''Salvator'' is a
genus
Genus ( plural genera ) is a taxonomic rank used in the biological classification of living and fossil organisms as well as viruses. In the hierarchy of biological classification, genus comes above species and below family. In binomial nom ...
of
lizards known as
tegu
Tegu is a common name of a number of species of lizards that belong to the families Teiidae and Gymnophthalmidae. Tegus are native to Central and South America. They occupy a variety of habitats and are known for their large size and predator ...
s which belong to the
family
Family (from la, familia) is a group of people related either by consanguinity (by recognized birth) or affinity (by marriage or other relationship). The purpose of the family is to maintain the well-being of its members and of society. Idea ...
Teiidae
Teiidae is a family of autarchoglossan lizards native to the Americas. Members of this family are generally known as whiptails or racerunners; however, tegus also belong to this family. Teiidae is sister to the Gymnopthalmidae, and both famili ...
.
Description
Tegus are large reptiles, with some species reaching a total length of around , and a weight of approximately . These opportunistic, wide-ranging lizards can be found in a variety of habitats, from
swamps to
rain forests
Rainforests are characterized by a closed and continuous tree canopy, moisture-dependent vegetation, the presence of epiphytes and lianas and the absence of wildfire. Rainforest can be classified as tropical rainforest or temperate rainforest, ...
to
savanna
A savanna or savannah is a mixed woodland- grassland (i.e. grassy woodland) ecosystem characterised by the trees being sufficiently widely spaced so that the canopy does not close. The open canopy allows sufficient light to reach the ground to ...
s and cities. Although terrestrial, they are capable swimmers, able to remain submerged for up to 22 minutes and having even been caught in gill nets set at sea.
Biomechanical studies have shown that tegus have stronger limb bones than comparably-sized mammals or birds, a trait that may be inherent to amphibians and reptiles. They exhibit social and maternal behaviour; female tegus construct burrows to lay their eggs in, and will protect their brood until they hatch. Up to 35 eggs are produced in a clutch. Tegus will hibernate together in groups, though males exhibit territorial behavior towards each other. Tegus exhibit
sexual dimorphism
Sexual dimorphism is the condition where the sexes of the same animal and/or plant species exhibit different morphological characteristics, particularly characteristics not directly involved in reproduction. The condition occurs in most an ...
. Males display greatly expanded and prominent "jowls" along the base of the lower jaw. These jowls are the result of extensive growth of the ventral pterygoideus muscles (a prominent jaw closing muscle in reptiles).
[Rieppel, O. 1980. The Trigeminal Jaw Adductor Musculature of ''Tupinambis'', with Comments on the Phylogenetic Relationships of the Teiidae (Reptilia, Lacertilia). Zool. J. Linne. Soc. Vol. 69(1):1–29.][McBrayer, L.D., White, T.D. 2002. Bite Force, Behavior, and Electromyography in the Teiid Lizard, ''Tupinambis teguixin''. Copeia. No. 1:111–119.] Though both sexes exhibit
hypertrophy
Hypertrophy is the increase in the volume of an organ or tissue due to the enlargement of its component cells. It is distinguished from hyperplasia, in which the cells remain approximately the same size but increase in number.Updated by Linda J. ...
of the ventral pterygoideus muscle, likely in response to their
durophagous
Durophagy is the eating behavior of animals that consume hard-shelled or exoskeleton bearing organisms, such as corals, shelled mollusks, or crabs. It is mostly used to describe fish, but is also used when describing reptiles, including fossil tu ...
habits,
[Pianka, E.R., Vitt, L.J. 2003. Lizards: Windows to the Evolution of Diversity. California. U. Cal. Press.] male tegus show both greater relative and absolute muscle mass compared to females.
Further evidence for sexual selection of these jowls comes from observations that ventral pterygoideus muscle mass increases in males during the reproductive season.
