life cycle of frog essay

IELTS Writing Task 1 Essay: The Life Cycle of a Frog

Updated On Oct 05, 2023

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Introduction.

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The Writing module of IELTS is divided into two parts – Task 1 and Task 2. Task 2 is the same for both IELTS Academic and IELTS General, and requires the candidate to write an essay.

On the other hand, Task 1 is different for the two types of exam. While for IELTS Academic, it is report writing based on graphs, charts, tables, diagrams and maps, for IELTS General, it is letter-writing.

Here, we have provided a sample answer with a report plan for the writing task 1 question – the life cycle of frogs. In your IELTS Writing Task 1 essay, you should:

Describe the different stages of the frog’s life cycle in chronological order.
Explain how the frog changes at each stage.
Use clear and concise language.
Support your claims with evidence from the diagram or other sources.

A sample answer for a Writing Task 2 essay is important because it can help you understand the requirements of the task, learn how to organize your essay, improve your writing skills and get an idea of the expected level of performance and band score.

Before going through the sample answer to learn the way the answer for the life cycle of a frog is written, check out the Academic Writing Task 1 Tips, Strategies and Criteria to solve this type of question.

– Begin your answer by paraphrasing the question with appropriate synonyms for the words in the question. – In the second paragraph, write the general information that the diagram provides. – Discuss the key elements shown in the first three steps of the diagram. – Discuss the major features shown in the second three steps of the diagram.

Sample Answer 1

The diagram demonstrates how a frog evolves throughout its life cycle from egg to adult.

Overall , it is evident that the process is divided into six separate stages, initiating with the production of eggs in the water and culminating with the maturation of a frog.

The frogspawn-like eggs that float on the water’s surface represent the first stage. After the frogspawn hatches from the embryo, the little tadpole emerges as the next stage. The little tadpole has a long tail and a small body at this stage in its life cycle. Next, the tadpole develops over time, as shown in three small steps, lengthening its tail and increasing the size of its body. Then, to prepare the tadpole for its future existence on land, the legs start to form simultaneously .

The tadpole subsequently begins to transition into a baby frog with a broader mouth, a shorter tail, and larger legs, despite continuing to live in water. Gradually , the frog gains maturity until it is ready to leave the water and walk onto land. Steadily , the tadpole frog loses its tail when on the ground and begins to breathe air. In this way , the life cycle for this frog is complete. Eventually , the adult frog needs to locate a mate to lay eggs and the lifecycle will restart for another frog to be born.

Sample Answer 2

The diagram illustrates the progressive transformation of a frog from its initial stage as an egg to its mature adult form.

In summary, it’s clear that this process consists of six distinct phases, commencing with the laying of eggs in the water and concluding with the full development of a mature frog.

The first stage is represented by frogspawn-like eggs that float on the water’s surface. Once these eggs hatch, they give rise to small tadpoles in the subsequent stage. At this point in their life cycle, tadpoles possess elongated tails and diminutive bodies. Subsequently, the tadpoles undergo a series of three gradual changes, during which their tails lengthen, and their bodies grow larger. Simultaneously , the formation of legs commences, preparing the tadpoles for a future existence on land.

The tadpoles then progress into baby frogs, characterized by broader mouths, shorter tails, and more developed legs, all while still inhabiting the water. As time passes, these frogs mature until they are ready to leave the water and venture onto land. As they do so, their tails gradually disappear, and they begin to breathe air. In this manner, the life cycle of these frogs is completed. Eventually, the adult frogs seek out mates to lay eggs, and the life cycle begins anew, giving rise to another generation of frogs.

Following are the vocabulary words found in the Sample Answer 1:

Demonstrates (verb)

Meaning: shows clearly by one’s actions
Example : She demonstrated her skills by playing a complex piece of music on the piano.

Evolves (verb)

Meaning: develops gradually
Example : The way we work has evolved over the years, with more and more people working remotely.

Overall (adjective)

Meaning: considering all aspects or factors
Example : The overall impact of the changes was positive.

Initiating (verb)

Meaning: starting something
Example : The government is initiating a new program to help young people find jobs.

Culminating (verb)

Meaning: r eaching a peak or climax
Example : The conference culminated in a gala dinner.

Represent (verb)

Meaning :to stand for or symbolize something
Example : The red, white, and blue colors represent the American flag.

Simultaneously (adverb)

Meaning: at the same time
Example : The two events happened simultaneously.

Subsequently (adverb)

Meaning: happening after something else
Example : The company made a loss in the first quarter, but subsequently, it made a profit.

Gradually (adverb)

Meaning: happening or changing slowly over a period of time
Example : The temperature gradually increased throughout the day.

Steadily (adverb)

Meaning : in a regular and consistent way
Example : The company’s sales have been steadily increasing over the past few years.

Eventually (adverb)

Meaning: after a long time
Example : The team eventually won the game.

Evident (adjective):

Meaning: Clearly seen or understood; obvious.
Example : It was evident that she had put a lot of effort into her presentation.

Embryo (noun):

Meaning : An early stage of development before birth or hatching.
Example : The embryo of the idea soon grew into a fully-fledged project.

Mature (verb/adjective):

Meaning (verb): To develop and reach a fully-grown or ripe state.
Example : It takes several years for a fruit tree to mature and produce good fruit.

Venture (verb):

Meaning : To dare to do something or go somewhere that may be dangerous or unpleasant.
Example : They decided to venture into the dense forest to explore its mysteries.

