An earless monitor lizard on top of a rock

Earless Monitor Lizards: Everything You Need To Know

Earless monitor lizards are unique creatures that are sometimes kept as pets. But their lack of popularity means there’s a lot of misinformation being passed around when it comes to their care requirements.

This guide will teach you everything you need to know about earless monitor lizard care. Trust us, you’ll want to read this closely!

Species Summary

The earless monitor lizard (Lanthanotus borneensis) is a rare reptile with distinct care requirements. These animals are the only species in the Lanthanotus family, roughly translating to “hidden ear.” However, they are related to actual monitor lizards.

In the wild, the earless monitor lives on the island of Borneo, which is how it gets the “borneensis” part of its scientific name. The lizard’s distribution is relatively wide, spreading from East Malaysia to Western Indonesia. Even still, this species is pretty easy to miss.

It prefers rocky streams and marshes in the lowlands. Earless monitor lizards also live in degraded agricultural lands, such as palm oil plantations, fruit tree gardens, and rice paddies. They tend to go unnoticed, leading to questions about their vulnerability.

Expert Tip: Exporting an earless monitor lizard is currently against the law, as various protections are in place to keep wild populations safe. However, captive breeding has resulted in a modest amount of these being kept as pet lizards. These lizards are still relatively rare, making them a sought-after species for many collectors.

Appearance & Colors

This semi aquatic reptile has many unique defining features. Its body is textbook Monitor thanks to its cylindrical shape and short limbs. The legs are short and stubby, but the claws are sharp enough to grasp objects under the water.

The tail helps with anchoring in high-flow streams, too. It’s a prehensile tail that they can use to grab onto underwater rocks and driftwood for stability. Unfortunately, these lizards will not regrow their tail if it’s lost due to an injury.

Lanthanotus borneensis

The body is rough and textured. Six rows of heavily keeled scales line the body, giving the lizard a somewhat prehistoric look.

The head is broad and lacks any visible hearing mechanism. They don’t have ear openings, tympanic membranes, or any other external ear parts. Surprisingly, these lizards are still capable of hearing even if they lack traditional ears.

Rounding off their facial features are semi-transparent eyelids and small, beady eyes. The eyes are usually light-colored. Pair that with the unique membrane for seeing underwater, and their eyes are quite visible against the rest of the skin.

Don’t be surprised if you hear some subtle vocalizations. These creatures can oscillate the throat to produce a squeaking sound. You might even see a forked tongue flick out of the mouth as they make noise.

For color, earless monitor lizards are pretty plain. Most of the body is dark reddish-brown. Accents of orange-toned brown appear on the lower parts of the body. Meanwhile, the underside is typically mottled, pale yellow, or rust-colored.

Expert Tip: Males and females look fairly similar as far as appearance goes. The most significant difference between the two is the shape of the head and tail. For males, the head and the base of the tail are noticeably broader. Young reptiles are difficult to separate by sex, but those subtle differences become more apparent after the lizard reaches about three years old.


There’s not a ton of concrete information about life expectancy for this semi aquatic lizard species. They’re still new to the trade, so herpetology enthusiasts have a lot to learn.

According to the limited information we have, the average earless monitor lizard lifespan is usually between seven and a half to ten years. Some specimens allegedly surpassed ten years old, but the legitimacy of those reports is still up in the air.

Either way, it’s impossible to guarantee how long an earless monitor lizard will live. The best thing you can do is provide the best care possible and enjoy your time with this unique pet. Staying on top of living conditions and diet gives your earless monitor lizard a good chance of reaching the upper end of the life expectancy range.

Earless Monitor Lizard Size

As a whole, species in this family of lizards can get very large. So it’s not surprising that many people assume that the earless monitor lizard is rather big as well!

Don’t worry, these reptiles are on the smaller end of the size spectrum. The typical earless monitor lizard size is between 12 and 22 centimeters when fully grown. That’s roughly eight inches at most.


Keeping an earless monitor lizard happy and healthy is about creating a conducive environment for its lifestyle and providing a top-notch diet. These monitors are unique compared to most of the other lizards in the pet trade. As a result, earless monitor lizard care requirements can seem a bit unorthodox to the average reptile keeper.

Fortunately, they’re not as challenging to keep healthy as they may seem. Just follow the care guidelines below!

Enclosure Size

The first obstacle you need to overcome is finding a suitable enclosure that fits them. While these lizards might be small compared to other monitors, they still need a considerably large habitat.

