Chameleons are remarkable lizards that are well-known for their incredible ability to change color. This color changing ability allows chameleons to communicate, regulate body temperature and blend into their surroundings as a defense mechanism against predators.
How do chameleons change color?
Chameleons can change color through specialized pigment cells called chromatophores that lie underneath their transparent outer skin layer. There are several different types of chromatophores that each contain a different color pigment:
- Melanophores contain black and brown melanin
- Xanthophores contain yellow and orange pigments
- Iridophores contain reflective plates that create blue, green and gold colors
- Erythrophores contain red pigment
By dispersing or concentrating the pigment within these chromatophore cells, chameleons can rapidly change the visible color of their skin. Dispersing the pigment expands the cell, exposing a larger area of color, while concentrating the pigment contracts the cell, revealing less color.
For example, when a chameleon is calm, the melanin in its melanophores is usually contracted, so little black pigment can be seen. However, when the chameleon gets angry or stressed, the melanophores rapidly disperse their melanin, which makes the skin appear much darker.
How do chameleons know what color to turn?
Chameleons change color through both physiological color change and rapid active color change.
Physiological color change happens more slowly, over hours or days, and is passively controlled by factors like temperature, mood and health. For example, colder temperatures can trigger a chameleon’s melanophores to contract, causing the skin to appear lighter. Stress and anger can cause melanin to disperse, darkening the skin.
Active color change relies on specialized cells called iridophores that reflect specific wavelengths of light. By adjusting the spacing between the plates of reflective material inside iridophores, chameleons can rapidly change reflected color in just seconds or minutes. This allows them to actively camouflage by matching nearby colors.
To change color so precisely, chameleons rely heavily on their excellent eyesight. Each eye can move independently, allowing chameleons to see nearly 360 degrees. Special photoreceptor cones in their eyes allow them to see colors in the visible light spectrum as well as UV light.
This allows chameleons to see color contrasts and patterns all around them. Their brains then process this visual information and send signals to the chromatophores to adjust their pigment accordingly and match the environment.
Why do chameleons change colors?
The main functions of color change in chameleons include:
- Camouflage – Chameleons can change to match their surroundings as a defense against predators. The more their color and pattern blends in, the less visible they are.
- Communication – Bright and vivid displays are used to attract mates, warn off rivals and signal territorial dominance.
- Temperature regulation – Darker colors can help absorb heat, while lighter colors reflect heat.
- Mood – Color changes can signify anger, fear, stress or other emotions.
Camouflage is likely the primary evolutionary reason behind a chameleon’s color changing ability. By being able to closely match the specific environment they are in, chameleons can avoid detection from predators like birds, snakes and larger lizards.
Some chameleons like the panther chameleon also use bright colors as a communication display during mating. Males in particular use vivid stripes and patterns to attract females and outcompete rival males.
By changing to darker black, brown and green colors, chameleons can better absorb heat from sunlight. Lighter colors like yellow, green and turquoise help reflect excess heat. This helps chameleons maintain an optimal temperature as conditions change.
Since physiological color change is influenced by mood, the colors displayed by a chameleon can also provide social cues to other chameleons. Dark grays and blacks tend to indicate anger or fear, while brighter greens and yellows signal a calm, relaxed mood.
What limits chameleons color changing abilities?
While chameleons have impressive color changing abilities, there are some limitations:
- Speed – Color changes for camouflage take seconds, but physiological shifts are slower.
- Contrast – Colors and patterns must already be present in the environment.
- Lighting – Chameleons see less color distinction in low light.
- Temperature – Cool temperatures limit color change.
- Energy – Frequent changes can be energetically draining.
Rapid active camouflage is limited by how fast the chameleon’s cells can disperse or concentrate pigments, which takes a few seconds at minimum. Very slow color changes over hours or days are also possible.
Chameleons are limited in what colors and patterns they can display by what is already naturally present in the environment. They cannot create colors and markings, only match what they see.
Since chameleons rely on visual cues for color change, their abilities are much more limited in low light conditions where color distinction is reduced. They often appear more washed out at night or under heavy forest canopy.
Cold temperatures inhibit the chemical reactions needed for significant color change. So in cold conditions, chameleons are constrained to paler shades of grays, greens and blues.
Frequently changing colors requires a lot of cellular activity and energy expenditure. Chameleons may not be able to sustain rapid color changes for long periods of time.
Unique color changing abilities in chameleons
Among reptiles, the chameleon really stands out for its remarkable color changing talents. Here are some of the things that make chameleon color change unique:
- Rapid speed – Color shifts in seconds to minutes for camouflage.
- Wider spectrum – Can see UV light in addition to the visible spectrum.
- Combined morphs – Pattern changes complement color changes.
- Social functions – Bright colors used for mating and territorial displays.
- Temperature – Coloration used to regulate temperature.
Very few reptiles can fine-tune their coloration as quickly as the chameleon. Even closely related lizards like anoles and geckos pale in comparison to a chameleon’s defenses.
By detecting UV light, chameleons have an expanded range of color perception that allows them to match environments more precisely. Very few mammals can see into the UV spectrum.
Chameleons don’t just shift uniform colors, their patterning also changes in congruence through spots, stripes and blotches. This provides a better visual match to surroundings.
Many lizards have some limited ability to use color for social signaling and mating. But chameleons take it to another level with vivid, dynamic displays.
While many reptiles do use coloration to control body temperature, the chameleon’s temperature regulation through color change is exceptionally effective.
Do other animals change color like chameleons?
Chameleons have the most extensive and specialized color changing abilities in the animal kingdom. However, there are some other creatures that use color change to blend into environments or for social signaling, including:
| Animal | Color Change Abilities |
|---|---|
| Octopus | Rapid changes to skin color, pattern and texture for camouflage |
| Cuttlefish | Swift color and pattern alterations for camouflage and signaling |
| Prawns | Transparent bodies that take on color of surroundings |
| Squid | Chromatophores allow moderate color shifts for camouflage |
| Crab spiders | Some species can change to match flower colors |
| Arctic fox | Molts brown summer coat and grows white winter fur |
Cephalopods like octopus, squid and cuttlefish have excellent camouflage abilities through color change thanks to specialized pigment cells called chromatophores. But cephalopod color shifts rely more on patterns over a limited color range.
Transparent prawns excel at taking on the exact color of their environment through refractive processes rather than pigment cells. Crab spiders have more limited color change abilities based on their last molt.
Arctic foxes and other animals like ermines, snowshoe hares and rock ptarmigans can change color seasonally through molting and growing new fur or feathers. But this process is very slow compared to chameleons.
Conclusion
Chameleons possess color changing talents that far exceed any other animal on Earth. Using specialized cells called chromatophores containing pigments, they can rapidly shift colors and patterns to disappear into their surroundings for camouflage or stand out for social display.
While cold temperatures, lighting conditions or energy use can limit chameleon color change, they still have unmatched skills. The chameleon’s exceptional eyesight detects subtle visual cues that allow it to actively change to just the right color and pattern within seconds.
These remarkable lizards rely on their color changing capabilities to evade predators, regulate temperature, communicate and express moods. Their distinctive ability has made chameleons a prime example of camouflage and visual signaling in the animal kingdom.