Formation (noun):

Meaning: The process of being formed or created.
Example : The geologist studied the rock formations in the area to understand their origins.

To conclude, when approaching an IELTS Writing Task 1 process diagram essay, follow these key tips such as analyzing the diagram thoroughly, structuring your essay logically, with an introduction, body paragraphs, and a conclusion, using precise vocabulary and action verbs, maintaining a neutral tone and stick to the facts, including relevant data from the diagram, and concluding by summarizing the main points.

Want to practice more Writing task 1 questions?

Check Out Our IELTS Writing Task 1 Academic Book!

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The Remarkable Metamorphosis of Frogs in Biology

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The Beginning: Frog's Life Cycle Commences with Eggs

Tadpole Transformation: From Embryo to Aquatic Explorer

Completing the cycle: tadpole to frog metamorphosis, life's continuity: adult frogs and the cycle anew.

The Remarkable Metamorphosis of Frogs in Biology. (2016, Sep 09). Retrieved from https://studymoose.com/the-frog-life-cycle-process-essay

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IELTS Writing Task 1: Life Cycle of a Frog – Life Cycle of a Frog IELTS Writing Task 1

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IELTS Writing Task 1: Life Cycle of a Frog – Learn about the process of a Frog’s life cycle and how to write an IELTS task 1 essay about it.

(English below)

IELTS Writing Task 1: Life Cycle of a Frog

Question: the diagram below shows the life cycle of a frog. summarize the information by selecting and reporting the main features, and make comparisons where relevant..

Introduction: The given diagram illustrates the life cycle of a frog, from the egg stage to the adult frog stage.

Overview: Overall, the life cycle of a frog involves three main stages: the egg stage, the tadpole stage, and the adult frog stage.

Details: The life cycle of a frog begins with the laying of eggs in water. The eggs are usually laid in clusters, which are called frogspawn. After a few days, the eggs hatch, and the tadpoles emerge from the eggs.

During the tadpole stage, the tadpoles are fully aquatic and breathe through gills. They feed on algae and other small aquatic organisms. As they grow, they undergo metamorphosis, during which they develop hind legs and lose their tails. At this stage, they are called froglets.

Finally, the froglets develop into adult frogs, which are fully terrestrial and breathe through lungs. They are able to live on land and in water, and they feed on insects, spiders, and other small animals.

Conclusion: In conclusion, the life cycle of a frog is a fascinating process that involves several stages of development. From the egg stage to the adult frog stage, the frog undergoes many changes, both in terms of physical appearance and behavior.

Sample Answer IELTS Writing Task 1:

The diagram illustrates the life cycle of a frog, from the egg stage to the adult frog stage. The life cycle can be divided into three main stages: the egg stage, the tadpole stage, and the adult frog stage.

The first stage of the life cycle is the egg stage, during which the female frog lays eggs in water. The eggs are laid in clusters, which are called frogspawn. After a few days, the eggs hatch, and the tadpoles emerge from the eggs.

The second stage of the life cycle is the tadpole stage, during which the tadpoles are fully aquatic and breathe through gills. They feed on algae and other small aquatic organisms. As they grow, they undergo metamorphosis, during which they develop hind legs and lose their tails. At this stage, they are called froglets.

The final stage of the life cycle is the adult frog stage. The froglets develop into adult frogs, which are fully terrestrial and breathe through lungs. They are able to live on land and in water, and they feed on insects, spiders, and other small animals.

Overall, the life cycle of a frog involves three main stages, and each stage is characterized by significant changes in the physical appearance and behavior of the frog. From the egg stage to the adult frog stage, the frog undergoes a fascinating process of development and transformation.

Một vòng đời ếch ếch bao gồm ba giai đoạn chính: trứng, nòng nọc và người lớn.

Một con ếch bắt đầu cuộc sống của nó như một quả trứng, nở vào một nòng nọc. Con nòng nọc sau đó phát triển thành một con ếch trưởng thành.

Một vòng đời ếch ếch có thể mất từ hai tuần đến tám năm, tùy thuộc vào loài.

Ếch được tìm thấy ở mọi châu lục ngoại trừ Nam Cực. Họ sống trong một loạt các môi trường sống, bao gồm ao, suối, hồ, đầm lầy và rừng.

Ếch là lưỡng cư, có nghĩa là chúng có thể sống cả trên đất liền và trong nước. Hầu hết các ếch dành phần lớn thời gian của chúng ở nước, nơi chúng ít bị ăn thịt hơn.

Ếch là một phần quan trọng của hệ sinh thái. Họ ăn côn trùng, giúp kiểm soát quần thể côn trùng. Ếch cũng là thức ăn cho các động vật khác, chẳng hạn như rắn, chim và động vật có vú.

Ếch có nguy cơ bị tuyệt chủng do nhiều mối đe dọa khác nhau, bao gồm mất môi trường sống, ô nhiễm và biến đổi khí hậu.

Tags: Writing, IELTS

Life Cycle of a Frog IELTS Writing Task 1

A frog’s life cycle consists of three main stages: egg, tadpole and adult.

A frog begins its life as an egg, which hatches into a tadpole. The tadpole then grows into an adult frog.

A frog’s life cycle can take anywhere from two weeks to eight years, depending on the species.

Frogs are found on every continent except Antarctica. They live in a variety of habitats, including ponds, streams, lakes, marshes, and forests.

