So, how do iguanas differ from monitor lizards? Besides being among the largest and most tasking pet reptiles to care for, iguanas and monitor lizards are alike in many other ways. However, they also differ in numerous ways. For instance, iguanas are typically herbivores that rely on plant and fruit-based diets, while monitor lizards are largely carnivores that hunt and feed on small animals, fish, and insects.

Moreover, iguanas and monitor lizards have different native origins, inhabit different natural habitats, have different housing requirements, have different body compositions and physical attributes, and generally have a shorter life expectancy than monitor lizards. Furthermore, monitor lizards typically cost more than iguanas.

Would you like to understand these and many more differences between iguanas and monitor lizards? Stay with me.

12 Difference between Iguanas and Monitor Lizards

Iguanas and monitor lizards have several distinguishable differences. The most obvious ones include the following:

1. Diet

Their diet is the most identifiable and significant difference between iguanas and monitor lizards. While iguanas are herbivores that survive on plant and fruit-based foods such as leaves from shrubs, trees, flowering plants, and vines, monitor lizards are carnivores that feed on animal, insect, snake, crab, bird, and fish meats.

Due to their diet variation, iguanas and monitor lizards have differing stomach and digestive tract designs and structures. Monitor lizards have smaller stomachs designed to digest animal proteins, while iguanas have bigger and more complex stomachs and guts to work on fiber-rich plant foods.

Moreover, monitor lizards can eat any meat depending on the food availability, the lizard’s species, age and size, and ability to hunt. On the other hand, iguanas hardly need to hunt as they can almost always readily find nutritious plants, leafy green, fresh veggies, fruits, and vegetables in nature.

However, since iguanas and monitor lizards require high calcium intake to support wholesome health and functioning, household pet reptile specialists recommend providing both with calcium supplementation via dusting or gut-loading.

2. Ancestral Origin

Iguanas originated from the Central and South American continents in countries such as Mexico and Costa Rica, whereas monitor dragons are native to Asia, Africa, Australia, and most other regions.

3. Natural Habitats

Like many other reptiles, iguanas and monitor lizards inhabit various natural habitats worldwide. Both live in warm climates.

While iguanas naturally live in tropical and subtropical regions, monitor lizards typically inhabit a wider geographical expanse and often live in tropical and temperate climates.

Additionally, iguanas generally dwell in forested regions such as water-catchment areas and localities around water sources like streams, rivers, and lakes. Contrarily, monitor lizards thrive in arid and semi-arid areas such as savannas and deserts.

Despite the differences in their natural habitats, both iguanas and monitor lizards are expert climbers and swimmers, so they love exploring and basking in the sun.

4. Body Composition and Physical Attributes

Iguanas and monitor lizards have numerous similar physical characteristics, such as sharp claws, scaly bodies, and long tails. Nonetheless, body composition and physical attributes significantly differ between the two types of lizards.

Besides their different body sizes, iguanas and monitor lizards have many other physical differences. While iguanas are comparatively smaller than monitor lizards, they have longer snouts.

Another obvious difference in the physical attributes of these two types of lizards is their neck size.

Monitor lizards have very long necks, which give them a snake-like appearance and some extra reach when hunting small prey such as mice. In contrast, iguanas have shorter necks, resulting in a more lizard-like appearance.

Additionally, iguanas depict a more confident appearance than monitor lizards due to the dewlap below their chin. On the other hand, monitor dragons have a snake-like tongues and move in a more calculated manner than iguanas.

Furthermore, iguanas have eyes with moveable eyelids and round pupils on either side of the head and are built with stocky trunks and slender scaly tails along with a single row of spines running from the nape of the neck to the tip of their seat.

On the contrary, monitor lizards’ bodies are covered with brown, green, grey, or tan scales, have exceptionally long necks and powerful tails, and have a forked tongue akin to that of a snake. Moreover, monitors have well-developed limbs and sturdy claws for hunting.

5. Body Size and Weight

Iguanas and monitor lizards are relatively big reptile pets compared to other household reptile buddies like bearded dragons and leopard geckos. Nevertheless, the two types of reptiles have evident variations in their overall body size.

Iguanas typically grow up to four to six feet from the snout to the tip of the tail, whereas monitor lizards can reach up to ten feet. For instance, Komodo dragons are monitor lizards that can grow up to 3m in length.

Additionally, iguanas can weigh up to 20 pounds, while monitor lizards can reach a body weight of 150 pounds.

6. Housing Requirements

Like all other reptiles, iguanas and monitor lizards are ectothermic (cold-blooded), so their body temperature tracks with the temperatures in their surrounding environment.

Thus, both reptiles require a special enclosure with controlled conditions to survive and thrive in captivity. However, there are some variations in the housing requirements of each.

A monitor lizard typically requires a more spacious vivarium than an iguana, as monitors are generally bigger and more active. Monitor lizards need an exceptionally big enclosure, preferably around 5 feet by 4 feet by 4 feet.

On the flip side, iguanas can thrive in smaller enclosures as they’re naturally smaller and less active than monitor lizards. A baby iguana can do well in a 20-25 gallon tank, while adult iguanas thrive best in a terrarium measuring 12 feet long by 8 feet high.

