Tadpole Definition & Life Cycle

Chelsie Wheeler, Julie Zundel
  • Author
    Chelsie Wheeler

    Chelsie has been a private tutor and a peer mentor throughout her ten-year career as an environmental and fisheries biologist. She also has experience educating the public through various programs via outreach with presentations, festivals, and set courses. She has a bachelor of science degree in environmental management from Columbia Southern University and a master of science degree in coastal and marine environments from the University of Ireland, Galway.

  • Instructor
    Julie Zundel

    Julie has taught high school Zoology, Biology, Physical Science and Chem Tech. She has a Bachelor of Science in Biology and a Master of Education.

Learn what a tadpole is and explore the tadpole life cycle, discovering how long it takes a tadpole to develop into an adult frog. Updated: 12/24/2021

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What is a Tadpole?

What is a tadpole? A tadpole is the larval stage of the amphibian life cycle. There are many different amphibians that have tadpoles in their life cycle; however, the most common is a frog. This lesson focuses on tadpoles within the average life cycle of frogs. Depending on the species of frog, each phase in the life cycle may be slightly different than what is considered average.

What do tadpoles look like? Tadpole larva once hatched develop a tail to help them swim in the water. Tadpoles tend to look like an oval-shaped head with an attached tail. The colors of tadpoles change drastically depending on the species and can be anywhere from dark black to bright red! When tadpoles first hatch, they only have small eyes, nostrils, body, tail, and a vent which leads to internal gills.

Tadpoles are different from many other animals in that the young do not look like miniature versions of the adults. Tadpoles must undergo a special process known as metamorphosis, a process that changes an organism abruptly from a larval form into the adult form.

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  • 0:04 What Is a Tadpole?
  • 0:56 The Tadpole Stages
  • 3:14 Lesson Summary
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Tadpoles develop from their larval state, seen in image A, and undergo metamorphosis to become an adult, seen in image E.

tadpole 1

Tadpole Life Cycle

There are seven main stages in tadpole development. Tadpoles are the larval stage in the tadpole life cycle; however, this particular life stage can be broken down into hatching, free swimming, teeth, and legs to help better highlight the stages and importance of how tadpoles grow. The four broad stages are sometimes used to sum up a frog's life cycle. These four broad stages are egg, tadpole, froglet, and frog.

Tadpole Stages Significance
Eggs The first stage in the tadpole lifecycle, when a frog is created and develops before it hatches.
Hatching The second stage in the tadpole lifecycle is when the tadpole emerges from the egg and enters the tadpole larval stage.
Free Swimming Once the tadpole enters the larval stage, it begins to swim and consumes organic matter.
Teeth After consuming soft organic matter, teeth help to broaden the tadpole's diet to include a wider array of foods.
Legs Legs signal the beginning of the metamorphosis process when the tadpole leaves the larval stage and becomes an adult.
Froglet The final stage in the metamorphosis process before the tadpole becomes a mature adult and slowly loses the tail.
Frog Usually shown by the absence of a tail and metamorphosis is complete. The adult frog is sexually mature, meaning it can produce offspring.

The life stages of a green frog, starting with a fertilized egg and ending with an adult frog.

tadpole 2

Life Stages Timeline for Tadpoles

Eggs Hatching Free Swimming Teeth Legs Froglet Frog
6-21 days to hatch → 0-21 days after hatching → 1-4 weeks after hatching → around 4 weeks after hatching → 5-9 weeks after hatching → 12 weeks after hatching → roughly 13-16 weeks after hatching

Eggs

Female frogs will lay eggs in large clusters which are fertilized by males as they are laid. Typically, hundreds of eggs are laid and fertilized simultaneously to increase the change of some tadpoles making it to adulthood. There are two layers of a protective gelatinous membrane, one layer covers the entire cluster of eggs while the second layer covers each individual embryo for protection. The fertilized cells will begin to divide immediately to create a zygote which will eventually become an embryo. The jelly-like membrane helps to feed and protect the embryo as it grows.

A cluster of frog eggs surrounded by a gelatinous protective coating, which also covers each individual egg.

tadpole 3

Hatching

The hatching period happens generally between 2-21 days after fertilization. Unlike other organisms that hatch from eggs, aquatic species that hatch typically do not shed their gelatinous egg coating. Instead, they emerge through an opening in the membrane and absorb the nutrients from the egg yolk by keeping it attached to their bodies. During this time, they typically stay somewhat stationary while they learn to swim through the water. In most cases, a tadpole will affix itself to weeds immediately after hatching from an egg. While they remain still, they are still growing and developing muscles to become stronger and more fit, which increases their survival rate tremendously. The yolk acts as a feeding source until their mouths, teeth, and jaws develop to better provide sustenance.

Tadpoles, shortly after hatching, affix themselves to grass so they can absorb their egg yolks and become stronger.

tadpole 4

Free Swimming

Once hatched, the tadpole will contain an individual head and tail which is connected by a torso. The head is made up of eyes and a mouth along with several specialized characteristics that will change after metamorphosis. External gills will migrate inside, pits located on the face will become nostrils, and the tail will eventually disappear. At first, the tadpoles do not look like adult frogs. Unlike most animal species, frogs, like some other amphibians, have a larval state and then must undergo metamorphosis to enter into the adult phase of their life cycle. It is not until they have gone through metamorphosis that the tadpoles really look like frogs.

Tadpoles in the free-swimming phase of their life cycle.

tadpole 5

Teeth

The tadpole will develop teeth anywhere from 1-4 weeks after it hatches. Teeth develop at this time to help the tadpole consume different types of organic matter such as insects. At this time tadpoles begin to develop their social skills and learn traits they will need for adulthood.

Legs

Hind legs will develop first and this is often known as the frogs with legs stage in the tadpole life cycle. Most tadpoles start to develop legs 5-9 weeks after hatching. At the same time many of the different specialized characteristics that helped the tadpole survive, such as exterior gills, will change during metamorphosis. Lungs start to develop to help adult frogs breathe on land; however, some frogs still retain interior gills into adulthood to help them breathe underwater. Most amphibians also breathe through a process called cutaneous respiration, which means they respirate through their skin!

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Frequently Asked Questions

How long does it take for a tadpole to turn into a frog?

For a tadpole to turn into a frog it must undergo the seven main stages in tadpole development. While this timeline varies between species, on average it takes around 14 weeks for a tadpole to turn into a frog.

How long does it take for a tadpole to become a frog?

The length of time it takes for a tadpole to develop into a frog depends on the species, but on average it is about 14 weeks.

What are the stages of a tadpoles life?

There are seven main stages in tadpole development. These include (1) eggs, (2) hatching, (3) free swimming, (4) teeth, (5) legs, (6) froglet, and (7) frog.

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