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Monitor Lizard

Last updated date: 16th Apr 2024
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An Introduction to Monitor Lizard

Monitor lizard consists of 60 living species of large lizards of the family Varanidae and genus Varanus. Monitor lizards prefer tropical and subtropical zones of Asia, Africa, and Australia. Monitors are the advanced lizards of their species in comparison to an active and predaceous lifestyle. Komodo dragon, scientific name: Varanus komodoensis is the largest species of monitor lizard and the largest lizard present in the world. Dragon monitor lizard is 3m in length and weighs 135 kg.


Dragon monitor lizard is an endangered species that is only found on small Indonesian islands. But Megalania is twice as long as the size of a Komodo dragon lizard. Megalania is found in Australia as fossils. The smallest monitor lizard is Varanus brevicauda found on the western side of Australia which is 20cm long and weighs 20gm. Monitor lizards have an elongated head, elongated neck, well-developed legs, and neck. All the species present in the Varanus family are carnivores and also consume insects and spiders except V.bitatawa and V.olivaceus. 

So, without any further delay let's start learning more about the gigantic monitor lizards and understand everything about them!!

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What is a Monitor Lizard?

Monitor lizard is a Reptilia of the kingdom. Animalia belongs to the Varnanida family. It is found in Africa, Asia, and Oceania. The monitor lizard size is 20cm. It preys on rodents, snakes, and lizards. They prefer to live in coastal forests and riverbanks. They lead a solitary lifestyle.

Some Interesting Monitor Lizard Facts

  • Monitor lizards are the most intelligent compared to all the other lizards and compared to all the other reptiles in general.

  • They are terrestrial as well as semi-aquatic as well as arboreal in life depending on the types of monitor lizard species.

  • They have hind legs for the detection of their predators.

  • A monitor lizard has very good vision. Thus, they don’t blink their eyes. Many scientists have seen monitors watching airplanes in the sky.

  • A monitor lizard has a high rate of metabolism.

  • Most of the monitor lizards are covered with scales in green, brown, or grey color.

  • Monitor lizards burn energy like mammals.

  • If you pet monitor lizards, they are attention-seeking reptiles and always wanting to play reptiles.

  • They are high-skill and alert predators.

  • Monitor lizards are mainly carnivorous animals but they are also omnivores who eat fruits, plants, etc.

  • Among peculiar Monitor lizard facts one is that they communicate with themselves by body postures, sound, and sounds. A hissing sound is heard when the monitor lizard is threatened.

  • Like other lizards, they too fail to regenerate their tail if it is cut off.

  • Enemies of monitor lizards are snakes, wildcats, and humans.

  • They have a life span of eight to thirty years.

Types of Monitor Lizards

A monitor lizard has different types of local names based on the places they live.  Few are living, few are endangered and few are vulnerable in types of monitor lizard. Some different types of monitor lizard lower classifications are as follow:

  • Bengal Monitor

  • Gray’s monitor

  • West African Nile Monitor

  • Black-throated monitor

  • Blue-tailed monitor

  • Savannah monitor

  • Timor tree monitor

  • Crocodile Monitor 

  • Ridge-tailed monitor

Biology of Monitor Lizards 

Monitor lizards are known for their massive body size and powerful legs. Most species of monitor lizards have strong claws in their feet. Out of all the largest monitor lizards can climb trees well. Their tails are powerful and long. The monitor lizard size tail is twice as long as their body size. They grow throughout their lifespan. So, the largest one is the oldest one. 

They also have long tongues which have a bifurcated tip that is highly sensitive to smell. The tongue can pick the smell of chemicals and then retract them into the mouth with the smell they analyze using their organ on the roof of their mouth. A monitor lizard has a replacement tooth that grows in between the gaps of mature teeth. They have a total of 29 vertebrae just above their hips. Nine vertebrae are neck vertebrae.  Their heads are tapered and have distinct ear holes.

Monitor lizard is one of the active predators who hunt during the day. They explore a wide range of animals and eat their eggs and carrion. Monitor ingest small prey. Monitor lizard is a cold-blooded animal known as poikilothermic. When they have been heated by the morning sun, they are more energetic as their muscles work much more easily. Monitors are fast runners when they chase their prey. Monitor lizard is also a good swimmer who seeks water as a refuge. They can walk underwater and they use their tongue to smell.

Species of Monitor

In Africa, the Nile monitor is found as an aquatic species. In the southern part of Asia, the Bengal monitors are found. The Bengal monitor is also found in Iran and Afghanistan to Java in Indonesia. Bengal monitor is a terrestrial lizard that becomes dormant during the time of extended drought. The two-banded monitor is a largely aquatic species that has a size of 3cm and is found from Bengal and Ceylon through Southeast Asia. The giant monitor has a size of 2.4m and it is among the seventeen species of monitors which are found in Australia.

Monitor Lizard and People

Monitor lizards are used for their meat, skin, and eggs. In Chinese tradition, they use the fat of the monitor as medicine. Monitors have lost their natural habitat in many areas and places. Some of the Indian monitors died by eating cane toad. The cane toad has a highly toxic chemical that secretes from a large gland on the side of the neck which is poisonous to the predators that attempt to eat the toad.

