Head to head
Tegu vs Monitor Lizard
Tegus and monitor lizards are often compared because they look and behave alike, both being large, active, clever, forked-tongued predators that dig and swim well. They are not related, and the split between the Americas and the rest of the world is the key to telling them apart.
| Tegu | Monitor Lizard | |
|---|---|---|
| Family | Teiidae (with whiptails) | Varanidae |
| Where | South America only, plus invasive in Florida | Africa, Asia, Australasia |
| Size range | Up to about 1.5 m | Under 20 cm to 3 m (Komodo dragon) |
| Diet | True omnivore; lots of fruit and eggs | Mostly carnivore; some large-prey specialists |
| Build | Stocky, shorter neck, bead-like scales | Longer neck, more uniform scales |
| Seasonal warm-bloodedness | Yes in the Argentine tegu | No |
| Forked tongue | Yes, snake-like | Yes, snake-like |
| Famous member | Argentine black and white tegu | Komodo dragon |
Tegu vs Monitor Lizard: common questions
Is a tegu a type of monitor lizard?
No. Tegus and monitors are not closely related and belong to different families that evolved on different sides of the world. Tegus are teiids, a New World family, and their closest relatives are the small, fast whiptail lizards. Monitors are varanids, an Old World family with no American members. The two look and act alike because they independently evolved into the same kind of animal, a large, intelligent, wide-ranging reptile that hunts, scavenges, digs, and swims. This is the same pattern seen between placental and marsupial mammals, where unrelated lineages produce similar forms when they face similar lives.
Which is bigger and more dangerous, a tegu or a monitor?
Monitors, at the top end. The largest tegu, the Argentine black and white, reaches about 1.5 metres and 4 to 7 kilograms and, while it has a strong bite and sharp claws, it is not dangerous to an adult and is usually calm. Monitors span a huge range, and the biggest, the Komodo dragon at up to 3 metres and 70 to 90 kilograms, is a genuine danger to people and can kill an adult, while large water monitors and Nile monitors can also inflict serious bites. Most monitors, though, are medium-sized and no more dangerous than a tegu. Both groups will bite, lash with the tail, and scratch when cornered.
Are tegus and monitors good pets?
Both are kept by experienced keepers and both are demanding. The Argentine black and white tegu is often recommended as one of the best large pet lizards because it is calm, curious, dog-like, and can be handled, though it needs a very large enclosure, strong heat and UVB, a deep substrate for digging, and a varied omnivorous diet, and it lives 15 to 20 years. Monitors vary enormously: the small ackie monitor is a manageable, popular pet, while a savannah monitor is often sold cheap and then outgrows and outlives unprepared owners, and large monitors like the water monitor or Nile monitor need custom rooms and suit very few people. Captive-bred animals are strongly preferred for both.