Reptiles With Hair: The Strange But True Phenomenon

The idea of a scaly reptile covered in hair seems like something out of a sci-fi movie. However, some reptiles do in fact have hair, challenging our assumptions about this group of animals. If you’re short on time, here’s a quick answer to your question: A small number of reptile species, including geckos and chameleons, have modified scales called ‘setae’ that resemble mammalian hair. In this detailed guide, we’ll explore the science behind reptilian ‘hair’, look at some real-world examples, and unpack why this strange phenomenon exists.

We’ll cover everything you need to know about reptiles with hair. First, we’ll examine how and why some lizards and chameleons evolved hair-like scales. Next, we’ll profile 5 reptile species known to have distinct hair or hair-like coverings.

We’ll look at their evolutionary history and habitat as well as close-up photos of their unique appearances. Finally, we’ll discuss some theories about the purpose and function behind reptile hair. Whether you’re a reptile enthusiast or just curious about these exceptional animals, you’ll come away with a deeper understanding of this surprising phenomenon.

The Science Behind Reptile ‘Hair’

While mammals are well known for growing lush coats of hair, some reptiles also sprout unusual strands that resemble fuzzy pelts. However, the ‘hair’ found on certain lizards, snakes, and dinosaurs evolved independently from mammalian fur and has a very different structure and purpose.

Modified Scales Called Setae

Reptilian ‘hair’ consists of slender, keratin-based filaments called setae that are actually modified scales. Setae emerge from follicles in the skin, giving the appearance of fine, soft fur. However, under a microscope, the individual strands have a smooth, translucent quality unlike the complex structure of mammalian hair.

Differences From Mammalian Hair

In addition to the simpler microscopic structure, reptile setae lack the complex follicle and erector muscle that allow mammalian fur to lift and change position. Setae are relatively stiff keratin spikes anchored deeply in the skin, though they have a velvety texture when stroked. The setae of mammals serve entirely different purposes than hair.

While hair provides insulation, setae likely serve decorative or sensory roles. For example, horned lizards have setae around their eyes that may protect them from dust or sand. Other lizards use setae to enhance cryptic coloration for camouflage.

Interestingly, some dinosaur fossils reveal evidence of setae-like structures.

Evolutionary Origins and Advantages

Researchers theorize setae evolved through separate lineages in various lizard and snake species. Growing keratin spikes from the skin likely helped reptiles blend into their environments and sense predators or prey.

Over time, this conferred survival advantages that allowed setae mutations to persist.

Today, setae add to the exotic appearances of bearded dragons, chameleons, and rat snakes. While reptile ‘hair’ serves different functions than fur, it remains an intriguing example of evolutionary innovation. With ongoing study, scientists continue uncovering new insights into setae origins and properties.

Reptile Species With Hair and Hair-Like Coverings

Madagascar Girdled Lizard

The Madagascar girdled lizard is a medium-sized lizard native to Madagascar with some very unique features. Most notably, some individuals have hair-like spinose scales that project along the midline of their back and tail (Bauer et al. 2006).

These spinose hairs likely play a role in defense against predators. The Madagascar girdled lizard occupies a variety of habitats across Madagascar.

Bearded Pygmy Chameleon

The aptly named bearded pygmy chameleon has hair-like projections along the lower jaw that resemble a beard. Native to parts of east Africa, these tiny reptiles grow to around 2 inches in length. The function of the “beard” is not definitively known, but it likely plays a role in regulating moisture levels or defense (Tolley & Herrel 2014).

Pygmy chameleons as a group are poorly studied and some species may have hair-like filaments over other parts of the body.

Bartlett’s Pygmy Chameleon

Another African pygmy chameleon, Bartlett’s pygmy chameleon has fine hair-like structures along the sides of the body. Reaching just 1.6 inches in length, not much is known about this lizard’s natural history.

The function of the hair-like filaments is unknown but likely assists in moisture regulation or camouflage (Loveridge 1967). More study is needed of this species and its obscure reptilian relatives.

Satanic Leaf-Tailed Gecko

One of the more distinct-looking lizards is the Satanic leaf-tailed gecko, which is named for the pointy projections along its body resembling leaves. Native to parts of Madagascar, these geckos have incredible camouflage abilities.

The numerous skin flaps and projections enable them to resemble dead leaves on the forest floor. The “hairs” likely assist primarily in disguise from predators but may also gather moisture (Brygoo 1971). Unfortunately the gecko’s restricted habitat makes it vulnerable to extinction.

Madagascar Ground Gecko

Lastly, the Madagascar ground gecko is a small terrestrial gecko with hair-like spines above each eye. Reaching just over 3 inches in length, this species has only been recently described by scientists (Glaw et al. 2012).

The function of the unusual “eyebrow” hairs is unclear but probably assists in camouflage like many Madagascar lizards that resemble plant parts. Much remains unknown about this small, secretive reptile.

Theories on the Purpose and Function of Reptile Hair

Camouflage and Mimicry

Some scientists theorize that the hair found on certain reptiles serves a camouflage purpose. The hair may help the reptiles blend into their surroundings and avoid detection by predators or prey. For example, the hair on thorny devils resembles the small twigs and debris often found in their habitat.

This close resemblance likely helps conceal thorny devils very effectively as they move slowly through the desert.

In other cases, the hair may enable mimicry, allowing reptiles to resemble the appearances or movements of other species in their environment. Several lizard species closely mimic snakes in appearance, possibly to deter potential predators.

The hair or elongated scales on some lizards could make them appear more snakelike in form and movement.

Communication and Sensory Perception

Some researchers propose that the hair functions to enhance communication, social interaction, or sensory capabilities for certain reptiles. For example, bearded dragons have hair around their throats that may allow them to sense subtle vibrations and engage in complex communication. The throat hair could act like specialized whiskers that detect slight air currents or vibrations when other bearded dragons make noises or movements nearby.

This would enable more nuanced social signaling.

Temperature Regulation and UV Protection

Given that reptiles rely on external heat sources to regulate their body temperature, some scientists believe reptile hair plays a thermoregulatory role. The hair may assist with soaking up heat from the sun or retaining metabolic body heat.

One study on bearded dragons found their throat hair helped regulate temperature and buffer changes in external temperatures compared to areas without hair.

In addition, melanin and other pigments in reptile hair may filter out harmful ultraviolet radiation from the sun, protecting sensitive skin underneath. Several lizard species seem to have more prominent hair along their dorsal areas, possibly to reduce UV exposure along their backs and heads when basking.

Preventing Water Loss

Some researchers hypothesize that reptile hair helps reduce water loss, especially for desert-dwelling species. Hair along the reptile’s back may disrupt air currents flowing over the skin surface, slowing the evaporation of moisture. Studies comparing desert reptiles with varying amounts of dorsal hair found that increased hair correlated with lower overall water loss rates.

Table 1 shows the results below:

Conclusion

While extremely rare in the reptile world, certain lizard and chameleon species have evolved hair-like projections from their scales, challenging the notion that reptiles must be bald and scaly. As we’ve explored, these bizarre filaments likely serve key purposes from camouflage to temperature regulation.

Looking ahead, continued research and genetic analysis may reveal new insights into how and why reptile hair evolved.

The existence of furry reptiles expands our understanding of adaptation and biology. Next time you come across an image of a hairy gecko, don’t be too surprised – just appreciate the diversity and wonder of evolution!