Frogs are amphibians, meaning they can live both on land and in water. Most frogs spend the majority of their time in water, where they are less likely to be eaten by predators.

Frogs are an important part of the ecosystem. They eat insects, which helps to control the insect population. Frogs are also food for other animals, such as snakes, birds, and mammals.

Frogs are in danger of becoming extinct due to a variety of threats, including habitat loss, pollution, and climate change.

The Frog Life Cycle

The frog life cycle involves dramatic transformations – a process known as metamorphosis. Learn about the intricate stages of frog metamorphosis from the egg to tadpole into the adult frog. Also explore variations in the life cycle among different frog species.

Stages of Frog Metamorphosis

The frog life cycle has three basic steps: eggs → tadpole → adult. However, a lot goes on during each step.

Stage 1: Eggs

The life cycle of a frog begins with eggs, often laid in a cluster or string format, usually in still water or damp places. Females deposit hundreds or thousands of eggs to increase the chances of survival. The eggs are vulnerable to various predators and environmental conditions. Females of some species retain fertilized eggs and release them just before hatching (ovoviviparous) or after they hatch within her body (live-bearing or viviparous).

Stage 2: Embryo

The frog embryo begins forming within a protective jelly-like substance. After a few days, it resembles a tiny fish. The frog’s heart starts beating.

Stage 3: Tadpole

Soon, the embryos hatch as tadpoles. Tadpoles are the larval stage of frog development. These creatures somewhat resemble fish, with gills for breathing underwater and tails for swimming. They eat algae, leaves, and detritus in the water to fuel their growth. But, the tail also serves as a nutrient supply.

Stage 4: Metamorph Stage

After a few weeks, tadpoles undergo remarkable physical transformations in a process called metamorphosis. The tadpole grows hind legs, followed by front legs, while its tail slowly shortens and disappears. It develops lungs to replace gills and its diet shifts from being an herbivore to an omnivore or carnivore , depending on the species. The final transition from tadpole into froglet or frog is very fast (about a day) and the frog is vulnerable to predators and other threats.

Stage 5: Froglet

Once the tadpole grows legs, it is called a froglet. While it still may have a bit of tail left, it leaves the water and explores the terrestrial environment.

Stage 6: Adult Frog

Eventually, the froglet transforms into a mature frog. The frog’s development doesn’t stop here, though. Juveniles continue growing and developing features such as skin coloration, vocal sacs in males, and the ability to reproduce.

Frog Breeding Behavior

Frog breeding behaviors are diverse and fascinating. They usually return to the same bodies of water year after year for breeding purposes. The males attract females with distinctive calls, which also serve to ward off rival males.

Once a male and female pair up, the male clasps the female in a position known as amplexus. As the female releases her eggs, the male fertilizes them externally in the water. In a few species, the female retains her eggs and internal fertilization occurs. The breeding season varies depending on the species and the geographical location.

Variations in Metamorphosis across Frog Species

While the stages outlined above are the norm for most frog species, there are some variations. For example, the members of the family Leptodactylidae (the “marsupial frog”) carry their eggs in a pouch on their back. The eggs hatch into froglets, bypassing the tadpole stage entirely.

In the case of the Surinam toad, eggs embed in the female’s back and develop into froglets. Poison dart frogs lay their eggs on land, and the males carry the hatched tadpoles to nearby water bodies.

Direct development occurs in some species. This is where frogs hatch directly from eggs as small adults (no tadpole stage). The terrestrial-breeding Eleutherodactylus coqui or coqui frog reproduces via direct development. This is an adaptation to a terrestrial lifestyle, where water bodies may be scarce.

Ten Fascinating Frog Life Cycle Facts

Frogs lay a vast number of eggs because the survival rate is remarkably low; only about five out of 1,000 eggs become adult frogs. But, some females lay only part of their eggs at one time, in case conditions become more favorable later.
Tadpoles don’t immediately look like adult frogs. They lack arms or legs but have a tail and they breathe through gills instead of lungs.
The transformation process from tadpole to frog usually takes between 6 to 12 weeks, but in some species, it can last up to 2 years.
Some frogs, like the glass frog, lay their eggs on the underside of leaves to protect them from predators.
The wood frog ( Rana sylvatica ) has a symbiotic relationship with green algae. It includes the algae in the jelly mass with the eggs so photosynthesis helps boost oxygen for the larvae.
The African Bullfrog lays up to 4,000 eggs at a time.
A frog’s lifecycle is an indicator of an ecosystem’s health. They are bio-indicators, meaning their health directly relates to the overall health of the ecosystem.
In cold climates, some species of frogs hibernate in winter. They bury themselves in the mud and their bodies produce a natural anti-freeze that protects their vital organs from damage.
The gastric-brooding or platypus frogs from Australia swallow their eggs and brood them in their stomachs. The babies give birth through their mouth. Both species of these frogs are extinct, but scientists are using cloning to try to bring them back.
Frogs use one of two methods of breeding: prolonged breeding or explosive breeding. In prolonged breeding, adults meet up at a pond or other location at a certain time of year. This is the usual method. In explosive breeding, the whole process of attracting mates, breeding, laying eggs, and progression to adulthood happens very quickly. Explosive breeding occurs where conditions are only favorable for a brief window of time.
McDonald, K.R. (1990). “Rheobatrachus Liem and Taudactylus Straughan & Lee (Anura: Leptodactylidae) in Eungella National Park, Queensland: distribution and decline”. Transactions of the Royal Society of South Australia . 114 (4): 187–194.

