Poisonous lizards - Types and photos

Lizards are a group of animals that have more than 5,000 species identified all over the world. They are considered successful for their diversity, but also because they have managed to occupy almost all ecosystems globally. It is a group with internal variations in terms of morphology, reproduction, feeding and behavior. Many species are found in wild areas, while others inhabit urban places or near these and, precisely because they are close to humans, there is often concern about which ones may be dangerous for people.

For a time it was thought that the species of lizards or lizards that were poisonous were very limited, however, recent studies have shown many more species than originally believed capable of producing toxic chemicals. Although most are not actually trained with dental structures to directly inoculate the venom, it can enter the victim's bloodstream along with saliva once the teeth have caused a bite. Given the above, in this AnimalWised article, we want to talk to you about the types poisonous lizards that exist. As you will see, most poisonous lizards belong to the genus Heloderma and Varanus.

You may also be interested in: Types of lizards Index
  1. Mexican scorpion (Heloderma horridum)
  2. Gila Monster (Heloderma suspectum)
  3. Beaded lizard or scorpion (Heloderma charlesbogerti)
  4. Komodo Dragon (Varanus komodoensis)
  5. Savanna monitor (Varanus exanthematicus)
  6. Goanna (Varanus varius)
  7. Mitchell water monitor (Varanus mitchelli)
  8. Varanus Argus or yellow-spotted (Varanus panoptes)
  9. Spiny-tailed monitor (Varanus acanthurus)
  10. Earless lizard (Lanthanotus borneensis)
  11. The venom of lizards of the genus Heloderma
  12. The venom of lizards of the genus Varanus
  13. Lizards mistakenly considered poisonous

Mexican scorpion (Heloderma horridum)

The Mexican scorpion (Heloderma horridum) is a species of lizard that is threatened due to the pressures that its population receives from indiscriminate hunting, given its poisonous nature, but also by the illegal commerce because both medicinal and aphrodisiac properties are attributed to it and, in many cases, it ends up having as a companion animal.

It is characterized by measuring about 40 cm, being robust, with a large head and body, but a short tail. The coloration varies in the body, being between light brown to dark with combinations between black and yellow. It's found mainly in Mexico, along the Pacific coast.

Gila Monster (Heloderma suspectum)

The Gila monster or Heloderma suspectum inhabits arid spaces in northern Mexico and the southern United States. It measures about 60 cm, having a fairly heavy body, which limits its movements, so it tends to move slowly. Its legs are short, although it has strong claws. Its coloration may include pink, yellow or white markings, on black or brown scales.

It is a carnivore, feeding on rodents, small birds, snakes, insects, frogs, and eggs, among others. It is a protected species, as it is also found in state of vulnerability.

Beaded lizard or scorpion (Heloderma charlesbogerti)

The chaquirado, scorpion or Guatemalan lizard (Heloderma charlesbogerti) is own from Guatemala, inhabiting dry forests. Its population is strongly impacted by the destruction of the habitat and by the illegal trade of the species, which makes it be in critical danger of extinction.

It feeds mainly on eggs and insects, bearing arboreal habits. The color of the body is black with yellow irregular spots.

Komodo Dragon (Varanus komodoensis)

The dreaded Komodo dragon is endemic to Indonesia and it can measure up to 3 meters in length and weigh about 70 kg. For a long time it was thought that this, one of the largest lizards in the world, was not poisonous, but due to a mixture of pathogenic bacteria that inhabit its saliva, when biting its victim, it impregnated the wound with saliva that ended for causing sepsis in the prey. However, subsequent studies have shown that these do are capable of producing poison, which has important effects on victims.

These animals are active hunters of live prey, although they can also feed on carrion. Once they bite the prey, they wait for the effects of the poison to act and it collapses before proceeding to tear and eat it..

The Komodo dragon is included in the red list of Endangered Species, therefore, protection strategies have been established.

For more information on the venom of the Komodo dragon, you can read this other article on ¿The Komodo dragon is dangerous to humans?

Savanna monitor (Varanus exanthematicus)

Another poisonous lizard is the Savannah Monitor (Varanus exanthematicus). It has a thick body, as well as its skin, for which it is attributed immunity to the bites of other poisonous animals. Can measure up to about 1.5 meters and its head is broad, with a narrow neck and tail.

It is native to Africa, however, it has been introduced in Mexico and the United States. It feeds mainly on spiders, insects, scorpions, but also small vertebrates.

Goanna (Varanus varius)

Goanna (Varanus varius) is an arboreal species endemic to Australia. It inhabits dense forests, within which it can travel large areas. It is large in size, measuring up to a little over 2 meters and weighing approximately 20 kg.