Metabolic changes also occur during the reproductive season, in which the body temperature is increased up to 10 degrees Celsius and sustained internally like a bird or a mammal. This discovery has major evolutionary implications, providing support for the hypothesis that
endotherm
An endotherm (from Greek ἔνδον ''endon'' "within" and θέρμη ''thermē'' "heat") is an organism that maintains its body at a metabolically favorable temperature, largely by the use of heat released by its internal bodily functions inst ...
y may have evolved in response to parental care.
Ecology
Tegus are
omnivorous
An omnivore () is an animal that has the ability to eat and survive on both plant and animal matter. Obtaining energy and nutrients from plant and animal matter, omnivores digest carbohydrates, protein, fat, and fiber, and metabolize the nut ...
, foraging for a wide range of foods using their forked tongues, including fruit, fungi, various arthropods, small vertebrates, carrion, and eggs. The amount of meat that is consumed by tegus decreases as the animals mature.
As adults, tegus have few predators. Among them are big cats, birds of prey and large snakes. Tegus defend themselves using their powerful jaws, which can exert forces of up to 1000N. A bite from an adult tegu can crush human fingers.
Though more terrestrial (
morphologically less well-adapted for climbing into tree canopies or for swimming), tegus fill an ecological niche in South America similar to that filled by
monitor lizards in Africa, Asia and Australia, and are an example of
convergent evolution
Convergent evolution is the independent evolution of similar features in species of different periods or epochs in time. Convergent evolution creates analogous structures that have similar form or function but were not present in the last com ...
. Though similar in appearance to monitors, tegus are not closely related and can be distinguished by their larger heads, shorter necks, heavier bodies and different arrangement of the scales on the body and tail. Monitors have laterally compressed tails, well-suited for aquatic propulsion, while tegus' tails are more cylindrical or even broader than high. In addition, tegus are
facultative biped
A facultative biped is an animal that is capable of walking or running on two legs (bipedal), as a response to exceptional circumstances (facultative), while normally walking or running on four limbs or more. In contrast, obligate bipedalism is w ...
s while monitors are obligate quadrupeds.
Economic importance and environmental impact
Tegus are among the most commercially exploited reptiles in the world. Up to 1,000,000 are harvested annually in their native Argentina for their hide and meat, and are particularly important as a source of income in rural or indigenous communities. Tegus can also be found in captivity, where they are bred for the pet trade. They are reported to be highly intelligent, becoming docile as they mature and in some cases even ignoring food in favor of social interaction. However, tegus have demanding
husbandry
Animal husbandry is the branch of agriculture concerned with animals that are raised for meat, fibre, milk, or other products. It includes day-to-day care, selective breeding, and the raising of livestock. Husbandry has a long history, startin ...
requirements due to their large size.
Within their native range, tegus are often thought of as pests, sometimes raiding chicken coops to feed on the eggs or fowl. They are noted predators of ground nesting bird and
crocodilian eggs, and in some areas 80% of
spectacled caiman nests are destroyed by tegus. In Florida, they have become an
invasive species, and prey on the eggs of
American alligator
The American alligator (''Alligator mississippiensis''), sometimes referred to colloquially as a gator or common alligator, is a large crocodilian reptile native to the Southeastern United States. It is one of the two extant species in the gen ...
s instead. Predation by feral tegus may pose a threat to Florida's endangered wildlife, such as the
Key Largo woodrat
The Key Largo woodrat (''Neotoma floridana smalli''), a subspecies of the eastern woodrat (''Neotoma floridana''), is a medium-sized rat found on less than 2,000 acres (~8.09 square kilometers) of the northern area of Key Largo, Florida, in the ...
and the
American crocodile
The American crocodile (''Crocodylus acutus'') is a species of crocodilian found in the Neotropics. It is the most widespread of the four extant species of crocodiles from the Americas, with populations present from South Florida and the coasts ...
. Due to their fruit eating habits, tegus may serve an important ecological function by
dispersing seeds through their droppings.
Classification
Listed alphabetically.
''Salvator''
The Reptile Database
References
{{Taxonbar, from=Q11846621
Lizard genera
Taxa named by André Marie Constant Duméril
Taxa named by Gabriel Bibron