Life Cycle of Frogs - Stages of Frog Metamorphosis

There are over 4,800 known frog species found worldwide in a variety of habitats, from rainforests to deserts. They come in a wide range of colors, sizes, and even have unique adaptations depending on their environment. Frogs undergo a remarkable metamorphosis during their life cycle. They start as eggs laid in water, which hatch into tadpoles. Tadpoles are aquatic creatures with gills and tails. Through metamorphosis, tadpoles develop lungs and legs, transforming into adult frogs that can live both on land and in water.

This AnimalWised article will take you through the amazing life cycle of frogs , explaining each fascinating stage.

What is the process of reproduction in a frog?

How are frogs born, stage 1: egg, stage 2: tadpole, stage 3 - transformation from tadpole to frog, stage 4- adulthood.

Frogs ( anurans ) are dioecious , meaning they have separate sexes: male and female. Additionally, many frog species exhibit sexual dimorphism , where males and females have distinct physical characteristics.

Breeding season for frogs typically occurs in spring . During this time, females with mature eggs migrate to bodies of water. Here, they encounter males who use vocalizations to attract mates.

Fertilization in frogs is external, a process known as amplexus . The male clasps the female in a position called amplexus, which can be either inguinal (around the lower body) or axillary (around the chest). This position stimulates the female to release eggs. Simultaneously, the male releases sperm-laden seminal fluid, fertilizing the eggs externally as they emerge.

Frog eggs are typically surrounded by a gelatinous capsule . This capsule absorbs water, causing the eggs to swell and providing some protection from the environment.

The gelatinous mass serves several purposes . First, the lack of a hard shell on frog eggs makes them susceptible to drying out. Laying them in large masses helps retain moisture. Additionally, the gelatinous material offers some physical protection against bumps and potential predators. It can also act as a barrier against harmful microorganisms.

The specific location where eggs are laid varies depending on the frog species. Some species lay their eggs in large masses attached to aquatic vegetation, while others might deposit them within the rosettes of specific plants.

Life Cycle of Frogs - Stages of Frog Metamorphosis - What is the process of reproduction in a frog?

Frogs undergo a fascinating metamorphosis, not a traditional birth .

Within a few weeks of the fertilization, the eggs hatch into young larvae, called tadpoles . These exclusively aquatic creatures have gills for breathing underwater and a tail for swimming. They initially feed on the yolk sac attached to their bodies before developing a mouth and feeding on algae and plants.

Over a period of weeks or months, tadpoles undergo a remarkable transformation . They develop lungs, lose their gills and tail, and grow legs. This process is called metamorphosis.

Finally, the tadpole's body transforms completely , and a tiny frog emerges. When they reach this point, they are ready to live a semi-terrestrial life (hence the name amphibian) although they always need humid places or close to water sources.

While most frog species follow an R strategy , meaning they have many offspring with minimal parental care, some exhibit a K strategy with interesting parental behaviors. Species like the Surinam toad ( Pipa pipa ), Darwin's frog ( Rhinoderma darwinii ), and poison dart frogs ( Oophaga genus ) showcase this.

In these K-strategist species, the male takes a more active role . He protects the eggs laid on the forest floor from predators and even carries water in his cloaca to keep them moist.

Once hatched, the female of these K-strategist species might carry the tadpoles on her back until she places them in suitable locations like bromeliads (rosette-shaped plants). She might even feed them unfertilized eggs until they're strong enough for metamorphosis.

In the upcoming sections, we will explore the distinct stages of metamorphosis experienced by frogs in greater detail. We have organized these stages in the following way:

Stage 1 : Egg
Stage 2 : Tadpole
Stage 3 : Transformation from tadpole to frog
Stage 4 : Adulthood

Intrigued by frog reproduction ? Dive deeper in this article.

A frog's amazing transformation starts within the fertilized egg .

Early on, rapid cell division creates a ball of cells called a blastula . This blastula then undergoes a process called gastrulation. During gastrulation, the cells within the blastula rearrange to form different layers, establishing the basic blueprint for the tadpole's body. This includes the foundation for the digestive system, where the tadpole will eventually process its food.

Next comes neurulation , where a special area called the neural plate thickens. As development progresses, the neural plate transforms into the tadpole's nervous system, which will eventually control its movements and senses – a crucial system for both the tadpole and the adult frog.

Finally, after a period of around 6 to 9 days, depending on the species and water temperature, tiny tadpoles with gills and tails hatch from the eggs , ready to take on their aquatic life.

Ever wondered if frogs have bones ? Read on this other article to find out.

Life Cycle of Frogs - Stages of Frog Metamorphosis - Stage 1: Egg

The tadpole stage is the second crucial phase in a frog's life cycle. This entirely aquatic stage is characterized by several key adaptations that allow the tadpole to thrive in the water until it's ready for its dramatic transformation into a land-dwelling frog.

Following fertilization, a tiny tadpole emerges from the egg. Unlike a future adult frog, the tadpole has a well-defined head and body, but crucially, it lacks limbs for locomotion at this point.

The tadpole's body is specifically designed for life in the water . A strong, flattened tail acts as a powerful swimming propeller, propelling the tadpole through the water. The ventral positioning of the mouth allows the tadpole to graze on algae and other food sources growing on underwater surfaces like rocks and plants. Behind the mouth, a unique feature called an adhesive disc can be found in some tadpole species. This specialized disc acts like a suction cup, allowing the tadpole to cling to plants or rocks in flowing water. This helps the tadpole maintain its position and avoid being swept away by currents.

