Tegu Talk 101

Of all the lizards in the world, few are as fascinating as tegus. They rank among the largest and most intelligent of lizards, and possess a suite of adaptations that at times make them seem more mammalian than reptilian. A staple of the pet trade and the bane of conservationists, there is far more to tegus than meets the eye.

The Argentine black and white tegu Sept  images

Tegu Natural History

Tegus are large, omnivorous lizards found throughout the rainforests and savannahs South America. There are very few countries without at least one species and their range extended as far north as Panama. All tegu displays display elaborate patterns of broken spots and stripes that act as disruptive coloration to break up the animal’s outline. When not out foraging for food, they like to spend time in burrows; smaller species are known to nest in termite mounds. Although primarily terrestrial, tegus are excellent swimmers and can hold their breath for nearly half an hour. They belong to the Teiidae family along with ameivas, jungle-runners, whiptail lizards, and caiman lizards. Despite bearing a strong superficial resemblance to the monitors of the genus Varanus, tegus are not related. They are more terrestrial, have shorter necks, and are capable of autotomizing their tails. True tegus are divided between the genera Tupinambis—containing the Colombian/gold tegu (T. teguixin), the Rhondonia tegu (T. longilineus), the swamp tegu (T. palustris) and the four-lined tegu (T. quadrilineatus)—and Salvator, which contains the Argentine tegu (S. merianae), red tegu (S. rufecens), and the yellow tegu (S. duseni). Several species are known to hybridize in captivity. Recent genetic work has split the Colombian tegu is four distinct species. Salvator tegus are known to hibernate for up to seven months of the year whereas the more tropical Tupinmabis tegus do not, although some may brumate in captivity during the cooler months.

Goldteju Tupinambis teguixin  df bTupinambis rufescens

Description

Tegus are large lizards, ranging from three to over four-and-a-half feet in length depending on species, a good portion of which is tail. Generally, Tupinambis tegus max out at around three-and-a-half feet and five to eight pounds and have a sleek, streamlined appearance. They have pointed, narrow faces that make them look like a cross between a small monitor and a skink. Salvator tegus are more heavily built, with broader, blunter snouts and seemingly stumpier legs. They can achieve weights of 15 to over 20 pounds and lengths in excess of four feet, with some larger males reaching close to five feet and over 30 pounds. Another difference between the genera is the number of loreal scales between the eyes and nostrils; Tupinambis has one while Salvator has two. Tegus exhibit strong sexual dimorphism, with males being markedly larger than females, having a pair of raised, bump-like scales on either side of the cloaca, and sporting hyper-developed jaw musculature known as “jowls.” These are a sexually selected trait, with bigger, more fit males displaying bigger jowls. Males also make a popping noise with them to impress potential mates. It was recently discovered that during the breeding season, male Argentine tegus can maintain their core body temperature up to 10 degrees warmer than their surroundings, effectively making them the world’s only warm-blooded reptile; the mechanisms by which they generate this heat are still currently being studied.

Unknown  Unknown Bandwtegu

Diet

As a result of their huge jaw muscles, tegus possess the strongest bite of any lizard and are capable of generating bite forces of 1000 N. Unlike most reptiles, tegus have differentiated teeth much like a mammal. The teeth in the front of the jaw a pointed and incisiform, several bladelike caniniform are on the sides for seizing prey, and the teeth in the back are blunt and molariform for crushing. This unique dentition coupled with their incredible bite force allows tegus to take a wide variety of food items and they are actually highly specialized for omnivory. In many ways, they are the reptilian equivalent of bears. Tegus will eat just about anything that will fit in their mouths and are known to prey on other reptiles, small mammals, ground-dwelling birds, invertebrates of all kinds, fallen fruit, fish, smaller members of their own species, and carrion. One of their favorite foods is eggs and they are notorious as nest raiders of both wild and domestic fowl. They are even known to beg tourists for handouts and scavenge out of dumpsters. Some research suggests that tegus may be important in helping to disperse the seeds of the plants they consume.

Unknown  Gold tegu torun

Tegus and Humans

Throughout their native range, tegus are harvested for their exquisitely patterned, beaded hides. Tegu leather is highly prized for its use in a number of products, including handbags, purses, boots, belts, and weapon sheathes. Many people in South America consume tegus, as well. In the rest of the world, tegus are valued as pets. Part of the appeal is their impressive size, but they are also known for their personality. Unlike many other reptiles, they will interact with their keepers and even actively seek out affection much like a dog or cat. Due to their high intelligence, tegus are very curious and excellent at solving problems. Many can be taught to recognize their name, come on command, and even be potty-trained! With proper care, pet tegus can live more than 15 years.

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Tegus as Invasive Species

A recent surge in popularity has caused a tegu boom in the US and as a result, some have escaped captivity and become established as invasives. Florida makes for wonderful tegu habitat. Like the South American rainforest it is hot and humid, but lacks predators to control their numbers and has an abundance of prey animals that have no natural defense to tegu predation. Of particular concern is the tegu’s egg-eating habits. The Everglades is the northernmost point of the American crocodile’s range and serves as nesting sites for countless species of wading birds and sea turtles. Tegus have been caught on camera systematically raiding alligator nests, taking only an egg or two  day until the entire nest is consumed. As both a dietary and habitat generalist, they directly compete with and displace native species.

The Argentine black and white tegu Sept

 

For info on other lizards of South America, check out our Reptile Center!

For info on invasive species in Florida, check out our Conservation Center!

For info on for tegus’ fruit-eating habits help seed dispersal, check out our Botany Center!