Why Do Animals Stop Growing? The Real Truth About The Growth Of Animals!

If you love animals, then you have searched about animals all the time, and you have already seen different kinds of animals, large or small. 

You notice one thing right? You notice that different animals have different sizes. After noticing that, you come to think, do animals stop growing? Will small fishes will be small throughout their lives? Another question you ask yourself is:

Why do animals stop growing? 
Animals stop growing because they are genetically programmed to do so. Animals have different genes and hormones that determine how large they will grow. Also, the longer animals live, the more they come into contact with predators, diseases, and natural disasters that may cause ending their life earlier before they get big.

However, some animals don’t stop growing, and we are going to tackle that as well. Also, you have many things to learn about this topic, so let’s move on!

Why Do Animals Stop Growing?

Why Do Animals Stop Growing?

Animals have different genes and DNA, that decide how large they will get. Fishes are naturally small, elephants are naturally large, and planktons are incredibly small. 

The DNA of the fish is different from the DNA of the elephant. They will both become an adult, but their sizes will vary on their genes and DNA. It looks unfair, but this is how our creator made them. Even though animals have different sizes, they all have a purpose on our planet. 

Not because fishes are small, they don’t have a purpose, or because insects are small, they don’t have a purpose. All of us have a purpose, large or small. 

Another reason why animals stop growing is that the more they live the more they will encounter danger throughout their lives. They might encounter predators, natural disasters, or diseases that can kill them earlier before they reach their maximum growth.

Animals are mobile. If they grow too big, it would lead to an exponential increase in energy requirements, and mobility will be hindered. 

Also, scientists have said that the growth of animals also depends on what they eat or their diet. That is why you will notice that animals that eat plants are usually taller than carnivore animals. Carnivore animals are more muscular and have robust bodies than plant-eating animals.

Do Animals Have Unlimited Growth?

Why Do Animals Stop Growing?

The actual size of animals is mostly set from birth. The growth of animals is also influenced by their environment. Animals will stop growing once they reach adulthood. However, there are animals like kangaroos who never stop growing. 

So do animals have unlimited growth? Yes because some animals have unlimited growth. Kangaroos will continue to grow, slowly, until they die. Corals as well have the capacity to grow unlimited, and they never stop growing. This pattern is called indeterminate growth.

Most fish, amphibians, and invertebrates are indeterminate growers. They can get bigger and bigger! Indeterminate growers can get big as their environment and diet allows. 

But, why can’t we see large snakes, fishes, and other indeterminate growers? Because the bigger an animal gets, the more they will contact predators, diseases, and natural disasters that will cause them to die earlier before they grow into a large size.

What Are The Animals That Never Stop Growing?

Why Do Animals Stop Growing?

Even though most animals have limited growth because of their genetics, there are still some animals that never stop growing. Let’s check them out! 


Lizards are one of the animals that never stop growing. The lifespan of lizards is usually longer than other mammals. However, lizards are finite. They don’t have unlimited lifespans. 

Lizards don’t stop growing, and they grow very quickly until they reach maturity. They don’t stop growing until they reach maturity, and they continue to grow slowly for the rest of their life. 

Lizards are not immortals. They will stop growing when they die of old age. However, some lizards die earlier, especially lizards living in the wild, because they are prone to predators and other dangers.


Have you ever watched a movie named Anaconda? If yes, then you probably know why the snake is on our list. Even though some people might think that a snake cannot grow that large, it was proven that snakes can grow very long as an elephant. 

Snakes never stop growing, and they can grow very long! It depends on what they eat and on their diet. Some people said that snakes that eat large animals like cows will most likely grow larger. 

Snakes never stop growing. When they grow, they will just shed their skins. If their current skin doesn’t fit anymore or is worn out, snakes will change their outer layer of skin. Shedding is part of a snake’s growing process. 

Snakes will continue to grow until they die. The only reason why we can’t see a snake that has elephant-like size is that they die early. After all, they are prone to dangers and predators.


Amphibians, like frogs, are also indeterminate growers. Some frogs cease growing when they die. The only reason why we don’t see an amphibian that has the size of an elephant is that they die early. After all, they are exposed in the wild, and their lifespans are too short. 

If amphibians have a lifespan like sharks, then they will most likely grow big like elephants. Frogs are programmed already to die earlier because if they don’t we’ll see large frogs jumping around our cities or villages. 


Corals are the slowest growing animals. They grow between 5 to 25 millimeters per year. However, branching and staghorn corals are fast growers. They grow 20 centimeters per year. Corals grow much better in warm water. They prefer warm, clear, and shallow water. 

Corals are also indeterminate growers. They continue to grow, but slowly until they die. Corals also have long lifespans. Red corals, for example, can live five hundred years old! That is why corals are inevitably large because they have long lifespans, and they never stop growing.


Sharks keep growing until they die. A shark’s lifespan can reach up to 50 years old. Sharks that are not prone to danger or that have not been killed by humans or other animals will most likely grow like the size of the whales. 

Great sharks, for example, need decades for them to reach the adult size. Once they reach their adult size, they will continue to grow slowly throughout their lifetimes. After sharks reach maturity, their growth only slows, and it doesn’t stop until they die. 


Fishes never stop growing. Some fishes grow fast, and some fishes grow slow. Fishes usually reach their adult sizes in a few months, but they don’t stop growing because after they grow their adult size, they will continue to grow but slowly. 

Can a fish outgrow its tank? Fishes like goldfish can grow larger than their tanks if taken care of. Fishes will continue to grow as long as they are breathing, and they can outgrow their tank. After reaching maturity age, their growth will be slowed down. 

