Why So Many Eggs?

Learn why there are so many tadpoles in your pond and why frogs lay so many eggs.


Mating

During spring, male and female frogs meet at ponds to mate. During the mating season you can find some ponds full of frogs, like in the picture below!

When they meet, frogs have to communicate with each other. One important way for frogs to do this is through singing. There are many different types of calls frogs can make and some are specifically used in finding a mate. Listen to some croaking calls of frogs below, provided by Darcy Kelly:

Growling
Chirping
Female advertisement call
Male answer call

After singing to each other, frogs can begin to mate. The male frog will position itself on top of the female near its hind legs. Look at the photos below- notice the female is a different colour and much bigger than the male.


Frog Spawn

Once courtship has taken place, the female lays huge numbers of eggs and the male fertilises them as they are laid. A female can lay up to 4000 eggs!

These eggs are called frog spawn and are laid in big clumps. The fragile developing tadpole is surrounded by a protective jelly layer, which also helps the frog spawn float on the surface of the water.

If you look closely at this picture you’ll see that it’s completely full of frog spawn!

Once the eggs are laid and fertilised, both the parents leave the pond and the tadpoles develop without help from their parents. This links to why female frogs lay so many eggs!


So Many Eggs!

Many predators like to eat frog spawn. If everyone wants to eat your babies and you are not there to protect them, it’s a good idea to lay lots of eggs! Laying many eggs means more tadpoles will hatch and it will be more likely that some will survive.

It is thought that only 1 in 50 eggs makes it to become a froglet without being eaten. Those are not very good odds! At each stage in the picture below, many eggs and tadpoles are eaten. So not many surviving froglets leave the pond. Animals that eat tadpoles and frogs are predators. The tadpoles or frogs are therefore called the prey. You can learn more about tadpole predators here and look at amazing photos of tadpole predators here!


Care From Parents

When a mother or father looks after its offspring for some or most of its life, this is called parental care. Some animals provide a lot of care and protection for their offspring. This means feeding them, sheltering them and protecting them from harm or predators. Usually animals with fewer offspring provide more parental care and make more effort in making sure those offspring survive.

  • by AboutKidsHealth

Some organisms do not look after their offspring.

Plants cannot physically look after their seeds which means less of these offspring will survive. To increase the chances of some surviving, they therefore produce lots. This is the same as frogs and other animals producing lots of eggs, so at least some of these offspring will survive.


Quiz Time!

Results

We hope you know more about why female frogs lay so many eggs! Click here to explore more topics.

#1. What time of the year do frogs usually mate?

#2. What physical differences distinguish male frogs from female frogs? Choose all that apply.

#3. Fill in the blank: "A female frog can lay up to _____ eggs!".

#4. What allows frog spawn to float on the surface of the pond?

#5. How many frog eggs are thought to survive and develop into froglets without being eaten?

Finish

Remember to attribute photographs, videos or work where appropriate! This is not needed unless used online, but if you’re unsure please refer to the creative commons licence rules. For media credits of the images above, please refer to the next page.

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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