Wildlife SOS introduces a new series “Things You Didn’t Know About” that explores fascinating and lesser-known facts about various species. Our writers will spotlight one aspect of the wild, unveiling its unique characteristics and roles in the ecosystem. In this feature, we shed light on a family of lizards often likened to real-life Godzillas — monitor lizards.
Hollywood movies have always given us a glimpse of giant lizards and their extraordinary capabilities, ranging from the film Godzilla (1998) and the Indiana Jones series, to the recent Amazing Spider-Man series. As fiction is often rooted in reality, nature is replete with various species of large lizards that have served as inspiration.
Monitor lizards are oviparous (egg-laying) reptiles native to Africa, Asia, and Oceania. Currently, as many as 86 species are recognised, and India is home to four: the Bengal monitor lizard (Varanus bengalensis), the Asian water monitor (Varanus salvator), the yellow monitor (Varanus flavescens) and the desert monitor (Varanus griseus). The Bengal monitor lizard is the most widely distributed species of this carnivorous reptile in the country, while the Asian water monitor has the greatest build among the four.
Diversity in Size
While monitor lizards are renowned for being colossal, their size, in fact, varies across species. The smallest species of monitor lizards, the short-tailed pygmy monitor (Varanus brevicauda), is native to Australia’s arid regions and reaches a tiny length of just 25 cm. The ackie monitor, also called spiny-tailed monitor (Varanus acanthurus), is found in North West Australia, and can grow to an average length of 24-28 in. In contrast, the Komodo dragon (Varanus komodoensis), found in Indonesia, is the largest extant lizard species, capable of reaching a length of 3 m, a whopping 10 feet! The Asian water monitor (Varanus salvator) comes in at a close second to this, with its species measuring 9-feet-long.
This dramatic range in size highlights the diverse adaptations and ecological niches occupied by monitor lizards. Their native environment also guides their dietary inclinations. While all species of monitor lizards are carnivorous, research has found two species as exceptions. The Northern Sierra Madre forest monitor (Veranus bitatawa) and the Gray’s monitor (Veranus olivaceus) found in the Philippines are frugivores.
‘Snakes’ of the Lizard World
Although monitor lizards are referred to as “lizards”, herpetologists suggest that they are more closely related to snakes. This connection is due to their shared evolutionary lineage within the order Squamata, which encompasses both lizards and snakes. Like all reptiles, monitor lizards too are cold-blooded or ectothermic animals, but there is one striking feature monitor lizards have that is akin to snakes — a forked tongue. The Varanidae family of lizards utilises its bifurcated tongue exclusively for a sensory function called chemoreception. The monitor lizard continually pushes out its tongue, flicks it to take in odour molecules from their surroundings, and rolls it back in. The chemical samples collected through this act are transferred to the Jacobson’s organ present on the roof of the mouth. As a well-developed olfactory apparatus, this organ is helpful for monitor lizards to detect prey (even if it is underground or well-hidden), predators and other members of their species. Chemoreception significantly aids in determining a potential mate for the monitor lizard as well.
Another similarity is that like snakes, monitor lizards too have venom glands. While they use these only to subdue small prey, their venom is not fatal to humans. It is advisable, however, to contact the nearest forest officials or a wildlife organisation in case you encounter a monitor lizard in your vicinity, so that a careful and skilful rescue can take place.
Tales of Tails!
Monitor lizards have powerful and versatile tails that serve varied functions depending on the species. Their tails usually grow to be more than half of their body length, making it a mighty tool they can use in defence. Another fascinating fact about this robust organ is how it can store fat at its base. Monitor lizards rely on this storage to survive when there is scarcity of food in their environment. Interestingly, unlike the delicate tails of lizards like iguanas and geckos, monitor lizard tails are made up of a strong composition which cannot regrow to their original length in the case of any damage or loss.
For semi-aquatic species like the Asian water monitor, their tail becomes as useful as a rudder when they navigate underwater. Their laterally compressed tails help them to glide comfortably, and even trap fishes while foraging. The arboreal emerald tree monitor, found on the islands of New Guinea, also makes the best use of its prehensile tail to adeptly grasp branches while climbing trees!
Threats to the Monitor Lizard
Covered in a mosaic of scales in tan, green, grey or brown, monitor lizards are highly coveted by humans for their thick skin, which makes the species susceptible to wildlife trafficking. Their hides are used to craft drums, while their flesh and eggs are considered delicacies and are believed to possess aphrodisiacal properties.
Monitor lizards of India are protected under Schedule I of the Wildlife (Protection) Act, 1972, yet, they face a threat to their survival due to the rampant illegal trade of their genitalia. The hemipenis (sex organ) of a monitor lizard closely resembles the roots of a rare plant called hatha jodi. The plant root is believed to have magical properties that can bestow happiness on their owners. In the name of this superstitious belief, monitor lizards are mercilessly targeted and exploited.
Despite their declining habitats at present due to human encroachment, monitor lizards possess remarkable biological capabilities that have allowed them to persist through the ages. To safeguard various animal species, Wildlife SOS operates 24×7 emergency rescue helplines across four regions in India. If you encounter an animal in need of assistance, please reach out to us immediately:
Delhi NCR: +91 9871963535
Agra: +91 9917109666
Vadodara: +91 9825011117
Jammu & Kashmir: +91 7006692300, +91 9419778280
