According to evolutionary biologists, amphibians evolved from an ancient fish hundreds of millions of years ago. The millions of years of evolution between the fish and now have led to the diversity currently witnessed in the class of animals.
There are thousands of known amphibian animals on the planet and many more are being discovered every year. So how exactly do amphibians control their body temperature? Are they warm-blooded? Are they cold-blooded?
Before I share with you the answers to these questions, allow me to differentiate the amphibian class from other classes in Kingdom Animalia. The information I share with you below will help you to understand amphibians better. It will also help you to appreciate their mechanism of regulating body temperature.
How Amphibians Differ From Other Classes in Kingdom Animalia
There are many things that distinguish amphibians from other classes of kingdom Animalia such as mammals, reptiles, birds, and insects.
The biggest difference between amphibians and other animals is in the habitat. Mammals and reptiles can live a significant distance away from a constant body of water, while amphibians cannot.
Amphibians prefer living close to constant bodies of water such as rivers, streams, lakes, wetlands, rainforests, and springs. They cannot live in dry habitats such as deserts. This is because their bodies lose a lot of water to the environment through the evaporation of moisture from their moist skins. So they need to live near permanent bodies of water to frequently replace the lost water.
The other major difference between amphibians and other animals is in the life cycle. The majority of common amphibians undergo metamorphosis. This means they go serious transformations in their lifecycle for instance frogs are released as eggs which hatch into tadpoles which grow into adult frogs. While other animals largely stay in the same body shape/ form throughout their life cycle.
Another major difference between amphibians and other animals is in the skin. The majority of amphibians have got smooth and moist skin. In contrast, the majority of reptiles e.g. crocodiles, lizards, and snakes have got hard skin. The hard skin on reptiles protects them from moisture loss, their habitats, and UV rays. Amphibians have no such protection because their skin is smooth and moist and usually thin.
Orders of Amphibians
As I mentioned in the introduction, there are thousands of known amphibians. They all belong to a subclass known as Lissamphibia and are grouped into three orders – Anura, Caudata, and Gynophiona.
Anura – The amphibians that belong to this order are the most popular amphibians namely, frogs and toads. Frogs are known for their smooth, thin, and moist skin, while toads are known for their dry and warty skin. Frogs are also distinguished from toads by their longer hind limbs. Nearly 90 percent of all amphibians belong to this order and they are found everywhere on the planet except in the North Pole and the South Pole.
Caudata – The amphibians that belong to this order include salamanders and newts. They look lizard-like but they are quite unlike lizards. This is because, unlike lizards, they generally have smoother skin and prefer living close to constant water bodies. Salamanders vary in size. They include tiny salamanders that only grow as long as 3 cm and big species that grow as long as 180 cm.
Gymnophiona – The amphibians that belong to this order include caecilians. They look serpent-like because they are long and have no legs. And they are not very well known by many people. Just like amphibians of the order Caudata, they significantly vary in size.
Are Amphibians Warm-Blooded?
No, they are not. Amphibians are not warm-blooded animals. Examples of warm-blooded animals include most mammals and birds.
Are Amphibians Cold-Blooded?
Yes, they are. Amphibians are cold-blooded animals. Cold blooded-animals aka ectotherms are animals at the mercy of the temperature in their habitat. When it is hot in their habitat/ surroundings, they become hot and when it is cold in their surroundings, they become cold. In hot environments, cold-blooded animals such as amphibians can become hotter than warm-blooded animals. So just because some animals are referred to as cold-blooded animals, it does not mean that they cannot get as warm as warm-blooded animals.
Perhaps the most surprising thing about cold-blooded animals to many people is the fact that they actually like warm surroundings. Most cold-blooded animals are much more active in warm weather than in cold weather. This is because the chemical reactions they need for muscle contractions and movements happen faster in warm weather than in cold weather.
So amphibians are cold-blooded and not warm-blooded. They take on the temperature of the place where they are.
The Difference between Cold-Blooded Animals and Warm-Blooded Animals
Cold-blooded animals including amphibians take on the temperature of their surroundings. So they are at the mercy of the environment. In contrast, warm-blooded animals such as birds and mammals do not take on the temperature of their surroundings.
They generate their own heat by converting the food they eat into heat energy. They generate their own heat especially when it is cold. When it is warm, they cool themselves. So unlike cold-blooded animals, they are not at the mercy of the environment.
How Do Cold-Blooded Animals Regulate Their Body Temperature?
When it is cold, cold-blooded animals including amphibians try to increase their body temperature by basking in the sun and increasing their rate of metabolism. They respond as stated above because if they don’t, they will become too cold to survive.
To ensure they get maximum warmth from the sun to warm up, cold-blooded animals usually lie perpendicular to the rays of the sun. Some of them can also darken their bodies to absorb more heat from the sun.
When it gets too cold during winter, some cold-blooded animals including amphibians such as frogs are known to regulate their body temperature by hibernating.
Hibernating involves the animals hiding in warm places such as crevices, underground, and mud and going into a deep sleep. This reduces their exposure to cold weather and surroundings and prevents their body temperature from going too low.
When it is too hot, cold-blooded animals including amphibians usually respond by staying underwater if they can, going into shaded areas, or positioning themselves parallel to the rays of the sun to reduce their exposure to heat from the sun.
They do these things to cool themselves because if they don’t, they will become too hot to survive. Some cold-blooded animals are also known to dig into and bury themselves in cool soil, while others sit with their mouths wide open to lose heat via evaporation.
As you can see from the information above, cold-blooded animals use clever ways to warm up when it is cold and to cool down when it is hot. This is because they cannot maintain a constant body temperature like warm-blooded animals.
What is also clear from this section of this post is the fact that cold-blooded animals are just cold by name. They do not like cold environments or surroundings. When the weather or their environment gets cold, they respond in one way or the other to warm up.
Amphibians and Their Habitat
As stated earlier in this post, in contrast to other animals, amphibians like living near constant water bodies. This is what makes it possible for them to quickly cool down when it becomes too hot. This is because water bodies are almost always cooler than their surroundings.
Habitat Loss and the Extinction Crisis
As mentioned above, amphibians like living near constant water bodies. They do this because they need water to survive. They need it because they drink it and because it provides them with food in one way or the other. Most importantly, they need water to regulate their body temperature since they are cold-blooded animals.
However, because of human population pressure and climate change, constant water bodies around the globe are shrinking and disappearing. They are also being heavily degraded. All these things now mean that many amphibian populations can no longer cool off or find food as they did before. This is significantly reducing their numbers and making some of them extinct.
As of now, it is estimated that nearly 200 known amphibian species are already extinct. Nearly 2,000 species are also threatened by extinction especially due to habitat loss and other reasons such as the capture of wild amphibians for keeping as pets.
You can play an important role in preventing the extinction of amphibians. You can do so by supporting initiatives to prevent the extinction of amphibians and by not collecting or buying wild amphibians to keep as pets.
Amphibians are cold-blooded. This means they take on the temperature of the environment. Therefore, when it gets too cold they get too cold and they must respond to warm up. And when it gets too warm they get too warm and they must respond to cool off. If amphibians don’t respond to cool off or warm off their survival could be threatened.