Life cycle of the frog phases and their characteristics (with images)

Abraham McLaughlin
Life cycle of the frog phases and their characteristics (with images)

The life cycle of frogs It consists of all the phases or stages that these animals go through from the moment of their birth to their death. In most frogs, this process has the peculiarity that it takes place between two different environments: water and land..

When frogs are born, they live in water throughout their entire stage. youth. In this stage, frogs are very similar to fish, and are known as tadpoles. As tadpoles grow in size and develop, they begin to develop walking legs.

These legs help them to walk and move when they finish their development. When their legs are fully developed, the "tadpoles" leave the aquatic environment and go on to live on land..

Although adult frogs live mainly on land, they always depend on nearby bodies of water (such as lakes, ponds, rivers, or ponds) so that they can stay hydrated, get food, and also reproduce..

Stages of the frog life cycle

The life cycle of frogs can be defined in 4 different stages, during which these animals undergo an incredible metamorphosis, almost comparable to that of butterflies, for example. These stages are:

- the egg

- the tadpole

- the young frog

- the adult frog

The metamorphosis It is the process of change by which frogs change their physical aspects and their physiological characteristics considerably. These changes are necessary to colonize the land after having led a life in water..

Some textbooks may omit or add more life stages to this small list, however, they always refer to the same ones that we will explain below..

1- Eggs

Photograph of frog eggs (Source: Fanghong, via Wikimedia Commons)

Frog eggs typically have a jelly-like, translucent appearance, like a kind of jelly “ball”. However, the appearance of the eggs can vary greatly depending on the species of frog..

Female frogs produce eggs inside their bodies, but only if the eggs come into contact with the sperm of a male frog (fertilization) can they give rise to viable eggs and form new frogs.

Adult frog with eggs

In frogs, fertilization is external. This means that the females release the eggs through a hole in the back of their body, at which point the male mounts on top of the female and releases the sperm at the same time..

As soon as the female's eggs come into contact with the male's sperm, the eggs are fertilized by the male's sex cells and embryos begin to develop inside them that will become new frogs..

Frog eggs are very permeable to environmental pollutants, which is why they are extremely sensitive to environmental pollutants..

2- Tadpole

Photograph of a tadpole (Source: LiquidGhoul, via Wikimedia Commons)

When the embryos have developed properly, the newly hatched "frogs" emerge from the interior of the egg as small larvae known as "tadpoles.".

Physically and physiologically, at that time, tadpoles are very similar to fish, even sometimes they are difficult to differentiate.

Tadpoles have a front part that is made up of a large head. The head is followed by a slim body, with small fins on each side, and a long rear tail that helps them swim..

Group of legless tadpoles

Like fish, tadpoles have gills to breathe underwater, since they inhabit the water of lakes, ponds, puddles, rivers, etc..

Tadpoles are usually voracious predators of algae, as their growth and development is directly dependent on the amount of food they consume. It is estimated that, on average, a tadpole can feed a day on its same weight in algae, and that is a lot.

Over time, the tadpoles increase in size and begin to absorb the gills into their bodies, as these will transform into the lungs of the adult frogs. In addition, they begin to develop legs on the sides of the tail and then in the middle of the body.

2-legged tadpole

The circulatory system of the tadpole also undergoes great changes, which are necessary to be able to oxygenate the blood in the lungs (in the terrestrial environment) instead of oxygenate the blood through gills (in the aquatic environment).

3- Young frog

Young frog

Young frogs possess almost all the physical characteristics of fully developed (adult) frogs. However, young frogs sometimes still have tails, are smaller than adult frogs, and their skin is very thin and sensitive..

In the short time that they remain as young frogs, the tail disappears, progressively decreasing in size, until it disappears completely..

In this phase, frogs have already developed a large mouth, lungs and legs (back and front), but they do not have the ability to permanently breathe oxygen from the air, nor do they have much skill with their legs to move around the earth's surface..

During this stage, the young frogs begin to hunt small insects for food and they depend less and less on the consumption of algae..

Although this growth stage is usually very short, many researchers consider this stage to be different from that of an adult frog, as they do not exhibit the typical behavior seen in adults..

4- Adult frog

Photograph of an adult frog with detailed webbed feet (Source: Rushenb, via Wikimedia Commons)

Adult frogs have well-developed, thick skin, often with warts and bumps. They have well-developed four legs, which they use to move with great leaps on the ground.

In addition, the legs serve to swim very efficiently, since they have webbed feet (they have membranes between the toes), specially designed for swimming..

Group of adult frogs

In adult frogs, the vocal cords, lungs and special cartilage in the mouth are highly developed to make sounds. Using these structures, frogs can communicate at great distances with each other.

These sounds are also used to warn other frogs about the presence of predators, to attract mates or simply to communicate with other frogs in the same environment..

Adult freshwater frog

The vast majority of frog species take 10-12 weeks to reach maturity from hatching. However, this time depends on the species of frog, the conditions of the environment and the food available in it..

On average, frogs can live between 5 and 10 years, but some species can live up to more than a decade. During this stage they constantly feed on insects and small vertebrates.

Themes of interest

Hummingbird life cycle.

Butterfly life cycle.

Turtle life cycle.


  1. Hickman Jr, C. P., Roberts, L. S., & Larson, A. (1993). Integrated Principles of Zoology. IX ed. Mosby-Year Book. Inc., St. Louis.
  2. Hickman, C. P., Hickman, F. M., & Kats, L. B. (2000). Laboratory Studies in Zoology. McGraw-Hill Science / Engineering / Math.
  3. Mayer, M., & Mayer, M. (1977). One frog too many. Puffin books.
  4. Royston, A. (2009). Frog (Vol. 16). Capstone Classroom.
  5. Suzuki, D., & Tovell, V. (1987). Metamorphosis: Stages in a life. Stoddart.

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