Mexican Beaded Lizard vs Gila Monster: What are the Differences?

Slowest Animals In North America
Vaclav Sebek/

Written by Emmanuel Kingsley

Published: June 5, 2022

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Did you know that there are about 5,000 different species of lizards in the world? One can find these incredible reptiles in Africa, Asia, Central America, Eurasia, Europe, North America, Oceania, and South America. Like some other reptiles, many lizards love cuddling and will have a good time resting in your hands. Interestingly, one can keep caiman, green iguanas, savannah monitors, Chinese water dragons, chameleons, green basilisk, black and white tegus, skinks, geckos, and bearded dragon lizards as pets.

However, many lizards are venomous even if they don’t secrete toxins potent enough to kill humans. The Mexican beaded lizards and Gila monsters are some of the most fearsome venomous lizards with similar characteristics. However, you’ll learn to tell their difference below.

Comparing Gila Monsters and Mexican Beaded Lizards

Mexican beaded lizards differ from Gila monsters in size and combat behavior.
Gila MonstersMexican Beaded Lizards
Size It can grow up to 22 inches long. It’s the largest lizard in the USACan grow as long as 35 inches.
Habitat Deserts and dry places of Southern Nevada and California’s San Bernardino CountyDry forests
Combat behavior Body twistsHigh arch posture
Feeding Three large meals Larger variety 
ReproductionApril to June September and October 
Conservation statusNear threatenedLeast concern
Coloration Black with traces of orange, pink, or yellowDarker shades

Key Differences Between Mexican Beaded Lizard Vs. Gila Monster

As the only species in the Helodermatidae family, Mexican beaded lizards and Gila monsters have so much in common. However, we’ve noticed some differences in both reptiles. The most remarkable distinguishing characteristics are their size, habitat, and combat behaviors.

First, the Mexican beaded lizard can grow bigger than the Gila monster, with longer tails. Meanwhile, Gila monsters are the largest lizards in the United States of America. The second most striking difference between both reptiles is their habitat. One will likely find Gila monsters in deserts and Mexican beaded lizards in dry forests.

Furthermore, Gila monsters twist their bodies in combat, while Mexican beaded lizards maintain a high arch posture. Other differences between Mexican bearded monsters and Gila monsters lie in their reproduction, feeding, conservation status, and reproduction. We’ll study all these extensively as we proceed.

Mexican Beaded Lizard Vs. Gila Monster: Size 

The Mexican beaded lizard is larger than the Gila monster, growing up to 35 inches long.

Mexican beaded lizards and Gila monsters share similar physical features. For example, they both have bead-like scales and a large, scout frame. So, telling them apart from merely looking at them is quite challenging. However, Gila monsters are shorter than Mexican beaded lizards, growing 22 inches long. Mexican beaded lizards can grow up to almost 35 inches long and they’re also much heavier than Gila monsters. Again, Mexican beaded lizards have longer tails than Gila monsters. While Gila monsters’ tails are about half their body length, Mexican beaded monsters have tails two-thirds the length of their bodies.

Mexican Beaded Lizard Vs. Gila Monster: Habitat

The Gila monster is native to Southwestern United States and the northwestern Sonora in Mexico, and they’re commonly found in Arizona, Nevada, and Utah. Gila monsters live in deserts and dry places of southern Nevada and California’s San Bernardino County. One isn’t likely to find them in open grasslands, as they avoid open areas.

Meanwhile, as its name suggests, the Mexican bearded lizard is native to Mexico and southern Guatemala. They live in dry forests (especially pine-oak forests) and woodlands, but you can also find them in deserts.

Mexican Beaded Lizard Vs. Gila Monster: Combat Behavior

Both reptiles exhibit interesting male-to-male combat behaviors in the breeding season. First, it’s noteworthy to learn that male Mexican beaded lizards and Gila monsters fight to prove high endurance and physical strength. The winner is more likely to find a female to mate with than the other lizards. Combats can last up to three hours. While both reptiles have similar combat behaviors to many monitor lizards, there are also striking differences in positioning. During combat, Mexican beaded lizards go for a high arch posture while pressing their bellies together. Meanwhile, male Gila monsters will twist their bodies in a wrestling bout.

Mexican Beaded Lizard Vs. Gila Monster: Feeding 

Mexican beaded lizards and Gila monsters are foragers as they search far and wide for food. They typically feast on young rodents, frogs, snakes, earthworms, lizard eggs, and dead meat (carrion). Sometimes, they go as far as climbing trees to feed on bird eggs.

Gila monsters’ large size enables them to eat about one-third of their weight in a meal. In addition, they can meet their energy requirements for the year with just three heavy meals. 

However, Mexican beaded lizards typically eat more variety of food than Gila monsters. They also need to search for food more frequently than Gila monsters do to meet their dietary requirements. 

Mexican Beaded Lizard Vs. Gila Monster: Reproduction

Gila monsters and Mexican beaded lizards are pretty different in reproductive biology. Mexican beaded lizards have mature spermatozoa around September. They court and mate in September and October and lay eggs between October and December, with hatchlings emerging around June and July.

On the other hand, spermiogenesis, courtship, and mating happen between late April and early June for Gila monsters. Gila monsters lay their eggs in July and August, and one will notice their hatchlings appearing the following April. While Gila monsters can lay as many as twelve eggs in a clutch, Mexican beaded lizards can lay 22 eggs in a clutch.

Mexican Beaded Lizard Vs. Gila Monster: Conservation Status 

Gila monsters are considered near threatened by the IUCN Red List.

The International Union for Conservation of Nature (IUCN) categorized Mexican beaded lizards and Gila monsters as least concern.

The Convention on International Trade in Endangered Species of Wild Fauna and Flora (CITES) lists reptiles as Appendix II species. This means that they are protected species and are safe from collection and killing. However, the International Union for Conservation of Nature has classified Gila monsters as near threatened species.

Mexican Beaded Lizard Vs. Gila Monster: Coloration

Mexican beaded lizards and Gila monsters are black with orange, pink, or yellow traces. However, one may find that the Mexican beaded lizards have blacker coloration than Gila monsters.

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