Why Do Thorn Devils Have Spikes?

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Thorny devils, with their intriguing appearance and unique characteristics, have always captivated the attention of nature enthusiasts and scientists alike.

These remarkable creatures are known for their distinctive feature – spikes covering their bodies. But what is the purpose of these spikes?

In this blog post, we will explore the fascinating world of thorny devils, shedding light on their nature, the evolutionary adaptations that led to the development of spikes, and how these spikes serve as survival tools in different habitats.

What Are Thorny Devils?

Thorny devils, scientifically known as Moloch horridus, are small reptiles native to the arid regions of Australia. They belong to the lizard family, specifically the agamid family, and are commonly referred to as thorny dragons.

Despite their menacing name, these fascinating creatures are harmless to humans and play an essential role in maintaining the delicate balance of their ecosystem.

Thorny devils are recognized for their intricate appearance, which resembles a miniature dragons adorned with numerous spikes covering their bodies. These spikes, protruding from their skin, give them a striking and intimidating appearance, providing a natural defense mechanism against potential predators.

The Purpose of Spikes on Thorny Devils

The spikes on thorny devils serve multiple important purposes. One of the primary functions is defense against predators. These spikes act as a deterrent, making it difficult for predators to attack or consume them.

When threatened, thorny devils often flatten their bodies, making the spikes more pronounced and creating an even more formidable appearance. This behavior, coupled with their impressive camouflage capabilities, helps them ward off potential threats.

Moreover, the spikes also serve as a means of regulating the thorny devils’ body temperature. Being cold-blooded creatures, they rely on external sources to warm up their bodies. The spikes play a vital role in this process by effectively capturing and retaining solar radiation.

The black coloration of the spikes enables them to absorb a maximum amount of heat from the sun, while the spikes themselves increase the surface area available for absorbing sunlight. This adaptation allows thorny devils to maintain optimal body temperatures for their metabolic processes.

Evolutionary Adaptations of Thorny Devils

The development of spikes on thorny devils is a remarkable example of evolutionary adaptation. Over millions of years, these reptiles have undergone gradual changes to better survive in their harsh and arid environments. Natural selection has favored individuals with traits that enhance their chances of survival, leading to the evolution of spikes as a key adaptation.

One of the primary drivers of the evolution of spikes in thorny devils is the need for effective defense against predators. In the arid regions they inhabit, there is no shortage of potential threats, including birds, snakes, and other reptiles. Thorny devils have evolved a unique defense mechanism to deter predators and increase their chances of survival.

The spikes on thorny devils are not mere appendages but rather modified scales known as “spinose scales.” These scales have undergone specific adaptations to provide protection and increase the lizard’s overall fitness. The spinose scales are composed of keratin, a tough protein that provides rigidity and durability to the spikes.

As predators approach, thorny devils often adopt a defensive posture by flattening their bodies and making their spikes more pronounced. This behavior enhances the visual impact of their spikes, making them appear larger and more intimidating. Potential predators are likely to think twice before attacking such well-defended prey, thus increasing the thorny devils’ chances of survival.

The evolutionary adaptation of spikes in thorny devils has also contributed to their ability to regulate body temperature. Being ectothermic, or cold-blooded, these lizards rely on external sources of heat to raise their body temperature. The spikes play a crucial role in this thermoregulation process.

The black coloration of the spikes enables them to absorb a significant amount of heat from the sun. The spikes also increase the surface area available for absorbing sunlight, allowing thorny devils to maximize their exposure to solar radiation. By positioning themselves strategically to catch the sun’s rays, they can quickly warm their bodies, facilitating essential physiological functions.

Conversely, during hot and scorching days, thorny devils face the risk of overheating. In such situations, the spikes act as a thermal buffer, creating a barrier between their bodies and the scalding sand. This barrier helps dissipate excess heat, preventing the lizards from reaching dangerous body temperatures. The spikes, along with behavioral adaptations like seeking shade, allow thorny devils to maintain a stable internal temperature despite the challenging desert environment.

Another important aspect of the evolutionary adaptation of spikes in thorny devils is their contribution to camouflage and concealment. These lizards are highly adept at blending in with their surroundings, and the spikes play a crucial role in this camouflage strategy.

Thorny devils have the ability to change their coloration, allowing them to match the hues and patterns of the rocks, sand, and vegetation in their environment. The spikes, with their rough texture and earthy coloration, further enhance the lizard’s camouflage abilities. When stationary and in a resting position, the spikes help break up their outline and create a textured surface that mimics the surrounding environment. This remarkable camouflage allows thorny devils to effectively hide from both predators and potential prey, increasing their chances of survival.

The evolution of spikes in thorny devils is a remarkable example of how adaptations can shape the survival strategies of organisms. These spikes serve as a multifunctional tool, providing defense against predators, aiding in thermoregulation, and enhancing camouflage abilities. The evolutionary journey of thorny devils showcases the incredible power of natural selection and adaptation, highlighting the intricate ways in which organisms have evolved to thrive in their unique environments.

Thorny Devils in Different Habitats: Spikes as Survival Tools

Thorny devils are uniquely adapted to survive in various habitats, ranging from deserts to scrublands and sandy plains. Their spikes play a crucial role in ensuring their survival in these challenging environments.

In deserts, where temperatures can soar during the day and drop drastically at night, the thorny devils’ spikes act as a thermal buffer. The spikes help them dissipate excess heat during scorching days by creating a barrier between their bodies and the scalding sand. Conversely, during cold nights, the spikes help insulate the body, reducing heat loss and maintaining a stable internal temperature.

Additionally, the spikes aid thorny devils in camouflage and concealment. These lizards have remarkable color-changing abilities, allowing them to blend seamlessly with their surroundings. The spikes, with their rough texture and earthy coloration, further enhance their camouflage, helping them hide from both predators and prey.


The Thorn Devil, with its impressive spikes, is a testament to the wonders of evolutionary adaptation. These unique reptiles have thrived in the arid regions of Australia by utilizing their spikes as a defense mechanism, a thermoregulatory tool, and even as camouflage. From deserts to woodlands, the spikes on Thorn Devils have proven to be vital for their survival in diverse habitats.

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