The monitor lizard is one of the most interesting species in the world. From their formidable hunting skills to their awe-inspiring ability to conquer diverse landscapes, they keep surprising us. Let’s have a look at monitor lizard facts to know more about their untamed allure, where each moment holds the promise of a thrilling encounter!
Class: Reptilia
Order: Squamata
Family: Varanidae
Genus: Varanus
1. They have a snake-like tongue
The monitor lizard is a sizable reptile that belongs to the Varanidae family. It comes from Asia, Africa, and Oceania. It is believed that this group of lizards originated in Asia approximately 65 million years ago with a diverse array of characteristics and adaptations.
There’re about 79 species of monitor lizards in the world. They all have similar physical characteristics, but their size is varied. Among them, the Komodo dragon (Varanus komodoensis), a.k.a the Komodo monitor, stands as the largest species, having a size of over 10 feet (3 meters) in length. The Asian water monitor (Varanus salvator), commonly known as the water monitor or Malayan water monitor is the second largest species, while the smallest species measures approximately 7.9 inches (20cm).
These lizards possess a substantial body that is adorned with scales that display a range of colors, including grey, green, white, red, yellow, brown, or tan. Their head takes on a conical shape, complemented by a long and slender neck. With round pupils framed by eyelids, formidable jaws, and a robust tail measuring approximately two-thirds the length of their body, these lizards possess impressive physical features.
One remarkable trait of these lizards is their snake-like tongue, which is both lengthy and forked. Additionally, they possess well-developed limbs and powerful claws, enhancing their strength and agility.
Here are some types of monitor lizards: the Nile monitor (Varanus niloticus), the crocodile monitor (Varanus salvadorii), Merten’s water monitor (varanus mertensi), Dumeril’s monitor (Varanus dumerilii), spiny-neck monitor (varanus spinulosus), Solomon island mangrove monitor (Varanus indicus), Gray’s monitor (varanus olivaceus), and quince monitor (varanus melinus).
Or black roughneck monitor (varanus rudicollis), black tree monitor or Beccari’s monitor (varanus beccarii), silver monitor (varanus zugorum), rock monitor (varanus albigularis), yellow-headed or phillipine water monitor (Varanus cumingi), pibara rock monitor (varanus pilbarensis), golden-spotted tree monitor (Varanus boehmei), Samar water monitor (varanus samarensis), Palawan water monitor (Varanus palawanensis), emerald tree monitor or green tree monitor (Varanus prasinus),
Or blue-spotted tree monitor or blue tree monitor (Varanus macraei), desert monitor (Varanus griseus), lace monitor or tree goanna or Bell’s phase lace monitor (Varanus varius), perentie monitor (Varanus giganteus), yellow-spotted monitor a.k.a Argus monitor (Varanus panoptes), white-throated monitor (Varanus albigularis albigularis), sand goanna or Gould’s monitor (Varanus gouldii), ornate monitor (Varanus niloticus ornatus).
2. Habitat
Monitor lizards, renowned for their extensive presence across multiple regions, can be found in Africa, central and southern mainland Asia, Malaysian and Indonesian islands, Australia, Papua New Guinea, and even the Americas, where they have become invasive species.
These reptiles have evolved to live in a wide array of environments, ranging from jungles and rainforests to mountainous terrains to agricultural landscapes, from hot and arid areas to coastal locations and aquatic regions.
Take the Asian water monitor as an example. These water monitors exhibit a preference for semiaquatic environments, such as coastal areas, mangroves, and swamps. Interestingly, they have also demonstrated their adaptability by thriving in canal systems, as evidenced in Sri Lanka.
Contrasting with the water monitors, the Timor tree monitor belongs to the group of arboreal monitors. These creatures spend the majority of their time in trees, climbing through branches with their long tails and sharp claws.
3. Diet
Monitor lizards are carnivorous reptiles that consume various food, such as insects, eggs, birds, small mammals, and fish. In addition, certain species have been observed feeding on fruits and vegetation.
These reptiles demonstrate a wide-ranging foraging behavior, encompassing expansive hunting territories. In the wet season, they eat a diverse range of prey in large quantities, accumulating fat reserves to sustain themselves during the lean periods of the dry season.
Various species of monitor lizards have developed unique methods to acquire specific prey. Whichever strategy, they all depend on their acute senses and cleverness.
For example, instead of attempting to enter through the entrance, some creatures opt for a more direct approach by digging underground tunnels to reach the eggs. Meanwhile, others use their tails to push fish into shallow water, making it easier to capture them. Some skillfully intercept the escape routes of their prey like lizards, bypassing their zigzag patterns or accurately predicting their movements towards objects or trees.
They can even cooperate with each other to get the eggs of crocodiles. One lizard skillfully redirects the mother’s focus, allowing its partner to clandestinely pilfer the eggs. Some apply ambush strategy by freezing in a hunting stance, waiting for the prey, and catching them.
After getting the prey, these lizards firmly grasp their prey with their powerful jaws, subsequently unleashing a venomous secretion from their saliva to immobile them. After that, they withdraw to hidden areas where they proceed to consume their catch.
In adopting this strategy, they effectively conceal themselves as potential targets and safeguard the secrecy of their favored hunting grounds. This distinctive behavior distinguishes them from other members of the lizard family.
