What is a Chromatophore?
A chromatophore are specialized cells which can contain or produce pigment, or reflect light in a specific way to create a certain desired hue. They are found in cold blooded animals like fish, amphibians, reptiles, crustaceans, and cephalopods, along with certain bacteria. Chromatophores serve a number of functions; in addition to coloring the skin and eyes of these animals, the cells can also help to protect the animals from predators or radiation, and they are used to signal other creatures. Scientists also use chromatophores to study various aspects of animal life; the cells have been identified and studied since the early 1800s.
Some biologists break chromatophores up into two rough categories: biochromes and schemochromes. Biochromes actually contain and produce pigment, while schemochromes can change the way that light reflects from the skin of the animal, thereby changing its color. Biologists may also classify a chromatophore by the colors that it produces; cyanophores, for example, produce colors in the blue range. Iridescent animal coloring is produced by iridophores.
In addition to simply creating flat color, many chromatophores can also be used to help an animal change color. This trait is often observed in animals like octopi, lizards, and some fish. The cells can accomplish a color change by expanding or contracting each individual chromatophore to cover varying areas of the animal's skin, in response to stimuli like light. In addition to making excellent camouflage, these color changing cells can also help an animal regulate its body temperature, or they can signal information to other animals of the same species.
People who have observed the rapid color change of animals like octopi have probably noticed that the color change spreads like a blush, rather than happening all at once. This appears to be caused by a sequential firing order for neurons in the brain as they respond to a changing environment. Creatures like octopi with a highly refined chromatophore control system can mimic the color and texture of their environment remarkably well; this camouflage technique is used to hide from predators and also to pursue unsuspecting prey.
Photosynthetic bacteria also use chromatophores, to help them produce energy. The pigments in bacteria may take the form of bacteriochlorophyll, and they are capable of photosynthesis. Different bacteria may use and arrange their chromatophores in different ways, depending on how they evolved and where they live. Depending on the bacteria, the colors a chromatophore takes can range from rich brown to bright green.
Discussion Comments
Mimicry is a defense against predators wherein the animal copies the appearance of a predator.
@hamje32 - I remember that whole tree octopus fiasco. Frankly, I don’t think that the professor proved his point at all.
Unless you’re a trained biologist, how are you supposed to know if the thing is a fake? Maybe all of evolution is fake then? These things are only exposed as hoaxes after the fact, usually by people who are trained specialists in the subject matter and can spot the fraud a mile away.
I don’t think it’s fair to expect students to figure this out alone, considering that there is so much weird and strange variety among biological specimens that it’s not unreasonable to think that anything so crazy as a tree octopus shouldn’t be possible.
@miriam98 - I don’t doubt those facts are true at all, just don’t believe everything you watch on television or read on the Internet.
I am not referring to the chameleon, but an Internet hoax called the tree octopus that was concocted in the late 1990s. I guess a professor was trying to prove to students that they were gullible, and he directed them to this website that appealed to saving the endangered tree octopus.
This was an octopus, as its name would suggest, that grew on trees. The images were photo shopped and the thing was later exposed to be a hoax.
How did I get off on this? Oh yeah, the tree octopus, as was explained on the fake website, also supposedly had the ability to change skin color: it turns red when angry and white when afraid. All other times it just blends in with the background.
I think it’s fascinating that animals can change their skin color to adapt to a variety of conditions. I’ve known about one famous example, the chameleon, for most of my life. I used to think that chameleons changed color to camouflage themselves. However, I watched a National Geographic special once which indicated that this is not the primary reason.
They mainly change color to shelter themselves from both too much cold and too much light. Different colors absorb and reflect light and heat differently to accommodate these changes in the environment.
They may also change colors to send a signal to other animals that they’re ready to fight, if provoked. In these situations their skin turns red (just like humans do when they’re mad I suppose).
I also found that they change colors when they’re going through mood changes! I guess they’re like mood rings, in this regard.
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