On either side of the tadpole's head lie feathery structures called gills . These gills are essential for the tadpole's survival, as they allow it to extract dissolved oxygen from the water, similar to how fish breathe. Unlike adult frogs, tadpoles cannot breathe air yet.

While primarily herbivores feeding on algae and other plant matter, tadpoles exhibit surprising dietary flexibility . Rows of tiny teeth (labial teeth) around their mouths are perfect for scraping vegetation. However, some species are opportunistic feeders. Depending on the availability of food sources, they might consume small invertebrates or even resort to cannibalism if food is scarce.

The tadpole stage is a period of significant growth and development. Here, the tadpole focuses on gathering the nutrients it needs to prepare for the next critical stage – metamorphosis . This remarkable transformation will see the tadpole undergo a complete change, transitioning from an aquatic creature to a land-dwelling frog.

Curious about what tadpoles munch on ? Dive deeper in this article.

Life Cycle of Frogs - Stages of Frog Metamorphosis - Stage 2: Tadpole

Stage 3 encompasses the entire metamorphosis process itself . It's the dramatic transformation where the tadpole, a fully aquatic creature, changes into a frog - an air-breathing amphibian capable of living both on land and in water (depending on the species). Here is what happens in more detail:

Hind legs appear first, followed by the forelimbs, gradually transforming the tadpole into a more frog-like shape. These limbs become essential for hopping and maneuvering on land.
Skin pigmentation develops, transitioning the tadpole from its translucent, aquatic appearance to a more camouflaged or brightly colored form suited for its terrestrial life.
Through a controlled cell death process called apoptosis, the tail is reabsorbed . This not only streamlines the body for land movement but also provides essential nutrients for the developing frog's organs and tissues.
Lungs develop within the tadpole's body, while the gills are gradually reabsorbed. This shift allows the frog to breathe air efficiently once it emerges from the water.
The circulatory and nervous systems undergo significant changes to support the demands of an adult frog. The circulatory system becomes more complex to deliver oxygenated blood throughout the body, while the nervous system refines sensory processing and motor control for life on land.
Eyes develop eyelids for protection from dust and debris, and the auditory system refines to pick up sounds better suited for a terrestrial environment. This allows the frog to locate prey, evade predators, and communicate with other frogs.
The tadpole's mouth transforms into a muscular tool perfect for catching prey on land. The tongue becomes protrusible, allowing the frog to rapidly extend it and capture insects and other small invertebrates.

The duration of metamorphosis can vary depending on the frog species and environmental factors . It can take anywhere from a few weeks to several years for a tadpole to become a fully formed adult frog.

Life Cycle of Frogs - Stages of Frog Metamorphosis - Stage 3 - Transformation from tadpole to frog

Following metamorphosis, the young frog (often called a froglet) will continue to grow and develop .

This period is marked by increasing size, further refinement of adult features, and eventually, reaching sexual maturity . The timeframe for reaching sexual maturity varies depending on the species, but it can take anywhere from a few months to several years. Once mature, the frog can participate in breeding and begin the cycle anew by laying eggs.

As an adult frog, the animal will spend its days hunting for food, avoiding predators, finding mates, and potentially caring for offspring (depending on the species). This stage can last for several years, with some frog species living for over a decade in the wild.

Dive deeper into the fascinating world of frogs. This article explores their amazing anatomy .

If you want to read similar articles to Life Cycle of Frogs - Stages of Frog Metamorphosis , we recommend you visit our Facts about the animal kingdom category.

Hickman, C.P., Ober, W.C., & Garrison, C.W. (2006). Comprehensive Principles of Zoology , 13th Edition. McGraw-Hill-Interamericana, Madrid. 1022 pp.
Kardong, K. V. (2007). Vertebrates: Comparative Anatomy, Function and Evolution . McGraw Hill, Interamericana. 782 pp.
Wake, D.B., & Koo, M.S. (2018). Amphibians . Current Biology, 28(21), 1237-1241.

Starfish Life Cycle - Reproduction and Life Stages

The Life Cycle of a Frog

It includes three stages: Egg, larva, and adult

Habitat Profiles
Marine Life
M.S., Applied Ecology, Indiana University Bloomington
B.S., Biology and Chemistry, University of Illinois at Urbana-Champaign

The life cycle of a frog consists of three stages: egg, larva, and adult. As the frog grows, it moves through these stages in a process known as metamorphosis. Frogs are not the only animals that undergo metamorphosis; most other amphibians also experience remarkable changes throughout their life cycles, as do many species of invertebrates . During metamorphosis, two hormones—prolactin and thyroxine—control the transformation from egg to larva to adult.

Riza Arif Pratama / EyeEm / Getty Images

The breeding season for frogs usually occurs during the spring in temperate climates and during the rainy season in tropical climates. When male frogs are ready to breed, they often use loud croaking calls to attract partners. Males produce these calls by filling a vocal sac with air and moving the air back and forth to create a chirp-like sound.

When mating, the male frog holds onto the female's back, clasping his front legs around her waist or neck. This embrace is referred to as amplexus; its purpose is to ensure that the male is in the optimal position to fertilize the female's eggs as she lays them.

