• Teius teguixim
  {{small|— Gray, 1845}}
• Tupinambis teguixin
  {{small|— Boulenger, 1885}}
• Tupinambis merianae
  {{small|— Dirksen & De la Riva, 1999}}

The black and white tegu (Salvator merianae), also called the huge tegu,^[1] is the largest species of tegu lizard.^[3] They are an omnivorous species which inhabits the tropical rain forests, savannas, and semi-deserts of east and central South America.

Tegus have unusually high intelligence and can also be house-broken. Like other reptiles, tegus go into brumation (a form of hibernation) in autumn when the temperature drops. They exhibit a high level of activity during their wakeful period of the year.

Tegus fill ecological niches similar to those of monitor lizards, and are an example of convergent evolution.

Etymology

The specific name, merianae, is in honor of German-born naturalist Maria Sibylla Merian.^[4]

Description

As hatchlings, this species has an emerald green color from the tip of its snout to midway down its neck with black markings. The emerald green becomes black several months after shedding. As a young tegu, the tail is banded yellow and black; as it ages, the solid yellow bands nearest the body change to areas of weak speckling. Fewer solid bands indicates an older animal. A tegu can drop a section of its tail as a distraction if attacked. The tail is also used as a weapon to swipe at an aggressor; even a half-hearted swipe can leave a bruise.

Tegus are capable of running at high speeds and can run bipedally for short distances. They often use this method in territorial defense, with the mouth open and front legs held wide to look more threatening.

Adult males are much larger than the females and can reach 3 ft (92 cm) in length at maturity. They may continue to grow to lengths of 4.0–4.5 ft (120–140 cm).

The females are much smaller, but may grow up to 3 ft in length, from nose to tail. They have beaded skin and stripes running down their bodies. Adult females can reach a weight of 2.5 – 7.0 kg.^[5]

The skull is heavily built with a large facial process of the maxilla, a single premaxilla, paired nasals, a single frontal bone, and a single parietal bone. Biomechanical analyses suggest the posterior processes of the parietal might be important for dealing with torsional loads due to posterior biting on one side.^[6] In the large adult animals, the posterior teeth are larger and more rounded than the anterior teeth.^[7]

Warm-bloodedness

Diet

Tegus are omnivorous. Juvenile tegus in the wild have been observed to eat a wide range of invertebrates, including insects, spiders, and snails.^[12] They also eat fruits and seeds. As they grow they become more predatory and the protein content of their diet rises. They may seek out eggs from other reptiles and from birds' nests, and will eat small birds and other vertebrates. In adulthood tegus continue to eat insects and wild fruits, and it is assumed that such components include desirable or essential nutrients.

In captivity, tegus commonly are fed high protein diets that include raw or cooked flesh such as ground turkey, canned & dry dog food, Mazuri Crocodile diet, chicken, eggs, insects, and small rodents. The inclusion of fruit in the diet is recommended. Though some captive tegus do not readily eat fruit, others really enjoy banana, grapes, mango, and papaya.^[13] However, there is evidence that, as in most husbandry of carnivores, it is good practice to cook most of the egg in the diet, so as to denature the protein avidin, that occurs in the albumen. Raw avidin immobilises biotin, so excessive feeding of raw eggs may cause fatal biotin deficiency.^[14]

As household pets

Tegus make amenable pets, as they tend to become attached to their owners {{dubious|date=September 2018}}, and are generally quite docile as adults. They are intelligent and can even be house-broken. A healthy tegu can live for 15 to 20 years in the wild, and possibly even longer in captivity. However, as with most reptiles, if they are not handled regularly, they show more aggressive behaviour; their bite can be painful and damaging due to strong jaws (1000 N bite force, stronger than a dwarf caiman, partly due to the short, deep skull) and sharp incisor teeth in the upper jaw, but most specimens become more docile as they become larger and less fearful of their owners. Tegus do not produce venom.

Tegus do have a threat display if they are upset or stressed. The first stage is huffing, or very heavy breathing, which means be careful {{Citation needed|reason=If not anecdotal, please provide empirical citation for any multi-stage behavioral models of stress responses of Tegus |date=September 2018}}. Further interference causes the animal to start lashing its tail, somewhat like a moving snake. In wild animals, a third stage{{Citation needed|reason=If not anecdotal, please provide empirical citation for any multi-stage behavioral models of stress responses of Tegus |date=September 2018}} of stamping the front feet or "dancing" is seen. If these hints are ignored, then the tegu can charge and may bite, which will require hospital / veterinary attention depending on the victim.{{citation needed|date=June 2018}}