Tadpoles and Frogs

Learn more about tadpoles and frogs and why they are so important in science!

Frogs are Amphibians!

Frogs are amphibians, which means they can live in both water and on land. Frogs are not the only example of amphibians, look at the pictures below for some more!

Smooth newt – by Magnus Maske
Axolotl – by John Clare

Almost all amphibians lay eggs in or near water. When baby amphibians first hatch, they have gills which help them to breathe underwater. As they grow they develop lungs, which helps them breathe air. These changes are part of an amphibian’s life-cycle. See if you can spot the tadpoles’ gills in the pictures below!

by Lia Gilmour
by Lia Gilmour

Amphibians are also cold blooded which means their bodies match to the temperature of the space around them. When it’s warm outside amphibians stay warm, but when winter comes they hibernate to survive the cold temperature. Slide between the two images below to see how weather can affect frogs and tadpoles.

When the weather is warm, the frogs are out and about and enjoying the warmth! You can even see tadpoles in the pond. But when the weather is cold, the pond is frozen over and you can’t see any tadpoles or frogs. Can you spot where the frog is hibernating?

Let’s recap…

Frogs are amphibians.

They can live in both water and on land.

Amphibians have gills when they’re young to help them breathe underwater. These later develop into lungs.

Amphibians are cold blooded.

Why Do We Study Tadpoles?

The brain is a very complex organ, which makes it hard for scientists to study it in animals like humans! To make this task easier, scientists can look at smaller and simpler animals to study the brain. This is where young tadpoles come in.

Young tadpoles have simpler brains and they show simpler behaviours. Scientists can watch young tadpoles eating or swimming and study how their brains make them complete these tasks.

Tadpoles also grow into adults quite quickly compared to the humans. This helps scientists study the brain from when frog eggs (also called frog spawn) first hatch to when they change into fully grown frogs. Frogs also lay hundreds of eggs, so there are always plenty to study! To learn about why frogs lay so many eggs, click here.

Scientists have to take care of the tadpoles they study so they can grow into adult frogs. But not only scientists can do this, you can too! To learn about how to raise tadpoles at home, click here.

The Digestive System

 

The digestive system is modified to account for the change of the herbivorous diet of the tadpole to the carnivorous diet of the frog.

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The Skin

 

The skin adapts for the change from a purely aquatic lifestyle to an amphibious lifestyle.

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The Reproductive System

 

The urogenital system develops to allow for reproduction in adulthood.

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The Skeleton

 

The skeletal structure develops to accommodate the change from tail swimming to using legs to move around. The skull also needs to be remodelled for a frog's change in vision.

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The Nervous System

 

A tadpole sees from eyes that are positioned on opposite sides of the head. During metamorphosis, the optical nerves develop to accommodate a frog's binocular vision, where the eyes are positioned at the front of the head.

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1. Mating and Laying Spawn

 

Male and female frogs go to ponds in the winter. They mate in the spring, and the female lays big clumps of eggs.

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2. Frog Spawn

 

Frogs eggs are called frogspawn. Each round black egg is about 1 mm wide and is surrounded by a blob of jelly. Other animals produce spawn as well, which you can look at here.

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3. Maturing Frog Spawn

 

After a few days, the eggs begin to grow into tiny tadpoles inside the jelly.

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4. Hatchlings

 

Then the tadpoles hatch! They are about 5 mm long and they can’t swim (yet). They can bend their body from side to side using special muscles along their trunks and tails.

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5. Young Tadpoles

 

When their tail is big enough, they swim off into the pond to start to feed. At first they have gills (the pale protrusions from the head region in the left photo) so they can breath underwater like fish. Young tadpoles feed by grazing the surface of pond weeds and also eating tiny floating plants called algae.

Click here to play a tadpole feeding game called Taddypole!

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6. Maturing Tadpoles

 

Later they develop lungs and can swim up to the surface of the water to breath. The gills are absorbed back into their bodies and eyes develop. Older tadpoles are then able to feed on small animals like young insects.

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7. Mature Tadpoles

The next stage in development is to grow back legs. Tadpoles during this stage need to eat meat in order to get the proper nutrients to grow.

If you are looking after tadpoles, be careful as they can eat each other if you don't give them meat to eat! Click here to learn more about how to look after tadpoles as pets.

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8. Froglet

Finally, tadpoles grow front legs and their tail shrinks until it almost disappears. This is when they climb out of the pond and start living on dry land. Small frogs are commonly called froglets.

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9. Adult Frog

The little froglets will stay by the pond and slowly grow over the summer, eating small insects and worms. They will hibernate just like other adult frogs in damp spots near ponds from autumn until the next spring.

After four years, the new frogs will become adults and will be ready to mate and begin the cycle again.

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Copy - 9. Adult Frog

The little froglets will stay by the pond and slowly grow over the summer, eating small insects and worms. They will hibernate just like other adult frogs in damp spots near ponds from autumn until the next spring.

After four years, the new frogs will become adults and will be ready to mate and begin the cycle again.

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Desert Habitats

Desert habitats are the driest habitats in the world. Most people only think of very hot habitats as being deserts, but cold habitats can be deserts as well! Animals and plants that live in deserts have the ability to survive on very little water and animals can control their body temperatures so they stay at the right level.

 Some examples of plants and animals that live in deserts are cacti, the desert tortoise and the artic fox.

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Coral Reef Habitats

Coral reefs are found in warm tropical oceans all around the world. Coral reefs can be found in both shallow and deep water and take hundreds of thousands of years to grow! They provide food and shelter to many fish and other animals, making them habitats that are home to so many different types of life.

Some examples of plants and animals that live in coral reefs are the sea star, sea grass, the octopus and clown fish.

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