Frogs belong to the amphibian group. The word "amphibian" comes from the Greek and means “ double life ” (amphi=double, bios=life). This name is due to a particular characteristic of this group of animals: they live the first half of their life in the water, and the second half of their life on land. Within amphibians, and together with toads, frogs belong to the order anura (which are amphibians that lack a postcloacal tail).
How do frogs breathe?
Before clarifying where frogs breathe, it is important to know how they breathe. As we will see below, frogs present various types of respiration throughout their lives. The main frog respiration are:
- Gill Respiration
- Lung Respiration
- Skin respiration
Next, we will discuss each of these types of respiration in frogs. If, in addition to frogs, you are interested in amphibians in general, you can take a look at this other article on our site about Where and how do amphibians breathe?
Gill respiration in frogs
Have you ever wondered how frogs breathe in water? In their larval state, anurans have external gills that allow them to breathe through gas exchange with water Water enters through the mouth and exits through the gill slits, where gas exchange takes place thanks to the capillary vessels associated with the filaments that make up the gills.
In parallel, internal gills develop below where the external ones were located. A few days after life, through metamorphosis, the external gills are covered by a tissue fold called the operculum, which leaves only one or two small openings to the outside called spiracles. From this moment on, the larvae begin to use the internal gills for gas exchange and, in the last stages of their metamorphosis, they lose these gills and develop lungs
Now that you know how tadpoles breathe, discover more Animals that breathe through gills here.
Lung respiration in frogs
During their adult stage, frogs have two lungs and no diaphragm, so they must make convulsive movements with their throat to generate air inlet and outlet. Lung respiration in most frogs occurs through a mouth pump in two steps:
- Initially, the oral cavity is opened by contractions of the oral floor, generating fresh air loaded with oxygen to enter from outside.
- At the same time that the oral cavity is opened, the lungs are compressed expelling the gases already used, which have little oxygen load.
Part of this used gas is released back into the environment through the nostrils, and another part is mixed with the air just entered the oral cavity. Of this mixture, a part returns to the atmosphere through the mouth, and another part goes to the lungs. Exhalation is caused by an elastic recoil of the walls of the body and the lungs.
Cutaneous respiration in frogs
However, there is a third mode of breathing in these animals, which accompanies them throughout their entire lives: the skin respiration. That's right, they also breathe through their skin! Amphibian skin is highly permeable and vascularized, allowing oxygen to pass from the surface to the blood. In addition, they have glands that secrete a mucus that keeps them moist, which facilitates gas exchange.
Conservation problems
The fact of presenting a type of cutaneous respiration requires that the skin of the frogs be widely permeable, which makes them very sensitive to the conditions of their environment. They are vulnerable to pollution, making them excellent indicators of the state of their environment. This characteristic also makes them vulnerable to dehydration due to increased temperature. These factors are some of the main causes that explain the phenomenon called “ Global Decline of Amphibian Populations”, which announces that this is one of the most affected in terms of biodiversity loss caused by the changes that our planet has been undergoing in recent years.
However, not only frogs breathe through their skin, but there are many more skin-breathing animals. If you want to know them, take a look at this other article on our site about Animals that breathe through their skin.
Frogs without lungs
As in all animal groups, each species has its own ecological characteristics, which leads them to present different adaptations according to their lifestyles. Thus, there is variability in the breathing mechanisms of each species.
The most extreme case is that of the species Barbourula kalimantanensis, which lacks lungs and uses only skin respiration. This species has folds in the skin, which increase the gas exchange surface.
