Photo credit: Mgoodyear
Human beings are often fascinated by what is different from them. If some are skilled and know how to use the art of makeup to transform a face or even the art of disguise to allow a male actor to transform into a woman, our transformation capabilities remain limited. Also the chameleon is an animal that arouses great curiosity. After explaining how it is capable of changing color quickly, we will discuss the few animals capable of fairly similar feats.
How and why does the chameleon change color?
The chameleon’s color change mechanism relies on a combination of biological and physiological factors. The skin of these animals has specialized pigment cells called chromatophores and iridophores. Chromatophores contain color pigments. We distinguish between melanophores (loaded with black pigment, melanin), erythrophores (loaded with red carotenoid pigments) and xanthophores (loaded with yellow pigments, also carotenoids). Iridophores contain reflective crystals filled with microcrystals of guanine and adenine that allow chameleons to change the wavelength of the light they reflect, hence producing a wide range of vibrant colors from blue red or orange.
Chameleon skin also has sensory receptors sensitive to light or temperature. They send the collected information to the chameleon’s central nervous system. The chameleon’s brain processes the data and, if necessary, commands the chromatophores to change color. Motor neurons control the muscles surrounding the chromatophores, allowing these pigment cells to contract or expand.
Chameleons use this color-changing mechanism primarily for camouflage, but also to communicate with other chameleons and regulate body temperature. Color change can occur in less than 30 seconds.
Octopuses, squid and cuttlefish are also capable of changing color quickly. Their chromatophores and the pigments they contain are also controlled by their central nervous system. In cephalopods, the same mechanism as that described in the chameleon exists, but more advanced, since cephalopods can modify the shape of cells themselves. This allows them to change color in a flash.
Squid and cuttlefish flash bands of pigment to let people know they are ready to mate. The Humboldt squid can make the chromatophores of its entire body flicker at once, going from pale red to dark red sometimes up to four times per second.
Note that the prize undoubtedly goes to the Mimetic Octopus or Mime Octopus (Thaumoctopus mimicus), discovered in 1998, the only species of octopus that can take the form of other marine animals. It lives in the warm waters of Southeast Asia. Not only does it change color, but it also adapts its shape. It is capable of imitating around fifteen different species including sea snakes, lionfish, willows, frogfish, giant crabs, rays, mantis shrimp, jellyfish and certain shellfish such as sea anemones. Wed. She is also capable of pretending to be dead to better attack her prey by surprise.
Charidotella sexpunctata is a Central American ladybug with a transparent shell containing a superposition of very thin plates with tiny grooves. She can fill these grooves with a red fluid which gives them a smooth, mirror-like appearance. This gives the animal a golden metallic look. But if the ladybug is disturbed or if it mates, the fluid escapes, causing the mirror effect to cease and the underlying bright red pigmentation to reappear.
Amphibian skin also contains chromatophores and iridophores. In these animals, we differentiate color changes. It may be an individual variation of colors in the same species or a normal temporary color change in the same individual. Only the second type of change comes close to the chameleon phenomenon.
It is observed in the green tree frog (Hyla arborea) is a frog that measures between 3.5 and 5 cm. Its back is apple green but can vary from light green to brown. It also has long fingers with suction cups on each paw. Its eyes are yellow-orange in color and have a horizontal pupil.
If the green tree frog is kept in a yellow bucket, it turns very pale yellow. If kept on tree bark, it turns dark brown in less than an hour, and will return to its green color in a few minutes if put back on green foliage. The color change can also result from the physiological state of the animal. Air humidity and temperature can also influence its appearance.
Other species of amphibians may exhibit similar phenomena, but to a lesser degree.
The green anole (Anolis carolinensis) is a small lizard native to the Southeastern United States. It is also found in Mexico, the Bahamas, the Cayman Islands and Hawaii. A male can reach a maximum length of 22 centimeters and a female, 16 cm. They weigh approximately 4g. They have a slender body, crowned with a triangular head.
It sports bright green colors but is nicknamed “American chameleon” because of its ability to change its color. It can turn gray-brown to camouflage itself among tree trunks and in the shadows. Its belly, however, always remains white. When it feels threatened, it also turns brown, while exhibiting lethargic behavior. Black circles may also appear.