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Are Crocodiles Cold-Blooded or Warm-Blooded?

Crocodiles are cold-blooded animals. This means that they have to use external sources to regulate their body temperature, such as basking in the sun or submerging themselves in water. As such, crocodiles cannot survive extreme temperatures for long periods.

Nile Crocodile
Crocodiles use the heat of the sun to warm their bodies

As a cold-blooded animal, it does not mean that the crocodile has cold blood upon touch. It only means that the blood’s temperature changes as the temperature outside the body changes. It is why many crocodiles live in warm regions of the earth.

Will Crocodiles Die in the Cold? 

Crocodiles are not well-adapted to living in cold conditions for long periods. Without adequate warmth from their environment, they can not sustain a high enough body temperature to survive.

Although crocodiles are generally unable to survive in cold weather, some crocodiles and alligators can survive for short periods by submerging most of their body in water, leaving only their snout exposed to the air.

This process helps them avoid the cold and maintain their body heat since the water is warmer than the surrounding environment above the ice.

There are more than 20 types of crocodile, and none of them live in freezing conditions.

What are the Differences Between Cold-Blooded and Warm-Blooded Animals? 

Cold-blooded animals and warm-blooded animals have many differences. Some of the most notable are listed below. 

1. Metabolic Rates

Cold-blooded animals depend on the environment on how fast they will digest food and use energy. Warm-blooded animals are not like this. The change in environmental temperature has no impact on how warm-blooded animals metabolize food. 

2. Resting Adaptation

Some cold-blooded animals go through what is called hibernation during extreme cold. For crocodiles and alligators, this phase is called brumation. In the summer, they go through aestivation, a dormancy process during drought or extreme heat. 

3. Heat Regulation

As cold-blooded animals, crocodiles regulate their body temperature by basking under the sun. Warm-blooded animals do not need any extra activity to regulate body temperature. This regulation happens internally for warm-blooded animals like mammals. 

Read More: Are Crocodiles Considered Marine Mammals?

4. Resistance to Microorganisms

For cold-blooded animals, what they do is increase their body temperature to fight microorganisms. They do not do this internally but rather consciously. 

Crocodiles want high heat, so they stay under the sun. For warm-blooded animals, this process happens from the inside, and it is a product of evolution—it is why humans have a fever when sick.

5. Survival 

Cold-blooded animals will die in extreme climate conditions. Since their bodies cannot regulate their temperature, prolonged exposure to extreme climate will cause a serious imbalance and then death. 

Warm-blooded animals can adapt to extreme conditions but with extreme caution. It is why mammals can survive winters and also survive hot deserts. 

crocodile
Crocodiles can’t sweat, so they use shade and water to keep cool

What is the Preferred Body Temperature of Crocodiles?

The ideal body temperature for most crocodiles is around 30°C (86°F), although it varies by species.

Most of the time, crocodiles’ bodies face the sun to guarantee that they get as much heat as possible. Once they get warm enough, they shift positions. This time, they face the sun to reduce the heat intake. 

Like dogs, crocodiles use their mouths to regulate body temperature. Crocs open their mouths to cool down if it gets too hot. This process is what experts call evaporative cooling

Are All Reptiles Cold-Blooded?

Almost all reptiles are cold-blooded, but there is a species of lizard called the tegu (Salvator merianae) that some scientists consider to be warm-blooded. When the mating season is close, the tegu’s body begins to warm up. The tegu is the world’s only known warm-blooded lizard

Tegu (Salvator merianae)
Tegu (Salvator merianae)

Have Crocodiles Always Been Cold-Blooded? 

Although modern crocodiles are cold-blooded, some recent studies show that some prehistoric crocodile ancestors were warm-blooded. 

Scientists studied the oxygen isotope of fossilized teeth that came from prehistoric crocodiles. The study found out that at least one extinct crocodile, one that belonged to the metriorhynchid family, was a warm-blooded animal.

What are the Evolutionary Benefits of Being Cold-Blooded?

At the outset, it seems that warm-bloodedness is crucial to survival. It is not so, as there are some benefits to being cold-blooded. Evolution is what made crocodiles this way, and below are some of the benefits. 

1. Eating Less Food

As cold-blooded animals, crocodiles do not need to eat a lot of food. There is no need for it since their bodies do not regulate their body temperatures. What it means is that they do not need a lot of energy for metabolism. 

Warm-blooded animals, on the other hand, have to eat consistently. The food that warm-blooded animals eat burn, and this process is what keep the animals warm.

2. Adaptability to Inhospitable Areas

Cold-blooded animals do not need to eat often. As such, they can live in areas where food is scarce. Warm-blooded animals will not thrive in places where there is food scarcity—they will die of hunger. 

A good example of this is the desert. Although humans can live in deserts, they can only do so because they domesticate animals.

If left alone to only live what the desert has to offer, warm-blooded animals would die. On the other hand, cold-blooded animals like lizards can thrive in these wastelands. 

3. Dealing with Bacterial Infections

Bacteria and other microorganisms spread diseases. In cold-blooded animals, it is difficult for bacteria to survive. Bacteria need an ideal temperature to spread. 

Warm-blooded animals, therefore, are the perfect host for bacteria. If infected, the bacteria have a good environment from which they will multiply. It is the reason warm-blooded animals develop strong immune systems to fight off bacteria and microorganisms. 

Crocodile mouth basking
Crocodiles open their mouths to cool down, similar to a dog panting

Summary: Are Crocodiles Cold-Blooded or Warm-Blooded?

Crocodiles are cold-blooded reptiles. They cannot survive in extreme climate conditions. As cold-blooded animals, they also do not have any internal mechanisms to regulate their body temperature.

All crocodiles look similar, but alligators are usually darker and a bit smaller.

The crocodile’s cousin, the alligator, can survive winter. They leave their snouts above the frozen pond’s surface and keep their bodies underwater. Crocodiles cannot do this—they live exclusively in dry land and temperate regions.

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