That’s because earless monitor lizards are semiaquatic. They spend an equal amount of time living in the water as they do lounging on land. If you want to keep one in captivity, you’ll have to create a habitat that facilitates those needs.

Most earless monitor lizard owners opt for custom-made enclosures. 

The best kind of living space for these reptiles is a habitat with three solid walls. One side of the habitat can have a mesh wall for ventilation.

The solid walls offer excellent insulation and make conditions easier to maintain. You have several options for material. If you want to keep costs low, plywood works fine. However, glass or plexiglass tends to be better for maintenance.

How big should the enclosure be? At the very least, experts recommend dimensions of eight feet long, six feet wide, and three feet long. 

Expert Tip: If you have the room to go bigger, go for it! Earless monitor lizards appreciate the extra space. Some enthusiasts even go so far as to dedicate entire rooms to creating the perfect simulated environment.

What To Put In Their Habitat

Here’s where earless monitor lizard care can get a bit tricky! The key to creating the perfect captive environment for earless monitor lizards is building a swimming space and a land area. How you’ll achieve that depends on the design of the habitat.

For wood-based boxes, you’ll need to use a large container for the water section. Use a sizable tub that’s big enough for the lizard to get in, swim around, and put their entire body underwater.

If you have a watertight enclosure made of glass, you can create a more natural setup with a sloping land area.

For substrate, use a fine particulate that the lizard can easily move with its claws. These guys love to burrow and create makeshift homes in the soil.

The best material you can use is a mixture of clean dirt and soil. Reptile mixes should work well. Avoid anything with large pieces that could pose a choking hazard. Oil-filled mulches are a big no-no, too.

Once you have your water and land sections sorted out, bridge the two areas with a ramp for easy access if necessary. Then, you can start decorating!

For the underwater area, do your best to simulate the rocky rivers these lizards like to inhabit. Add smooth pebbles and rocks at the bottom of the enclosure. A few pieces of driftwood and fake aquatic plants add the finishing touch.

On the dry land, add branches, logs, and other items the lizard would encounter in the wild. Bundles of moss are much-appreciated as well. 

Expert Tip: Feel free to get creative on both the land and water areas. Earless monitor lizards will enjoy every bit of natural decor they can get!

Temperature & Lighting

After you have the perfect habitat, there’s still some work to do. Namely, the lighting and temperature settings need to be stable. 

Install a complete lighting system to recreate natural conditions. These lizards are primarily nocturnal, but that doesn’t mean that solid lighting is unnecessary. They rely on a simulated day and night cycle to keep their circadian rhythm in check.

The lights also serve to heat the enclosure. You can utilize ceramic emitters and even submerged heaters. However, the lights should do the heavy lifting just as the sun would do outside.

Install a thermometer on the land portion of the habitat. You want to aim for temperatures between 75 and 82 degrees Fahrenheit. A few degrees in either direction is acceptable, but try your best to maintain ambient temperatures in the middle of their preferred range.

Expert Tip: Earless monitor lizards adapt well to a wide range of parameters. However, stability is critical for good health. Avoid dramatic fluctuations and sudden temperature drops.

This species will regulate its body temperature by moving between the land and water areas. That said, it’s still a good idea to install a basking lamp in one corner. You don’t have to raise the temperature in that corner to anything extreme.

A few degrees higher than the surrounding ambient air will do just fine.

On top of the standard lighting system, you must incorporate a UV lighting array. UV lamps simulate UVB rays from the sun, which are necessary for calcium synthesis. If you don’t have UV lamps in place, your monitor will suffer the consequences later on.

Use a full-spectrum lamp and position it to shine on the entire enclosure. Like the standard lights, set the lamp on a schedule to provide a day and night cycle.


Humidity isn’t something you need to worry about when it comes to earless monitor lizard care. It’s still an important parameter for their health, but the core design of the habitat takes care of humidity levels for you.

The water section will create all the moist air your lizard needs to stay healthy!


With these monitors spending about half of their lives underwater, conditions there are just as important.

Treat the swimming area as if it were a fish tank. Invest in a powerful filtration system and perform water tests regularly.

Expert Tip: There’s no right or wrong choice for filtration equipment. However, most seasoned owners will tell you that a high-powered canister model is best. Choose a unit that can cycle the water a few times an hour to ensure that ammonia, nitrates, and waste don’t become issues.

Earless monitor lizards prefer an identical temperature range in the water as the ambient air. Use an aquarium thermometer to ensure that the water stays between 75 and 82 degrees Fahrenheit.