Stage 1: Egg

Peter Garner / EyeEm / Getty Images

Many species lay their eggs in calm water among vegetation, where the eggs develop relatively safely. The female frog lays numerous eggs in masses that tend to clump together in groupings known as spawn. As she deposits the eggs, the male releases sperm and fertilizes them.

In many species of frogs, the adults do not stick around to provide further care for their eggs. But in a few, parents remain with the eggs to look after them as they develop. As the fertilized eggs mature, the yolk in each egg splits into more and more cells and begins to take the form of a tadpole, the larva of a frog. Within one to three weeks, the egg is ready to hatch, and a tiny tadpole breaks free.

Stage 2: Tadpole (Larva)

Johner Images / Getty Images

Tadpoles have rudimentary gills, a mouth, and a long tail. They barely move for the first week or two after hatching, and during this time, they absorb the remaining yolk left over from the egg, which provides much-needed nourishment. After absorbing the yolk, the tadpole is strong enough to swim.

Most tadpoles feed on algae and other vegetation, so they are considered herbivores. They filter material from the water as they swim or they tear away bits of plant material. As the tadpole continues to grow, it begins to develop hind limbs. Its body elongates and its diet grows more robust, shifting to larger plant matter and insects. Later in development, the tadpole's front limbs grow and its tail shrinks. Skin forms over the tadpole's gills.

Stage 3: Adult

Danny James / Getty Images

At approximately 12 weeks, the tadpole's gills and tail are fully absorbed into the body, meaning the frog has reached the adult stage of its life cycle. It is now ready to venture out onto dry land and, in time, repeat the life cycle.

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The Frog Life Cycle!

See how this amazing animal grows from tadpole to frog….

Ready for the lowdown on these amazing amphibians? Learning hats on, gang, let’s discover the frog life cycle…

The frog life cycle

Frog Lifecycle | Bull frog sitting on a lilypad

Frogs are animal athletes , with strong powerful legs that allow them to leap out of harm’s way. These powerful limbs are the secret to their success – and incredibly, it takes baby frogs weeks and weeks to grow them!

Like beautiful butterflies , frogs and toads undergo an astonishing transformation – which is called ‘ metamorphosis ‘ – as they grow up. From jelly-like eggs laid in water, they grow into wriggling tadpoles , and finally grow legs suitable for land!

But how does this mesmerising metamorphosis work? Let’s have a look at each stage of the frog life cycle in turn, to find out…

Stage 1: Extraordinary eggs

Frog Lifecycle | large clumps of frogspawn

It all starts with adult frogs laying hundreds of tiny eggs , which clump together in groups known as frogspawn . This happens in early spring , when the weather is just starting to get warmer . Spotting frogspawn is often thought of as being a key sign of spring !

You can hunt for frogspawn in shallow, still water – a garden pond, for example! As the eggs are defenceless, they’re usually laid among vegetation and just below the surface of the water , to give them some protection .

Frog Life cycle | frogspawn nestled between reeds

If you’re lucky enough to spot some of these strange eggs, pay attention to their shape . Frogs lay ‘frogspawn’, which looks like a round cluster of eggs, while toads lay ‘toadspawn’, which comes in long ribbons .

DID YOU KNOW? As far as scientists are concerned, there’s no difference between frogs and toads! They have different characteristics , but share the same family tree .

In the frogspawn, the baby frogs start out as tiny black dots surrounded by a jelly-like substance. Over time, they become comma-shaped , as their tails begin to develop – amazing!

Stage 2: Teeny tadpoles!

After spending 1-3 weeks eating the yolk of their egg, the baby frog hatches into the big, wide world.

Now, the baby frogs are known as tadpoles. They have gills , a mouth , and a long tail , which they need for swimming !

DID YOU KNOW? The tadpole stage of the frog life cycle is also known as the larval stage . Tadpoles are frog larvae , in the same way that caterpillars are butterfly larvae!

For the first week or two after hatching, tadpoles won’t move around very much , as they’re still absorbing some nutrition from the yolk of their egg. However, once the yolk is all gone, the tadpoles are big and strong enough to venture out into their watery world!

Unlike adult frogs, tadpoles can’t go on land – so they feed on plant material filtered from the water, and tear off tiny chunks of nearby vegetation .

Frog Life Cycle | Tadpole close up, showing tail, eyes, and mouth

The legless, water-bound tadpoles slowly metamorphose into frogs over the next 14 weeks .

First, they grow back legs , then front legs too! Soon after, their body starts to change shape , and they’re able to start eating insects .

Frog Life cycle | tadpole that has grown all its legs, but still has a tail

Next, the tadpoles’ tails shrink away , and skin grows over their gills , as they develop lungs and eardrums ! These are super important steps, as they prepare the tadpole for life on land .

Once their gills and tails are gone forever, tadpoles undergo one last 24-hour push , where the metamorphosis completes. Once this stage is finished, the baby frogs emerge from the water as tiny adults !

Amazingly, tadpoles are able to control the timing of their transformation. If they’re living in a dangerous environment, like a pond full of hungry fish, they will metamorphose more quickly, to make their escape! On the other hand, if their pond has lots of plants to munch through, and few predators – or if it’s extra cold on land – tadpoles can delay their metamorphosis, and remain in the water for up to a year. Wow!

Stage 3: Fully-grown frog!

Frog Life Cycle | Tiny adult frog sits on leag

And there you have it – the frogs are all grown up, and ready to head out into the big wide world!

