Lizards are a group of animals that have more than 5,000 identified species throughout the world. They are considered successful because of 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 live in or near urban areas and, precisely because they are close to humans, there is often concern about which ones may be dangerous to 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 equipped with dental structures to directly inoculate the poison, it can enter the victim's bloodstream along with saliva once the teeth have caused a bite. Given the above, in this article on our site, we want to talk to you about the types of poisonous lizards that exist. As you will see, the majority of poisonous lizards belong to the genus Heloderma and Varanus
Mexican Scorpion (Heloderma horridum)
The Mexican scorpion (Heloderma horridum) is a species of lizard that is threatened due to the pressures its population receives from indiscriminate hunting, given its poisonous nature, but also because of the illegal trade because both medicinal and aphrodisiac properties are attributed to it and, in many cases, it ends up having as a pet.
It is characterized by measuring about 40 cm, being robust, with a large head and body, but a short tail. The coloration varies on the body, being between light to dark brown with combinations between black and yellow. 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 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 can include pink, yellow or white markings on black or brown scales.
It is carnivorous, feeding on rodents, small birds, snakes, insects, frogs and eggs, among others. It is a protected species, as it is also in a state of vulnerability.
Beaded lizard or scorpion (Heloderma charlesbogerti)
The beaded lizard, scorpion or Guatemalan (Heloderma charlesbogerti) is typical of Guatemala, inhabiting dry forests. Its population is strongly impacted by habitat destruction and illegal trade in the species, which makes it critically endangered
It feeds mainly on eggs and insects, having arboreal habits. The coloration of the body is black with irregular yellow spots.
Komodo Dragon (Varanus komodoensis)
The dreaded Komodo dragon is endemic to Indonesia and 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 the saliva that ended up for causing sepsis in the dam. However, subsequent studies have shown that these are capable of producing poison, which has important effects on the 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 for it to collapse before proceeding to tear it apart and eat it.
The Komodo dragon is included in the red list of threatened species, so protection strategies have been established.
For more information on Komodo dragon venom, you can read this other article on Is the Komodo dragon dangerous to humans?
Savannah monitor lizard (Varanus exanthematicus)
Another of the poisonous lizards is the Savannah Monitor Lizard (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. It can measure up to about 1.5 meters and its head is wide, with a narrow neck and tail.
It is originally from Africa, however, it has been introduced in Mexico and the United States. It feeds mainly on spiders, insects, scorpions, but also on small vertebrates.
Goanna (Varanus varius)
Goanna (Varanus varius) is an arboreal species endemic to Australia. It inhabits dense forests, within which it can cover large areas. It is large, measuring up to a little over 2 meters and weighing approximately 20 kg.
On the other hand, they are carnivores and scavengers. As for its coloration, it is between dark gray and black, and may have black and cream-colored spots on its body.
Mitchell's Water Monitor (Varanus mitchelli)
The Mitchell Water Monitor (Varanus mitchelli) inhabits Australia, specifically in swamps, rivers, lagoons and inbodies of water in general. It also has the ability to be arboreal, but always in trees associated with bodies of water.
Has a varied diet, including aquatic and terrestrial animals, birds, small mammals, eggs, invertebrates, and fish.
Varanus Argus or yellow-spotted Varanus (Varanus panoptes)
Among the most poisonous lizards, the Argus or yellow-spotted varanus (Varanus panoptes) also stands out. It is found in Australia and New Guinea and females measure up to about 90 cm, while males can reach 140 cm.
They are distributed in various types of terrestrial habitats and also near bodies of water, and are excellent burrowers. Their diet is very varied and includes various small vertebrates and invertebrates.
Spiny-tailed Monitor Lizard (Varanus acanthurus)
The Spiny-tailed Monitor Lizard (Varanus acanthurus) owes its name to the presence of spiny structures on its tail, which it uses in his defense. It is small in size and lives mainly in arid areas, being a good digger.
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 forests 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 about 40 cm, are nocturnal and carnivorous, feeding on crustaceans, fish and earthworms.
This species was not always known to be poisonous, however, it has recently been possible to identify glands that produce toxic substances, which have an anticoagulant effect, although not as powerful as that of other lizards. Bites from this species are not fatal to people
The poison of lizards of the genus Heloderma
The bite of these animals is quite painful and when it is caused in he althy people, they can recover. However, sometimes could be deadly, causing significant symptoms in the victim, such as, asphyxiation, paralysis and hypothermia, so cases must be de alt with promptly. These lizards of the genus Heloderma do not directly inoculate the poison, but when they tear the victim's skin, they secrete the toxic substance from specialized glands and it 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, as is the case of gilatide (isolated from the Gila monster) and exenatide, which seem to be surprisingbenefits in diseases such as Alzheimer's and type 2 diabetes , respectively.
The poison 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 VaranusThese have poisonous glands in each jaw, which flow into specialized channels between each pair of teeth.
The venom produced by these animals is an enzymatic cocktail, similar to that of some snakes and, as in the Heloderma group, they cannot directly inoculate the victim, but when they bite the toxic substance it penetrates into the blood together with the saliva, causing coagulation problems, so it generates spills, in addition to hypotension and shock that ends with the collapse of the person who has suffered the bite. The classes of toxins identified in the venom of these animals are cysteine-rich proteins, kallikrein, natriuretic peptide, and phospholipase A2.
A clear difference between the genus Heloderma and Varanus is that in the former the poison is transported through dental canaliculi, while in the latter the substance is excreted from the interdental areas.
Some accidents involving people with these animals have ended fatally, as the victims end up bleeding to death. 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 because they are considered poisonous. However, this turns out to be a false belief that often 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 mistakenly considered to be poisonous:
- Alligator lizard, snake lizard or scorpion lizard (Gerrhonotus liocephalus).
- Alicante mountain lizard (Barisia imbricata).
- Little snapdragons (Abronia taeniata and Abronia graminea).
- False chameleon (Phrynosoma orbiculare).
- Oak forest skink (Plestiodon lynxe).
A common trait in poisonous lizard species is that most are in some state of vulnerability, leading them to be in danger of extinction. The fact 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.