The Argentine black and white tegu (Salvator merianae) is a species of lizard in the family Teiidae. The species is the largest of the “tegu lizards”. This reptile is also called commonly the Argentine giant tegu, the black and white tegu, and the huge tegu.
The specific name, merianae, is in honor of German-born naturalist Maria Sibylla Merian.
In 1839, this species of tegu was originally described as Salvator merianae. However, beginning in 1845 and continuing for 154 years, it was confused with Tupinambis teguixin, and was considered a synonym of that species.
Because subsequent studies had shown that the gold tegu, Tupinambis teguixin, is distinct, in 1995, it was again given species status as Tupinambis merianae
. In 2012, the black and white tegu was reassigned to the resurrected genus Salvator as Salvator merianae.
S. merianae is called the ” black and white tegu” to distinguish it from the “Colombian black and white tegu”, which is another name for the gold tegu. Unscrupulous or incompetent pet dealers sometimes pass off gold tegus as black and white tegus.
- S. merianae and T. teguixin can be distinguished by skin texture and scale count:
- S. merianae has two loreal scales between eye and nostril.
- T. teguixin has only a single loreal scale between eye and nostril.
- S. merianae has round pupils, whereas Tupinambis species have reniform pupils.
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 fill ecological niches similar to those of monitor lizards and are an example of convergent evolution. Yet, this species is invasive here in the State Of Florida. It truly thrives year-round outdoors
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.
Salvator merianae has recently been shown to be one of the few partially warm-blooded lizards, having a temperature up to 18 °Fweinheight higher than the ambient temperature at night time.
However, unlike true endotherms such as mammals and birds, these lizards only display temperature control during their reproductive season from September to December due to possessing seasonal reproductive endothermy.
Because convergent evolution is one of the strongest lines of evidence for the adaptive significance of a trait, the discovery of reproductive endothermy in this lizard complements the long known reproductive endothermy observed in some species of pythons. Yet, supports the hypothesis that the initial selective benefit for endothermy in birds and mammals was reproductive.
As hatchlings, Salvator merianae 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 indicate an older animal.
Adult males are much larger than the females and can reach 3 ft in length at maturity. They may continue to grow to lengths of 4–4.5 ft.
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.
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. In the large adult animals, the posterior teeth are larger and more rounded than the anterior teeth.
Tegu Lizard Diet
Tegus are omnivorous. Juvenile tegus in the wild have been observed to eat a wide range of invertebrates, including insects, spiders, and snails.
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, Tortoise, and even Aquatic Turtle 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, strawberries, and papaya.
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 immobilizes biotin, so excessive feeding of raw eggs may cause fatal biotin deficiency.
Behavior and History
It is a species which inhabits the tropical rain forests, savannas, and semi-deserts of eastern and central South America.
Tegus make amenable pets, as they tend to become attached to their owners, 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.
However, most specimens become more docile as they become larger and less fearful of their owners.
While the teeth can be full of bacteria, 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.
Further interference causes the animal to start lashing its tail, somewhat like a moving snake. In wild animals, a third stage 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.
Housing Tegu Lizards
For adult Argentine tegus, plan on at least a 6-foot by 3-foot by 2-foot enclosure. Unlike other lizards, taller cages are not necessary for tegus as they do not stand on their hind legs or climb trees.
A log or box for hiding should be provided and should be kept slightly damp with wet sphagnum moss, to aid with shedding and as a source of humidity for the animal’s environment. Chances are your tegu will spend most of its time in this hiding spot.
Argentine tegus like to burrow, so they need a substrate that is not only absorbent and easy to clean but also allows their natural digging behavior.
Cypress mulch, orchid bark, or eucalyptus mulch are the preferred substrates for tegus although some people prefer the convenience of several layers of paper for ease of cleaning (although this can stymie the tegus’ natural instinct to dig).
Avoid wood chips, ground corn cobs, or stone gravel due to the risk of ingestion. You should also avoid indoor/outdoor carpeting since it is likely to get shredded in your Argentine tegu’s digging attempts and the stray threads can pose a risk of entangling its nails and toes.
Lighting and Heating
Argentine black and white tegus are diurnal (active during the day), so they need exposure to full spectrum UVA, and UVB lighting like the sun provides. They also need a source of heat.
While it is true that tegus can tolerate cooler temperatures, for proper health and digestion, daytime temperatures should be between 80 and 85 degrees, with a basking spot between 100 and 110 degrees.
Cooler nighttime temperatures are acceptable but don’t allow a drastic change in temperature. Use a combination of reptile heat lamps, bulbs, ceramic heat emitters, and heat mats to reach these high temperatures but avoid hot rocks as they can cause severe burns.
Other Species Of Tegu
- Blue tegu
- Gold tegu
- Teius teyou