As adults, frogs and toads are much less reliant on water. So long as they stick to the shade and don’t dry out , they can live on land – but they often return to ponds and lakes for a splash!

Before too long, the females will look for water to lay her own eggs. Once that’s happened, the life cycle is complete – what a frog-tastic life they lead!

Frog life cycle | a circular diagram of the lifecycle

Thanks to S. Hermann & F. Richter; Jill Wellington; PollyDot; David Clode, and Venita Oberholster for the images used in this article.

Have you ever found frogspawn, or spotted a frog let us know in the comments below, leave a comment.

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CUSTOMIZE YOUR AVATAR

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Rethink Biology Notes

Ace the biology exams with expert notes

The Cycle of Life in Frogs

Table of Contents

Introduction

The cycle of life in frogs is a complex and fascinating process that involves several stages of development. This essay will examine the life cycle of the leopard frog Rana pipiens, from gametogenesis and fertilization to metamorphosis and gametogenesis.

Gametogenesis and Fertilization

Gametogenesis and fertilization are seasonal events that are controlled by environmental factors such as photoperiod and temperature. In spring, the pituitary gland of the mature female frog is informed that it is time for the eggs and sperm to mature. In most species of frogs, fertilization is external. The male frog grabs the female’s back and fertilizes the eggs as the female releases them. Some species lay their eggs in pond vegetation while others float in the center of the pond without support.

Cleavage and Gastrulation

During cleavage, the volume of the frog egg stays the same but is divided into tens of thousands of cells. Gastrulation begins at a point on the embryo surface roughly 180° opposite the point of sperm entry with the formation of a dimple called the blastopore. The blastopore expands to become a ring, with cells migrating through the blastopore to the embryo’s interior becoming the mesoderm and endoderm, and cells remaining outside becoming the ectoderm.

Organogenesis

Organogenesis in the frog begins with the cells of the most dorsal region of the mesoderm condensing to form a rod of cells called the notochord. These notochord cells produce chemical signals that redirect the fate of the ectodermal cells above it, causing them to become the cells of the nervous system. The mesodermal tissue adjacent to the neural tube and notochord becomes segmented into somites, the precursors of the frog’s back muscles, spinal vertebrae, and dermis. The embryo develops a mouth and an anus, elongating into the familiar tadpole structure.

Metamorphosis and Gametogenesis

Metamorphosis is one of the most striking transformations in all of biology, as almost every organ is subject to modification. The tadpole larva transforms into an adult frog that can live on land, with changes in form that are striking and obvious. The hindlimbs and forelimbs differentiate as the tadpole’s paddle tail recedes, and the cartilaginous tadpole skull is replaced by the predominantly bony skull of the young frog. The tadpole’s lengthy intestine is replaced by the shorter intestine of the adult frog, and the gills are replaced by lungs.

The life cycle of the leopard frog Rana pipiens is a complex process that involves several stages of development, including gametogenesis and fertilization, cleavage and gastrulation, organogenesis, and metamorphosis and gametogenesis. The life cycle is intimately involved with environmental factors and the final result is a striking transformation from a tadpole larva to an adult frog that can live on land.

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IELTS Writing Task 1: Life Cycle of Frog

The supplied diagram illustrates the life cycle of a frog, from egg to adulthood. A glimpse of the diagram reveals that the process consists of six distinct stages, beginning with egg-laying and culminating in the mature frog.

Initially, eggs are laid on the leaves of underwater plants, and are clustered together in a jelly-like substance, often known as frogspawn. The eggs then hatch into tadpoles. This stage is marked by the presence of fish-like appearance. As they develop, they begin to grow hind legs, marking the start of their transformation into froglets.

In the subsequent stage, the tadpole develops front legs and starts to absorb its tail, a stage known as froglet. Finally, the froglet completes its metamorphosis into an adult frog. At this stage, the frog is fully adapted to both terrestrial and aquatic environments, characterized by the complete loss of its tail. Following this two opposite-sex frogs come together for mating and the whole cycle gets repeated.

The diagram below shows the water cycle

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The Life Cycle of a Frog: From Tadpole to Froglet

The life cycle of a frog is a captivating and intricate process that showcases the wonders of nature’s ability to transform. From the tiny, gelatinous egg to the hopping, fully-developed froglet, this journey is filled with fascinating stages of growth and metamorphosis. In this comprehensive article, we will delve into the remarkable metamorphosis of a frog, exploring each phase of its life cycle in intricate detail.

Eggs – The Beginning of Life

The life of a frog begins in water, where it lays its eggs in carefully selected locations to ensure the survival of its offspring. These eggs are typically laid in clusters, known as frogspawn, and are attached to aquatic plants or floating debris to provide protection from predators and the elements. Within the protective jelly, the eggs develop over a period of days, depending on environmental factors such as temperature and humidity.

Each clutch of eggs can contain hundreds or even thousands of individual eggs, increasing the chances of some surviving to adulthood. The parent frogs exhibit remarkable parental care by guarding the eggs and tadpoles from potential threats, ensuring the best possible start to their offspring’s life.

Tadpole – The Aquatic Larva

Once the eggs hatch, they give birth to tadpoles, the aquatic larval stage of the frog’s life cycle. Tadpoles are peculiar in appearance, resembling small fish with elongated, translucent bodies and external gills for breathing underwater. These gills facilitate the exchange of oxygen, enabling the tadpole to survive and grow in its aquatic environment.

