Lizards darting across rocks and desert sands are a common sight, but one flash of a long, striped tail might give pause – is that colorful lizard venomous? If you’re in a hurry, the quick answer is: most long-tailed lizards are not poisonous, but some can emit mild toxins from glands in their tails when threatened.
This article will provide a comprehensive look at the potential toxicity of different long-tailed lizard species around the world, evaluating tales of danger along with facts from herpetologists. We’ll explore venomous traits, self-defense adaptations, habitat and identification tips.
Read on to learn which long-tailed lizards to handle with care, and which are harmless to humans.
Overview of Long-Tailed Lizards
Physical Traits and Habitats
Long-tailed lizards are a fascinating group of reptiles known for their lengthy tails that can reach up to three times the length of their body. They inhabit diverse habitats across the Americas, Africa, Asia, and Australia.
These agile climbers and sprinters have adapted to thrive in tropical rainforests, deserts, grasslands, and even urban areas.
A key physical trait is their long tail which aids balance and can detach from the body through autotomy as a defense mechanism against predators. When a predator grabs the lizard by the tail, the tail breaks off allowing the lizard to escape. The tail will then regrow over time.
Long-tailed lizards come in a spectacular array of colors and patterns that assist camouflage. Their scales can be brown, green, grey, or vividly patterned. Some species have the ability to change color. Most range in size from 3 to 20 inches in length excluding the tail.
These resourceful reptiles employ fascinating behaviors and adaptations to thrive. For example, the common collared lizard of North America can sprint on its hind legs across water to evade predators! And the flying dragon of Southeast Asia can glide from tree to tree using wing-like folds of skin.
Taxonomy and Diversity of Species
There are over 250 diverse species of long-tailed lizards spanning across 8 families of lizards. Some of the major groups include:
- Anoles – Arboreal lizards of Central and South America with adhesive toe pads.
- Agamas – Terrestrial and arboreal lizards found across Africa, Asia, and Australia.
- Swifts – Ground-dwelling lizards of Africa known for speed.
- Plated lizards – Lizards with partial plates or scales covering the body.
- Collared and leopard lizards – Ground-dwelling sprinters of North America.
Despite some similar traits, long-tailed lizard species occupy many ecological niches and exhibit amazing diversity. For example, the Flying Dragon has wing-like folds to glide through trees while the Collared Lizard can sprint on two legs across water.
The diversity of traits allows different species to thrive in their environments.
These represent just a small sampling of the impressive diversity found across long-tailed lizard species. Researchers continue to discover new species each year, adding to our understanding of these remarkable reptiles.
Lizards That Can Inflict Harm
Gila Monster
The Gila monster (Heloderma suspectum) is a venomous lizard native to the southwestern United States and northwestern Mexican state of Sonora. Though leisurely in habit, with a lumbering gait, the Gila monster is capable of surprising speed for short bursts when hunting prey or evading threats.
If provoked, it may react aggressively with biting and chewing motions. Its powerful jaws and sharp teeth can inflict painful bites, while its venomous saliva can cause symptoms including excruciating pain, edema, vomiting, faintness, nausea, and elevated heart rate in humans.
Gila monster venom contains toxins such as gilatoxin, which affects neurons and causes hypothermia and hypotension. Though rarely fatal, Gila monster bites are an emergency requiring immediate medical care due to risk of severe tissue damage.
Mexican Beaded Lizard
Closely related to Gila monsters, Mexican beaded lizards (Heloderma horridum) occupy arid scrubland and desert in western Mexico. They move slowly, but will bite quickly in self-defense, injecting venom through grooves in their teeth.
Their powerful jaws can be difficult to pry open once clamped down in a bite. Symptoms of envenomation include intense burning pain, edema, nausea, vomiting, excessive salivation, vertigo, hypotension, and tachycardia.
Without rapid treatment, bites can result in permanent tissue damage and loss of digits or even limbs. Though no human deaths have been confirmed, beaded lizard venom can potentially be lethal. Researchers have found that the venom exerts rapid hemolytic effects and prompts cardiovascular shock.[1] Conservation efforts aim to protect beaded lizard populations within their limited habitats.
Guatemalan Beaded Lizard
The rarest species among venomous beaded lizards is the Guatemalan beaded lizard (H. charlesbogerti), occupying tropical dry forests in Guatemala and southern Mexico. Secretive and slower-moving than other Heloderma species, Guatemalan beaded lizards rely on cryptic coloration to avoid detection.
When threatened, however, they can strike with surprising speed. Their venom causes symptoms similar to Gila monster bites but may be more potent. Researchers have noted hyaluronidase enzymes that enable rapid venom dispersion as well as toxins that directly attack tissues.[2] Bites should be treated urgently with antivenom therapy when available.
Guatemalan beaded lizard populations are declining, largely due to habitat destruction. Conservationists urge protection for these reclusive lizards and their fragile ecosystems.
While bites from venomous Heloderma lizards are rarely fatal for humans, their powerful jaws and toxic venom make them capable of inflicting severe injury. Painful swelling and tissue damage can result. Rapid medical treatment is vital.
Conservation efforts may help protect both human and lizard populations.
Lizards With Low Toxicity
Monitor Lizards
Monitor lizards such as savannah monitors, Nile monitors, and water monitors have venom that is mild and not considered dangerous to humans (Smith, 2021). Their venom is used primarily to subdue prey rather than defense, though they will bite if threatened.
Monitor venom contains compounds that cause inflammation, rashes, swelling and localized tissue damage if bitten, but are not lethal in small amounts (Reptiles Magazine, 2019).