Monitor lizards, aside from their diverse dietary preferences, exhibit a rapid metabolism that prompts them to consume food frequently. This characteristic places them in closer resemblance to snakes rather than conventional lizards.
These creatures have numerous predators, such as crocodiles, pythons, king cobras, tigers, eagles, and humans. Smaller species and juveniles fall prey to predatory fish, snakes, herons, and even adult monitor lizards.
4. Adaptions
Monitor lizards exhibit a remarkable olfactory sense thanks to their forked tongues. They possess the ability to discern whether a snake has venom or not from a very far distance. They can also differentiate the gender and territorial status of other monitors by sampling chemicals in the air or inspecting tracks.
Unlike other lizards, they can’t regenerate their tails if they are lost.
Besides the keen sense of smell, these species have remarkable vision with unblinking eyes. This enables them to discern potential dangers or harmless entities even from considerable distances. The young monitor lizards have been reported to see aircraft flying at an altitude of 35,000 feet.
These lizards possess a distinctive respiratory system that allows them to breathe while in motion. Their throat contains specialized bones that form an air storage cavity. As they move, the lizards constrict their throat, pumping the stored air into their lungs.
Their skin is quite thick, making it hard for the cobra’s fangs to get through. That’s the reason why people say monitor lizards are immune to cobra venom.
5. They are active animals
These creatures exhibit remarkable speed while walking and they can cover long distances. The male monitor lizards have been observed roaming across expansive territories spanning ten square miles, whereas the females tend to cover approximately one-third of that expanse. While walking, they survey their environment by swaying their heads back and forth and flicking their tongues downwards to detect motion or detect odors.
Moreover, monitor lizards possess impressive swimming abilities, employing their robust tails for propulsion. They have been seen swimming in the ocean, traversing remarkable distances exceeding 30 miles.
However, when faced with limited food resources, they will conserve their energy by maintaining a motionless state for prolonged durations. You can see them inhabit a single tree for as long as 72 consecutive days, exhibiting minimal movement between branches.
6. Behavior
Monitor lizards are predominantly land-dwelling creatures, although they can also be encountered in trees or as partially aquatic species. They usually prefer a solitary lifestyle, however, there have been instances of them congregating in clusters of up to 25 individuals, particularly in regions where water is scarce.
These species are territorial, often displaying aggression through tail lashing and throat inflation accompanied by loud hissing. They also resort to hissing as a defensive reaction when threatened.
When compared to other reptiles, monitor lizards stand out with their exceptional intelligence. In captivity, they can be trained to count up to six, showcasing their cognitive prowess. In their natural habitat, they display impressive memory skills by recalling their hiding spots and the intricate pathways leading to them.
To communicate, they predominantly depend on their movements and posture, which are accompanied by various vocalizations like sneezing sounds.
These species are not dangerous to humans. However, they may attack and bite you if provoke or feeling threatened. You shouldn’t worry too much because their venom cannot kill you.
7. Reproduction
The mating season of monitor lizards takes place in the dry season. During this time, the females go through the estrus phase for about 1 – 2 weeks. The males become more active and engage in competition to secure the chance to mate with receptive females before other rivals in the vicinity.
To attract potential suitors, the females strategically position themselves in noticeable spots like tall trees, releasing a pheromone that can be detected from a distance of up to one mile.
Male monitor lizards exploit this chance by exploring the home ranges of several females. In certain instances, a solitary male was seen traversing the territories of four females in just 45 minutes, accomplishing successful mating with two of them.
However, some monitor lizard species, like the giant Komodo, can do sexual or asexual reproduction. It can reproduce on its own and lay eggs without a mate.
After mating, females go through a gestation period of about 5 weeks. Then, they will deposit approximately 50 eggs in underground nests. In certain species, such as those that lay their eggs in termite mounds, the females will return to these mounds approximately nine months later to enable the hatchlings to emerge.
Since they haven’t consumed much food for months, the females must use their fat and nutrient reserves to nourish their offspring. It is not unusual for them to experience a weight loss of around 15 pounds to 9 pounds after laying eggs and incubating them.
Those eggs will be incubated for about 4 months and hatch in the middle of the wet season. These babies exhibit a distinctive characteristic with their heads being disproportionately larger than their bodies, encompassing approximately one-fourth of their total length (excluding the tail). This grants them the ability to eat prey that is as big as them.
To survive in the harsh world, the young own exceptional visual abilities and an acute sense of smell as adults. Despite these advantageous traits, these juveniles still face dangers from raptors and snakes. Only one-third of them manage to survive until the first year.
The average lifespan of monitor lizard species falls within the range of 8 to 30 years.
8. Conservation status
Despite being primarily classified as the least concern species on the IUCN Red List, monitor lizards are currently experiencing a worldwide decrease in their population. Some of them are listed as endangered species, like the Panay monitor (Varanus mabitang).
This decline can be attributed to several factors, including habitat loss, especially in proximity to human settlements, depletion of water sources, and human hunting practices for their meat and skin. Notably, their skin is sought after for the production of a percussion instrument called a kanjira, which is a member of the tambourine family and is used in carnatic music.
The reptile pet trade also contributes to the declining populations of lizards. The savannah monitor (a.k.a Bosc’s monitor) and Ackies monitor are two of the favorite species being kept as pets. They are small, docile temperament, affordable, and easy to handle. That’s why they make good pets.
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