The Appearance of Monitor Lizards

There are various types of monitor lizards of different sizes and appearances. The smallest monitor lizard is eight inches in length. While several other large species of monitor lizard size vary from seven to ten feet. Despite the different sizes of different types of monitor lizards, they have thick solid bodies with long necks, well-developed legs, and long tails.

The Behavior of Monitor Lizards

Monitor lizards are known as solitary reptiles. While in few areas with limited water resources the monitor lizard comes together as a group of 25. Naturally, they lead solitary lifestyles and only come together to breed. Monitors are mainly terrestrial and move on land mostly with larger species. There is the presence of few arboreal and aquatic species of monitor lizard as well. Though monitor lizards are carnivorous animals, they are shy of humans. But if you provoke them, they can be dangerous. They are faster than you think, have strong jaws and powerful tails. Monitor lizards are aggressive when it comes to their territory and food. Most of the monitor lizards are active hunters who will carefully stalk and chase their prey down. While the remaining other monitors prefer scavenging.

Monitor Lizards Reproduction and Lifespan:

Males fight with females to mate. The dragon monitors lizard mates during the month and between May and August and they lay eggs around September. Female lizards show antagonistic behavior toward male lizards. So, for mating, they need to restrain them or else male lizards might get hurt. Monitor lizards lay their eggs in a concealed nest in the ground. They also lay in the hollow of tree stumps. The method may differ from different species of monitor lizard. For example, Komodo dragons can lay their lays on the nest which is abandoned by other birds or they lay inside the hole of hills and ground. 

Few species of monitor lizards lay 30 eggs while dragon lizards lay 20 eggs. The holes are covered by termites naturally to secure and provide warmness to eggs. When the young lizard hatches, they eat the termites before leaving their mound. The young monitor lizards and many unhatched eggs are attractive for predators. So, the young ones spend their life in trees to prevent themselves from predators. Most of the monitor lizards have a life span of 20 years while the Komodo dragon takes nine years to mature fully. They live up to 30 long years. Smaller species of monitor lizards tend to live more than larger species of monitor lizards.

Monitor Lizard Predators and Threats:

Humans are the main predator of the largest species of these monitor lizards. While some other types of monitor lizards are hunted to use their skin in the leather trade. But the Komodo dragon monitor lizard has rugged and rough skin that can’t be used as leather. So, they are not preferred for leather trades. But for all the other types of monitor lizards, especially the young ones’ prey on by other types of lizards, snakes, fishes, large birds, and big cats. 

While smaller lizards are preyed on by animals in an adult stage as well as in the young stage. The status of conservation depends upon the species. For example, the Komodo dragon monitor lizard is vulnerable while the Asian water monitor is not much a cause for concern when it comes to its conservation status. While the Panay monitor lizard is endangered. Many monitor lizards lose their habitat due to threats like decreasing water bodies and hunting from humans to use for their benefit.

The Population of Monitor Lizards

In this world, 80 species of lizards are present out of which one species is the monitor lizard which includes 60 living monitor lizard species. The smallest lizard lives in trees and water so they are really hard to determine which makes their population data unknown most of the time. For example, a rare earless lizard has unknown data of population.  The small range of monitor lizards is vulnerable due to their small size. But earless are nocturnal species of monitor lizard and this is why it is not much seen by people. The largest species like dragon lizards are kept protected as their numbers are dwindling in few areas. Loss of habitat and food resources as well as decreasing water bodies is the main reason for the monitor lizard’s less population. If there will be a sufficient amount of water bodies, food resources, and habitat they may tend to increase.

FAQs on Monitor Lizard

1. What is the Monitor Lizard Diet and What Does it Eat?

Ans: The diet of monitor lizards depends upon the lives and depends upon the size and type of monitor lizard. The monitor which lives in the tree eats insects and birds. Few tree monitors eat mainly fruit. The monitors which live in water eat whatever they find in the water. It consists of fish, water birds, eggs, insects, and water mammals. The terrestrial lizards such as the Komodo dragon monitor lizard eat a variety of carrion and their prey. The diet of dragon monitor lizards has 50% of deer native to the island. They also prefer to eat cattle and pigs if they find them. They are known as opportunistic predators.

The large monitor has predators. Small and baby monitors can be eaten by birds, a few other reptiles and lizards, wildcats, and humans. They have various kinds of fruit, mammals, fishes, insects, and reptiles.

2. How Does the Monitor Lizard Survive?

Ans: Monitor lizard lives in different places from trees to desert to inside water bodies. In trees, they blend themselves to the color of leaves and the color of brown or blend in the color of the trunk. Few lizards have green flat tails like leaves. In the desert they adapt themselves to walk and run over sands, their toes fringed with spiny scales. 

Many of them burrow themselves in the sand as an escape away from the intense heat of the desert and to prevent themselves from predators or they stalk small animals to prey upon them. Most of the lizards who prefer borrowing have clear scales on their eyelids that protect their eyes. While in water they tend to spend time in the water where there are chances of finding food or fish or to hide from land-dwelling predators. In between their toes, they have webs of skin to help them to swim.