For iguanas to thrive in captivity, their terrarium should have an ambient temperature range of 80-85 degrees Fahrenheit. On the other hand, ambient temperatures in a monitor lizard’s tank should stay between 85-90 degrees Fahrenheit for the lizard to survive.

Moreover, the basking spot for both iguanas and monitors should be around 94-100°F,while the tank should stay under temperatures between 74-78° F at night.

And that’s not all: Iguanas thrive in high-humidity locales, so it’s best to maintain a pet iguana’s tank humidity at 70-75% to ward off inconsistent shedding and kidney disease. Always keep a large and easily-accessible soaking tub and fresh drinking water for monitor lizards. 

Further, iguanas require an enclosure with many branches, hammocks, and other elevated platforms to climb, bask, and explore. Contrarily, monitor lizards need larger enclosures with plenty of hides.

7. Handling Recommendations

With the right care, diet, and attention, an iguana or a monitor lizard can be an exciting and rewarding household companion.

But there’s a catch- the pet reptile have utterly different handling recommendations: You should handle a pet iguana gently and carefully as the lizard can easily get stressed, resulting in a series of undesirable reactions such as tail loss, a dwindling appetite, emaciation, and general ill health.

On the contrary, you shouldn’t handle a pet monitor lizard for these reasons:

• They have exceptionally sharp claws and teeth that can easily pierce your skin, causing multiple effects like itching, pain, and infection.
• Monitor lizards are susceptible to getting aggressive and biting their handler.

8. Overall Cost of Purchase and Maintenance

If you compare the cost of buying and maintaining these pet lizards, their food, enclosure, and all furnishings, monitor lizards are considerably more expensive than iguanas. Let’s break down these cost comparisons a little further:

• The upfront price of buying a pet monitor lizard is far higher than purchasing a pet iguana. You can cheaply purchase a baby green iguana for as little as $20-$50, while some rare species and morphs of iguanas, such as rhinoceros and albino iguanas, go for a few hundred and a few thousand dollars, respectively. Contrarily, most common species and morphs of monitor lizards sell for a few hundred dollars depending on availability and other factors like health status and age. Surprisingly buying some of the rarest species and morphs of monitor lizards can cost upwards of $10,000.
• Feeding a pet monitor lizards is much more costly than feeding a pet iguana. While buying iguana food often costs around $30-$50 per month, stocking up on monitor lizard food can cost more than $100 monthly.
• Other maintenance costs, such as cleaning and vet care, are roughly the same for pet iguanas and monitor lizards.

9. Life Expectancy

Under ideal conditions, monitor lizards generally have a higher life expectancy than iguanas. Iguanas have an average life expectancy of 12-20 years, whereas monitors can easily clock 8-30 years.

10. Potential for Carrying Diseases

Remember, monitor lizards have sharper, more potent teeth and claws, so their bite or scratch can bring more pain and discomfort than an iguana.

But that’s only part of it, as monitor lizards pose a bigger risk to humans than iguanas as they carry more diseases.

Due to their carnivorous (raw meat-rich) diet, monitors carry more harmful bacteria in their mouths than iguanas.

Meat residues in a monitor lizard’s mouth harbor many harmful bacteria, making a bite from a monitor extremely hazardous. Then again, the worst bacterial infection you can get from an iguana’s bite is salmonella in rare occurrences.

11. Ability to Shed and Regrow the Tail

Iguanas can drop their tail when they’re extremely frightened. Fortunately, the tail grows back, although it might not regrow to its initial size, shape, and glory. Tail-shedding is an iguana’s built-in response to extremely scary or stressful situations.

Unlike iguanas, monitor lizards cannot drop and regrow their tail. If a monitor loses its tail, it stays without it for the rest of its life. Nevertheless, monitor lizards have other inbuilt responses to fright and stress, such as:

• A monitor lizard’s bite is a potent weapon against its enemies
• Some monitors have spikes that make incredible weapons against the lizard’s enemies.

12. Camouflage

Unlike monitor lizards that retain their body color throughout, iguanas have an innate ability for camouflage as they can change their body color to match the surrounding vegetation, landscape, or anything in their environment in the same way a chameleon behaves.

Final Thoughts

Iguanas and monitor lizards are similar in many ways, so they often sell as ‘exotic reptile pets.’ They both possess lovesome traits and fascinating behaviors, making them among the most-loved household reptile pets throughout the world.

Nevertheless, iguanas and monitors differ in many ways as well, including:

• Iguanas are chiefly herbivores that thrive on fiber-rich plant-based diets such as leafy greens, veggies, and fruits, whereas monitor lizards are primarily carnivores that rely on insect, animal, and dish meats to survive
• Monitor lizards typically grow bigger and heavier than iguanas, so monitors require more spacious enclosures
• Monitors carry more diseases via their bite than iguanas
• Overall, iguanas are cheaper in terms of upfront purchase and maintenance costs
• Iguanas are native to Central and South America, while monitor lizards have their natural habitats in Australia, Africa, Asia, and almost everywhere.

Overall, iguanas and monitor lizards are unique in separate ways. Thus, both can make fascinating household reptile buddies and liven up a bland house, depending on your preference.

Nevertheless, you must be ready to put in the hard work and time to feed, care for, and bond with the reptile to enjoy many years of companionship.