The only reason why we don’t see small fishes that have the size of a shark or whale is that small fishes usually have short lifespans. Also, smaller fishes are most likely to get eaten by either big sharks or humans. 


Turtles also can never stop growing. Even your pet turtles can never stop growing. Turtles will grow very slowly once they reach their mature age. They will grow very slowly for many years, but they won’t stop growing. 

Turtles also have a long lifespan. They can live between 10 and 80 years old, while the larger species can live up to 100 years old. There are some anecdotal records where turtles can live up to 150 years old. 

Turtles continue to grow, but they will grow very slowly that you will not notice until they die. It prevents turtles from aging as mammals and birds do. Turtles have slow metabolisms that are why they can survive long without food or water.


The skeletons of kangaroos continue to grow, slowly, until they die. Kangaroos have robust and powerful bodies that can take down any animals, including lions. They have large bodies and never stop growing. 

The only reason kangaroos will stop growing is if they die. Kangaroos are prone to powerful predators like lions and tigers. 

What Are The Factors That Affect The Growth Of Animals?

Many factors determine the growth of an animal. It includes their genes, diets, or food they eat and their environment. 

Let’s take a deeper look at the factors that affect the growth of animals!


Animals have different genes and DNA, which determine how tall or large they will grow. Elephants have different genes than fishes because elephants can grow larger than fishes. However, elephants will stop growing until they reach maturity age while fishes don’t 

Genes affect the growth of an animal. Their DNA determines how large they will be and if they will stop growing. There are also some genetic disorders that some animals are facing that can have an impact on their growth. 

Animals that have genetic disorders will most likely grow abnormal. Some elephants with gene issues will grow smaller than the usual size. In humans, we call this dwarfism. Animals can also experience dwarfism. 

Genetic disorders in animals can also cause various sickness to them like cancer, patella luxation, common heart diseases, and many more. Genetic disorders can also affect the growth of animals. 

Diet and Food

Yes, of course! Food and diet affect the growth of animals. When you notice, animals that eat plants are much healthier and live longer than omnivore and carnivore animals. Herbivore animals like elephants and giraffes grow taller and powerful than their predators. 

Diet and healthy food are essential for every animal. When animals don’t eat healthy foods or don’t have healthy diets, they will most likely die earlier. 


Yes! The environment also affects the growth of animals. Animals that live in an environment where predators are abundant will most likely die early and won’t grow up to their full size even though they are indeterminate growers. 

Remember, the bigger an animal gets, the more it will be prone to dangers because they will be more likely to have contact with their predators, and have health diseases that will cause them to die early before they reach their large size. 

Animals living in an environment where food and water are scarce will most likely die because of starvation or dehydration. That is why the environment plays an important role in determining the growth of an animal. 

What Animals Grow Very Big?

Below are the top seven animals that grow very big throughout their lives! Let’s check them out! 


Whales are the largest animal in the world! Blue whales are the largest of all whale species. Blue whales weigh 198 tons, and they have a length of 98 ft. 

The tongues of the blue whales can weigh as much as the elephants and their hearts can weigh as a car. However, even though they are big, they don’t like the taste of fishes like sharks do. 


Sharks keep growing throughout their lives. They belong to the largest animals because of their sizes and their ability to grow forever! Sharks will never stop growing, and they will continue to grow slowly. 

The largest shark in the world is the whale shark. That is why the species is named the whale shark because of its huge size like a whale.


Elephants are the largest land-living animal on the planet. African elephants are the biggest among all species of elephants. They can weigh up to 7 tons, and they can grow to 35 ft.

Elephants are large mammals that eat plants and fruits. Even though elephants are strong and large, they are still prone to predators like lions and tigers that are smaller than them.


Giraffes are also big mammals. They have a height of 19 ft, and they are the tallest living animal on Earth. Giraffes can usually be seen in the grasslands of East Africa. They love to eat vegetables, fruits, and plants. 

Giraffes can run as fast as 35 miles an hour even though they are large. They can carry themselves. They can’t reach the ground even though they have long necks.


Bears are the largest living land carnivore. The brown bears and polar bears are the biggest of all bear species. They weigh 907 kg, and they can grow up to 10 ft when standing on their legs. 

Brown bears can be found on the mountains of North America, Europe, and Asia. The polar bears can be found in the arctic circle. 


Ostriches are the largest living bird. They have a height of 9 ft, and they weigh 158 kg. Because they are too big, they can’t fly. 

Even though ostriches can’t fly, they are still inevitably strong because of their sizes. Ostriches have large wings, and they have strong legs to run fast and to kick predators away.

Saltwater Crocodiles

The largest living reptile award goes to saltwater crocodiles. They grow an average length of 17 ft, and some can reach up to 21 ft. Saltwater crocodiles can weigh up to 453 kg. They can be seen in the salt waters of India, Asia, and Australia. 

Saltwater crocodiles have powerful teeth that can kill and crush prey in one glimpse, and they can eat whatever they want. They usually feed on smaller animals than them.

Final Words

Animals, including humans, can only grow into limited sizes, and our genes dictate how big and tall we are going to get. However, some animals never stop growing, and they continue to grow until they die. 

Most animals that don’t stop growing normally don’t reach their large size because they usually die earlier because the bigger they get, the more animals are prone to predators and various illnesses. 

I hope you have learned today! If you want more facts about animals, check out our main menu at the top to check what facts about animals you prefer to know!

Jake Willhoite
Jake runs AnimalDome.com and has had cats and dogs his entire life. As a kid his family adopted several dogs from the local shelter which set him down the path of animal rescue.
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