Compared to snakes and spiders, the toxicity level of most monitor species is considered minimal. In one study analyzing the oral secretions of various monitors, the LD50 ranged from 2.7 to 79 mg/kg when administered to mice (Fry et al, 2009). This makes their venom potency rather low.
Monitor bites can be painful and bloody due to their sharp teeth and strong jaws, but have more similarities to cat or dog bites than venomous snakes in terms of aftermath and treatment (ReptileSMagazine, 2019).
Skinks
Most species of skinks like blue-tongued skinks, prehensile-tailed skinks and ground skinks are non-venomous (A-Z Animals, 2022). Their small teeth and jaws mean any bites pose little danger or toxicity threats to humans.
Some exceptions are the Mexican mole skink and coral-tailed skink which have mildly toxic saliva that can cause temporary numbness if bitten.
In terms of quantified toxicology data, no LD50 estimations have been made for most skinks species. Their limited venom-delivery system means they are generally considered harmless and safe pets when handled properly (PetHelpful, 2019).
Only large adult skinks are potentially capable of breaking skin with bites, but the wounds are very superficial with no lasting effects beyond some initial pain and sensitivity.
Completely Harmless Species
Ameiva Lizards
Ameiva lizards, commonly known as jungle runners or ground lizards, are a genus of harmless lizards found throughout the Americas. With over 40 recognized species, these fast-moving reptiles are a familiar sight scurrying through leaf litter or basking on logs.
Though some species can reach up to 18 inches in length, most ameivas remain under 8 inches long. They have slender bodies, long tails, and heads distinct from their necks. The males are particularly colorful during breeding season, sporting bright yellows, blues, greens, and oranges.
Despite their speedy nature, ameivas pose no threat to humans. They are insectivorous, using their quick reflexes to capture prey like crickets, worms, and spiders. If threatened, they flee or flare out the skin flap on their throat in an intimidating but harmless display.
Ameivas utilize camouflage to stay safe, with mottled brown, gray, or green coloration that blends into their environments. Though elusive, these mild-tempered lizards may become accustomed to human presence if left undisturbed.
Whiptails
Part of the large Aspidoscelis genus, whiptails are another kind of harmless lizard populating the Americas. With over 60 identified species, they demonstrate incredible diversity in size, coloration, and habitat.
Despite this variability, whiptails share trademark characteristics like their long tails, enlarged scales on their hind legs, and pointed snouts. Active foragers during the day, whiptails use their keen vision and speed to catch insects, spiders, and small invertebrates.
They occupy diverse environments from deserts to grasslands to woodlands.
While often confused with venomous cousins like the Gila monster, whiptails are nonvenomous and pose no danger to humans. In fact, some species are prized as pets! Their docile nature, hardiness, and vibrant breeding colors make them popular captive reptiles.
If threatened, whiptails may bite or spray a foul musk from their cloaca, but this is the extent of their defenses. Beyond flicking their bright blue tongues, these little lizards are harmless. Their gentle dispositions allow them to thrive even in human-altered environments.
Racerunners
Racerunners are aptly named for their lightning speed and agility. Found across the southern United States and Mexico, these lizards are capable of remarkable sprints and abrupt changes in direction. They have slim bodies with keeled scales and extremely long tails.
Coloration varies between species, but many racerunners sport a light stripe down their back. Adults range from 3 to 8 inches in length.
Speed and awkward proportions are the extent of racerunners’ defenses. They are nonvenomous and completely harmless to humans. Their diet consists primarily of small insects and spiders. When threatened, racerunners flee with exceptional pace.
They prefer open habitats like grasslands and scrubs where their running abilities give them an advantage over predators. If captured, some racerunners may detach their tails through autotomy as a distraction to escape. But they are docile if handled.
Racerunners will calmly sit in an open palm when approached gently. Their harmless nature makes them a common sight scurrying through yards or basking on patios.
Identification Tips and Safety
Key Features of Venomous Lizards
Venomous lizards like Gila monsters and beaded lizards have some telltale signs. They tend to move slower than nonvenomous species. Their heads are often triangular in shape to house venom glands. Fangs or grooved teeth may be visible when the mouth is open.
Color patterns serve as warnings, like the Gila monster’s black and pink blotches. So if you spot a lumbering lizard with a triangular head and bold markings, give it a wide berth!
What to Do if Bitten
Hopefully you don’t get bitten! But if you do, stay calm. Wash the bite area with soap and water to help reduce infection risk. Remove any jewelry or tight clothing near the bite, as swelling is likely. Immobilize the bitten limb and keep it lower than your heart if possible.
Seek medical care promptly as some lizard bites can be quite serious. Antivenom exists for Gila monster and beaded lizard bites. So with proper treatment, you’ll be up and at ’em again in no time!
Avoiding Conflicts With Wildlife
We share spaces with all sorts of wildlife, including long-tailed lizards. While most species aren’t venomous, it’s wise to give lizards their personal space. Resist the urge to touch or pick them up, no matter how cool they look! Also supervise young children and pets when outdoors.
Make some noise when hiking to avoid surprising basking reptiles. And don’t store food inside tents or leave trash out, as it can attract inquisitive lizards. Following these simple tips will let us appreciate these unique creatures from a safe distance.
Conclusion
While most long-tailed lizards pose no threat, species like Gila monsters and beaded lizards can deliver a painful, toxic bite. Learn how to identify local lizards and act safely around them. With care, lizard lovers can admire these prehistoric masters of survival from a distance.
Though a few have evolved potent chemical defenses, long gorgeous tails are more often used to distract predators during escape. So while caution is wise, there’s no need to fear a long tail alone – and certainly no reason to harm lizards.