During this stage, tadpoles are entirely herbivorous, feeding on algae and plant matter found in their watery habitats. They propel themselves through the water using their muscular tails and exhibit distinct schooling behaviour, forming groups for safety and social interaction.

Metamorphosis – The Transformation Begins

As tadpoles grow, they enter a crucial phase known as metamorphosis. This process is a marvel of natural engineering, where tadpoles undergo a series of dramatic changes to become adult frogs. Metamorphosis is driven by a complex interplay of hormonal changes, triggered by environmental cues like temperature, water quality, and food availability.

The first visible sign of transformation is the development of hind legs, which emerge as small buds behind the tadpole’s tail. Over time, the hind legs elongate and develop into fully formed limbs. Subsequently, the front legs begin to emerge, and the tadpole’s body shape starts to change.

Development of Lungs

With the development of limbs, the tadpole’s transition from an aquatic life to a terrestrial one begins. Lungs start to form as internal gills begin to degenerate. This adaptation prepares the tadpole for a life outside water, where it will soon breathe atmospheric air.

As the tadpole starts to explore its surroundings beyond the water, it must strike a delicate balance between respiration through gills and the gradual use of newly developed lungs. During this time, the tadpole may exhibit a mix of breathing methods, allowing it to adapt to different oxygen-rich environments.

Absorption of Tail

As the tadpole continues to grow and adjust to its changing body, its tail, once a vital tool for swimming, starts to shrink. The tail’s tissues are gradually absorbed into the body, providing essential nutrients to fuel the metamorphosis process. This tail absorption eventually leads to the disappearance of the tadpole’s tail, symbolising its successful transition to adulthood.

Skin Changes

Throughout the metamorphosis, the tadpole’s skin undergoes significant changes. It becomes thicker and more robust, with special glands developing that secrete mucus to keep the skin moist on land. This adaptation is crucial for the frog to survive in a terrestrial environment, as it helps protect against dehydration and supports the frog’s ability to breathe through its skin.

The skin of the frog also plays a vital role in thermoregulation, allowing it to regulate its body temperature effectively. The colour and texture of the skin can change to match the environment, providing camouflage and protection from predators.

Vision and Hearing Adaptations

As the transformation progresses, the frog’s eyes and ears undergo changes to accommodate its new life on land. Its vision improves, adapting to the changing light conditions outside the water, while its hearing also becomes more sensitive to sounds in its surroundings.

Frogs have large, protruding eyes that allow for excellent binocular vision, enabling them to accurately judge distances and accurately target prey. Their eyes are also adapted to see in low light conditions, making them effective hunters during dusk and nighttime.

The development of the frog’s ears is equally fascinating. Unlike humans, frogs lack external ears, but they possess an eardrum or tympanum on each side of their head, just behind the eyes. These eardrums are covered and protected by a thin layer of skin. Through the vibrations sensed by their eardrums, frogs can detect a wide range of sounds and communicate with other frogs for mating purposes.

Diet Transition

With the completion of metamorphosis, the young froglet now resembles a miniature version of an adult frog. It’s time for another significant change: the transition in diet. Froglets’ diet consists of insects, small invertebrates, and sometimes even other smaller frogs. They use their long, sticky tongues to catch prey with precision.

Froglets are skilled hunters, using their impressive vision and accurate tongue projection to capture fast-moving insects with exceptional speed and accuracy. The transition to a carnivorous diet is essential for the frog’s growth and development into a healthy adult.

Habitat Transition

The mature froglet leaves the water to explore the surrounding terrestrial environment. They find shelter in damp areas, such as marshes, ponds, or forests, where they can stay close to water sources but also find insects and other food.

During this phase, the froglet faces new challenges in adapting to terrestrial life. It must navigate potential predators, find suitable food sources, and establish territories to attract potential mates.

Adult Frog – The Final Stage

As the froglet continues to grow, it eventually reaches adulthood. At this stage, the frog has fully adapted to its life on land. The adult frog is equipped with strong limbs for hopping, excellent vision for spotting prey, and a unique vocal sac that enables it to produce a wide range of sounds for communication and mating.

Adult frogs come in various shapes and sizes, depending on their species. Some have smooth, shiny skin, while others may have rough or warty textures to aid in camouflage. They are exceptional jumpers, capable of leaping significant distances to escape predators or catch prey.

The vocal sac, present in many male frogs, is an inflatable pouch situated beneath the throat. By filling and deflating this sac, frogs can produce a diverse array of calls, used primarily for attracting mates during the breeding season. Each frog species has a unique call, allowing females to identify suitable mates amidst the chorus of competing calls.

The life cycle of a frog, from tadpole to froglet, is a remarkable testament to nature’s adaptability and resilience. The journey from a small, aquatic larva to a fully developed adult frog showcases the wonders of metamorphosis and the intricacies of the natural world. As these amphibians undergo various physical and behavioural changes, they find their place in both aquatic and terrestrial ecosystems, playing crucial roles in maintaining the delicate balance of nature.

Observing and understanding this incredible life cycle reminds us of the beauty and complexity of the natural world around us. It serves as a poignant reminder of the importance of preserving and protecting these habitats, ensuring the continued existence of these fascinating creatures for generations to come. The life cycle of a frog is not only a captivating story of transformation but also a testament to the marvels of evolution and the interconnectedness of all living beings on Earth.

Sam loves to learn about animals and their habitats. He has been a nature lover from a very young age, and has been writing papers and articles about wildlife for as long as he can remember.