intake more oxygen while living underwater.

This ability stems back from the frog’s uniquely designed body and respiratory system. Since the frog uses its skin and mouth to breathe in and out of the water, it can easily stay hydrated and oxygenized for long periods of time.

Questions About How Frogs Breathe

Do toads breathe through their skin? Toads breathe through their skin and can also breathe through their lungs and nostrils. As tadpoles, toads breathe through their gills which they lose as toadlets.

How do frogs breathe? Frogs breathe using their gills and skin as tadpoles, and via their skin and lungs as adults. Frogs may intake oxygen and expel carbon dioxide through their skin (cutaneous respiration), or lungs using their nostrils, mouth, or mouth lining.

Can frogs breathe underwater? Frogs can breathe underwater through their skin and gills as developing tadpoles, and through their skin and lungs as froglets and adult frogs.

Why can frogs breathe through their skin? Frogs can breathe through their skin because it is thin, porous, and contains a wide amount of blood vessels that enable the porous exchange of gasses through osmosis. Oxygen is diffused through the thin membranous tissue of the skin and absorbed into the blood vessels.

Sources

Chesne, Corinne. La Grenouille. Artémis éd., 2009.

Parsons, Harry. L’univers Des Grenouilles: Amphibiens Poseurs. Éditions Du Trécarré, 2000. 

Grenouilles, Crapauds Et Rainettes: Morphologie, Comportement, Alimentation Et Reproduction …, by S. Caratozzolo, De Vecchi, 2008.

Daniella Master Herpetologist

Daniella is a Master Herpetologist and the founder of toadsnfrogs.com, a website dedicated to educating the general population on frogs by meeting them where they are in their online Google Search. Daniella is passionate about frogs and put her digital marketing skills and teaching experience to good use by creating these helpful resources to encourage better education, understanding, and care for frogs.