Iguanas are constantly labeled as amphibians, but that is incorrect. Amphibians and reptiles look awfully similar because of their body types and colors, and although the terms are frequently used interchangeably, they are not the same.
Iguanas are ectothermic and arboreal reptilia (reptiles). They hatch from eggs which were laid on land and undergo a process of thermoregulation for their entire lives. Both reptiles and amphibians are classified as vertebrates because they contain a backbone, but unlike amphibia (amphibians), iguanas do not live in the water nor do they breathe through their skin.
Most people believe the only difference between reptiles and amphibians is simply the fact that one group lives in the water while the other does not. However, it’s a bit more complicated than that. There are a plethora of reasons why iguanas are classified as reptiles and not amphibians.
Why Are Iguanas Considered Reptiles And Not Amphibians
As I previously stated, iguanas and amphibians have more differences than they do similarities, some of which blew my mind when I first read about them. I think you’ll be just as surprised as well.
Iguanas Have Lungs
Probably the craziest thing I learned about iguana and amphibian differences is the fact that the latter breathe through their skin. Yup, you read that right.
Amphibians have a moist and porous skin which allows them to take in oxygen, making them extra susceptible to toxins in the water. Some amphibians don’t even contain gills or lungs, rendering them completely dependent on their skin for oxygen.
On the contrary, iguanas have lungs just like you and I. They breathe in oxygen through their lungs and expel carbon dioxide.
Generally speaking, iguanas have more advanced respiratory and circulatory systems than amphibians.
However, iguanas can swim underwater by using their tails as propellers, and can hold their breath for an impressive fifteen minutes, sometimes longer.
For more info, check out this post I wrote about iguanas knowing how to swim.
Iguanas Lay Eggs On Land
Iguanas fertilize their eggs during copulation, and proceed to lay their eggs on land while amphibians lay their eggs in the water and are not fertilized until after they are laid.
Female iguanas dig holes during breeding season, lay their eggs, and cover them back up with dirt. Detecting iguana nests is pretty simple, as they look like dirt mounds near a river bank.
Furthermore, iguana eggs are considered to be amniotic, meaning the egg has a hard shell and an extraembryonic membrane. Amphibian eggs are called spawn, and are soft and jelly-like.
Iguanas Have Scales
This one came as a big surprise to me as well. Apparently, amphibians do not have scales. Instead, they have smooth and thin skin which makes it easier from oxygen to be exchanged with blood vessels. Some amphibians also have the ability to produce toxins thanks to glands in their skin.
Iguanas have rough horn-like scales which allows them to retain moisture and protects them from the environment.
Depending on the temperature, an iguana’s skin can change from a lighter to darker shade of green.
Iguanas Are Arboreal
Iguanas are arboreal animals, which means they spend most of their time living in trees. More specifically, iguanas like to hang out on branches that are suspended above a body of water in order dive into the river or lake at the first sign of danger, such as the threat of a hawk.
Did you know iguanas have three eyes which use to detect hawks that dive down on them from above. Check out this post I wrote about iguanas and their third eye to learn more.
Amphibians are not terrestrial or arboreal, they are amphibian, which means they dwell on both land and water.
Iguanas Do Not Undergo Metamorphosis
Amphibians undergo metamorphosis, which is a four-phase process that involves great physical transformation and preparation of an aquatic larval stage for terrestrial life as adults. For example, the change from tadpole to frogs.
Iguanas, on the other hand, do not undergo any type of metamorphosis. They simply mature into adulthood the same way humans and most mammals do.
Iguanas Don’t Care For Their Young
Female iguanas may stay next to her burrow for a day or two after laying her eggs, but only to protect her eggs from rival female iguanas. Iguanas do not care for or protect their offspring.
Once the baby iguana has hatched out of its egg it is completely alone against the rest of the world, which is why the vast majority never get to see adulthood.
However, amphibians are known to protect and transport their eggs, hatchlings, and juveniles.
Similarities Between A Reptilian Iguana And Amphibians
With the exception of their outward appearance, I would argue that iguanas and amphibians are more different than they are similar. However, that doesn’t mean they don’t have anything in common.
Below are a few similarities between iguanas and amphibians.
Iguanas And Amphibians Are Cold-Blooded
Both types of animals are ectothermic, which means they must obtain heat from an external source. In the wild, iguanas and amphibians bask in the sun to increase their body heat. Without the sun, neither would survive.
In captivity, they are completely dependent on an electric heat source, usually a lamp. However, not all artificial heat sources are created equal, and some can even kill your pet. Check out this post for more info on iguanas and heat lamps or click this following link to learn more about iguanas being cold blooded.
Iguanas And Amphibians Are Vertebrates
Iguanas and amphibians both contain a backbone, also known as a spine. Thus, classifying them as vertebrates. As an example, animals that are not classified as vertebrates include jelly fish, insects, star fish, and arachnids (spiders).
Iguanas And Amphibians Have Similar Appearances
Probably the number one reason why people mistake iguanas for amphibians is simply due to the way they look. Many amphibians, such as newts and salamanders, give off a very lizard-like appearance.
With the exception of amphibians’ moist-like skin, both reptiles and amphibians seem to have the same type of skin at a first glance, but that is most definitely not the case.
Last but not least, iguanas can be very bright green or blue just just like some amphibians, resulting in another reason why they are mislabeled.
Iguanas And Amphibians Can Regenerate Their Tails
Probably the coolest thing about iguanas and amphibians is their ability to regrow their tails after either personally detaching it or after a close encounter with a predator who ripped it off.
According to James Hatfield in his book, Green Iguana The Ultimate Owner’s Manual, iguanas detach their tails in process called caudal autonomy. However, the ability to fully regrow their tail depends on the iguana’s age.
Younger iguanas can more easily regrow their complete tails, and do so faster as well, while adult iguanas may only regrow part of the tail, grow it back slower or even in a slanted angle.
While the same can be said for amphibians and their tails, some, such as newts and salamanders, can regrow more than just their tails. They can also regenerate complex organs such as certain parts of the eye, brain, heart, and even their limbs.
Did your iguana’s tail fall off? Check out this post I wrote which teaches you exactly what to do if your iguana is in the process of regenerating its tail.