Finally, test the pH balance! These lizards do best in neutral waters. Anything too acidic or basic could cause health problems.

Earless Monitor Lizard Food & Diet

Like many other monitor species, the earless monitor is a carnivore. It thrives on high-protein meals. In the wild, these reptiles hunt for fish, insects, and crustaceans.

You can provide much of the same in captivity. Other possible food items include:

  • Squid
  • Crickets
  • Shrimp
  • Tadpoles
  • Pig or chicken liver
  • Baby mice
  • Mussels
  • Mealworms
  • Cockroaches
  • Grasshoppers

Commercial foods are available as well. They’re designed to provide balanced nutrition and fulfill all of the lizard’s dietary needs. It’s also a good idea to invest in supplements. Multivitamins and calcium supplements can do a lot to avoid potential health issues.

Generally, adult earless monitors will need to eat once or twice a week. You may encounter periods where the lizard eats even less frequently. As long as they eventually eat, fluctuations in that schedule are no significant cause for concern.

Earless monitor lizards have a fascinating way of feeding. Instead of consuming the food on dry land, they drag it underwater to eat. They accomplish that unique feat by draining the water from their nostrils as turtles do.

Despite the strange eating habits, avoid tossing food into the water haphazardly. Doing so will only mess up the water conditions and create mold issues.

Use a heavy, tip-proof bowl. Alternatively, you can install an immovable bowl on the side of the enclosure to avoid spillage.

Potential Health Issues

Most of the potential health issues that could affect your earless monitor revolve around their diet. Nutritional deficiencies are common among captive reptiles of any species. The worst offender is calcium.

As mentioned earlier, these lizards need UV light exposure to synthesize calcium properly. Without it, they can suffer from metabolic bone disease. This condition causes abnormal bone growth, general skeletal brittleness, and an increased risk for fractures.

To avoid this issue, make sure that your UV light is working at all times. Switch the bulbs every six months or so to prevent any gaps in UV coverage. Providing calcium supplements can help, too.

Just make sure that you’re not providing too much calcium. Excess calcium can lead to hypercalcemia, which causes kidney stones and issues with the heart and liver. Read the supplement directions closely and only provide the recommended amount.

Beyond dietary problems, earless monitor lizards can suffer from health conditions caused by an unclean environment. 

Like most reptiles, these lizards are prone to bacterial infections, respiratory tract infections, and parasites. Clean the habitat frequently to prevent bacteria and parasites from taking over.

In addition to regular spot cleanings, make sure to disinfect every surface about once a month. While that might seem like a lot of work with an enclosure of this complexity, it’s well worth the peace of mind for your lizard’s health.

Behavior & Temperament

Earless monitors can be a joy to watch. As nocturnal animals, don’t expect to see much activity during the day. That said, occasional daytime observations may occur from time to time.

These lizards venture out of hiding sporadically during the day to move to different areas. 

When they’re awake, the monitors often work on creating burrows. They’ll move the substrate to build small shelters under logs and vegetation. In many cases, they use those makeshift huts for sleeping.

The herpetology community is still learning a lot about earless monitors and how they behave. Generally, it’s not a good idea to keep more than one in the same enclosure. Male and female pairs sometimes cohabitate in peace.

But, males tend to show aggression. They can be territorial, attacking others to claim their space.

Handling Them

Earless monitor lizard care can involve some handling, but these reptiles need to get used to being handled over time.

In the beginning, they’re often shy and suspicious. Give it time, and they will warm up to you and accept short periods of handling.

Usually, these lizards are docile and motionless in your hands. Make sure to support their body weight and avoid any sudden movements, and they should remain peaceful.

As always, pay attention to body language. Males can turn on a dime and try to bite you if they’re uncomfortable. Bites are pretty painful, and recent studies have found that earless monitor lizards do have venom glands! The venom affects blood clotting.

The good news is that the lizard’s venom is pretty weak compared to other monitor species. There hasn’t been much evidence to show that venom causes systemic symptoms in humans. 

Even still, their bites can be painful! Avoid agitating your lizard, and make sure to put them back in the enclosure if they exhibit any signs of aggression.


Earless monitor lizards are fascinating reptiles with a very unique look. On top of that, they’re quite friendly and fun to own!

If you’re considering getting one and have additional questions about their care requirements, don’t hesitate to send them our way. We’re always happy to help our readers whenever we can.