On the other hand, they are carnivores and scavengers. Regarding its coloration, it is between dark gray and black, and may have black and cream-colored spots on its body..

Mitchell water monitor (Varanus mitchelli)

Mitchell's water monitor (Varanus mitchelli) lives in Australia, specifically in swamps, rivers, lagoons and in water bodies usually. It also has the ability to be arboreal, but always in trees associated with bodies of water..

Has a varied diet, which includes aquatic or terrestrial animals, birds, small mammals, eggs, invertebrates and fish.

Varanus Argus or yellow-spotted (Varanus panoptes)

Among the most poisonous lizards, the Argus or yellow-spotted varanus (Varanus panoptes) also stands out. Is found in Australia and New Guinea and the females measure up to about 90 cm, while the males can reach 140 cm.

They are distributed by various types of terrestrial habitats and also near bodies of water, and are excellent excavators. Its diet is very varied and includes diverse and small vertebrates and invertebrates.

Spiny-tailed monitor (Varanus acanthurus)

The spiny-tailed monitor (Varanus acanthurus) owes its name to the presence of spiny structures on its tail, which he uses in his defense. It is small in size and lives mainly in arid areas, being a good excavator.

Its coloration is reddish brown, with the presence of yellow spots. Their diet is based on insects and small mammals.

Earless lizard (Lanthanotus borneensis)

The Earless Lizard (Lanthanotus borneensis) is endemic to some areas of Asia, inhabiting tropical rainforests near rivers or bodies of water. Although they lack certain external structures for hearing, they do manage to hear, and they are also capable of emitting certain sounds. They measure up to 40 cm, are nocturnal and carnivorous, feeding on crustaceans, fish and worms.

It was not always known that this species was poisonous, however, recently it was possible to identify glands that produce toxic substances, which have a anticoagulant effect, although not as powerful as that of other lizards. The bites of this species they are not lethal to people.

The venom of lizards of the genus Heloderma

The bite of these animals is quite painful And when it is caused in healthy people, they can recover. However, sometimes could be deadly, as they cause significant symptoms in the victim, such as, suffocation, paralysis, and hypothermia, so cases must be dealt with promptly. These lizards of the genus Heloderma do not directly inoculate the venom, but when they tear the skin of the victim, they secrete the toxic substance from the specialized glands and this flows to the wound, entering the body of the prey.

This poison is a cocktail of various chemical compounds, such as enzymes (hyaluronidase and phospholipase A2), hormones and proteins (serotonin, helothermin, gilatoxin, helodermatin, exenatide and gilatide, among others).

Some of these compounds contained in the venom of these animals have been studied, such as gilatida (isolated from the Gila monster) and exenatide, which seem to present surprising benefits in diseases such as Alzheimer's and type 2 diabetes, respectively.

The venom of lizards of the genus Varanus

For a time it was thought that only lizards belonging to the genus Heloderma were poisonous, however, later studies showed that toxicity is also present in the genus Varanus. These have poisonous glands in each jaw, which flow through specialized channels between each pair of teeth..

The poison these animals produce is a enzyme cocktail, similar to that of some snakes and, as in the Heloderma group, they cannot inoculate it directly to the victim, but when biting it the toxic substance penetrates into the blood along with saliva, causing clotting problems, thus generating strokes, plus hypotension and shock which ends with the collapse of the one who has suffered the bite. The classes of toxins identified in the venom of these animals are proteins rich in cysteine, kallikrein, natriuretic peptide and phospholipase A2..

A clear difference between the genus Heloderma and Varanus is that in the former the venom is transported through dental canaliculi, while in the latter the substance is excreted from the interdental areas.

Some accidents of people with these animals have ended in a fatal way, since the victims end up bleeding. On the other hand, those who are treated quickly manage to save themselves.

Lizards mistakenly considered poisonous

Commonly, in various regions some myths are generated about these animals, specifically regarding their danger as they are considered poisonous. However, this turns out to be a false belief that many times ends up harming the population group due to indiscriminate hunting, especially with the lizards that appear at home. Let's look at some examples of lizards and lizards that are considered mistakenly poisonous:

  • Alligator lizard, snake lizard or scorpion lizard (Gerrhonotus liocephalus).
  • Alicante mountain lizard (Barisia imbricata).
  • Little dragons (Abronia taeniata Y Abronia graminea).
  • False chameleon (Phrynosoma orbiculare).
  • Oak forest skink (Plestiodon lynxe).

A common trait in poisonous lizard species is that most are found somewhere state of vulnerability, leading them to be in danger of extinction. That an animal can be dangerous does not give us the right to annihilate it, regardless of the consequences it brings to the species. In this sense, all forms of life on the planet must be valued and respected in their proper dimension..

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