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Are Crocodiles Reptiles? (Or are they Amphibians?)

Crocodiles are classed as reptiles, not amphibians. The classification is due to several features of crocodiles including air-breathing lungs, land-based eggs and nests, and bony scales called scutes. All reptiles and amphibians belong to a superclass called herpetofauna.

A partially submerged crocodile

Alligators, snakes, and lizards are all reptiles. Reptiles typically have scales or a special kind of skin. They breathe air, and like amphibians, they cannot regulate their body temperature. 

Why are Crocodiles Considered Reptiles?

In taxonomy, a reptile or Reptilia is a cold-blooded animal. Reptiles, like mammals, breathe through their lungs. Reptiles lay eggs on land, while amphibians lay eggs in the water. Reptilians also have bony “skin” or scales.

The crocodiles fit this class as it lays their eggs on land. It also has lungs and must breathe above the water. The crocodile skin is not skin but a network of scales that scientists call scutes.

Reptiles are tetrapod vertebrates, which means they have four limbs. Despite this description, snakes are part of the reptile world because snakes used to have limbs—they descended from ancestors that have limbs. 

Reptiles are hardy creatures, but many crocodiles and alligators are now critically endangered.

Crocodile Swimming
Although crocs spend a lot of time in water, they are not considered amphibians

Reptilian Features of Crocodiles

Like most reptiles, crocodiles have bony scales, lay their eggs on land, and have air-breathing lungs. These characteristics and more separate them from amphibians and mammals.

Let’s look at some more features of crocs that place them squarely in the reptile class of animals:

1. Crocodiles Lay Eggs on Land

All reptiles lay eggs on land, including crocodiles. Crocs lay clutches of several eggs at once, usually once or twice per year.

Similar to other reptiles like turtles, crocodile eggs have a hard outer shell with a soft leathery internal shell to protect the baby.

By contrast, amphibians lay their eggs in water and their eggs are often soft and jelly-like, and mammals give birth to live young.

A juvenile caiman on some reptile eggs
Crocodiles and caiman lay hard-shelled eggs, similar to most reptiles

2. Crocodiles Have Lungs

A defining characteristic of reptiles is that they have air-breathing lungs from birth. Unlike amphibians, which may have gills and be able to breathe underwater, depending on their species and stage of development.

Although crocs breathe air, they are well-adapted to life in the water. They are adept swimmers and aquatic predators, and can hold their breath for up to two hours underwater to help them hunt fish.

Read More: What do Crocodiles Eat?

3. Crocodiles Don’t Metamorphize

Many amphibians go through a period of metamorphosis, completely changing their form from when they are a juvenile to when they are an adult.

Unlike amphibians, crocodiles are born in the same form as an adult croc, only smaller.

Metamorphosis is not possible in reptiles, and the lack of metamorphosis is one of the reasons scientists classify crocodiles as reptiles.

A tadpole swimming in a tank
Crocs are born fully-formed. Amphibians like frogs often go through a period of metamorphosis

4. Crocodiles have Individual Scales

One of the key characteristics that set reptiles apart from mammals, birds, and amphibians is the presence of individual scales.

White reptiles have scales, amphibians have soft leathery skin that must be kept hydrated, mammals have a covering of fur or hair, and birds have feathers.

Crocodile scales are called scutes, and are large and bony. These scales act as protection from the elements and would-be predators, while allowing the crocodile to maintain a high level of flexibility.

Other scaled reptiles include lizards, snakes, and turtles.

5. Crocodiles are Vertebrates

Similar to amphibians and mammals, all reptiles are vertebrates. This means they have a backbone that protects their spinal cord, a skull to protect their brain, and four limbs.

Snakes are also considered reptiles and vertebrates, as although they don’t have visible limbs today, they evolved from tetrapod vertebrates and have four non-visible residual limbs.

Lolong the Crocodile - Skeleton
Crocodiles are vertebrates, like all reptiles. They have a spine, skull, and four limbs.

6. Crocodiles are Cold-Blooded

One of the reasons crocodiles are considered reptiles is because they are cold-blooded. This means that they have no internal mechanism to regulate their body temperature and rely on their environments to heat themselves up or cool themselves down.

This is true of all reptiles and amphibians (together called herpetofauna), including crocodiles.

Are all Crocodilians Reptiles?

All crocodilians including crocodiles, caiman, alligators, and gharials/gavidals are all reptiles.

All crocodilians belong to the taxonomic class ‘Reptilia’ which contains every reptile.

Summary – Are Crocodiles Reptiles?

Crocodiles are reptiles. They are cold-blooded animals that cannot regulate internal body temperature. Instead, they rely on their environment to maintain homeostasis.

Crocodiles are not descendants of dinosaurs. Instead, they are descendants of the archosaur. The crocs today have three distinct families, but they all belong to the same order of Crocodilia.

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