Answer: Well, the octopus is like a chameleon because it can change the color of its skin to match the sand.Because octopuses are invertebrates, meaning they don't have backbones, they can squeeze themselves into small spaces between the rocks to get out of reach of their predators
From what I could find, chameleons and octopuses use very similar mechanisms for colour change. But when it comes to camouflage, octopuses can go a bit further.
Under the initial pigment-free skin layer there are additional layers of cells called chromatophores which are separated into different sub-groups of cells which contain different colour changing methods. In the case of xanthophores, erythrophores, melanophores and cyanophores, the cells contain sacs (called vesicles) of pigment (depending on the type; cyanophores hold blue pigments, melanophores brown or black, for example) which give the cell colour when the sac expands. The other subtypes are the iridophores, which use crystalline plates comprised of guanine to defract light, causing bright colours (though the exact colour is determined by the plate angels), and the leucophores which use similar purine-based plates to reduce light-scatter and produce whiter hues.
It was for a long time commonly thought that chameleons changed their colours through the use of a combination of layered pigment and crystal cells (as stipulated here: Science Questions), however research has shown that chameleons heavily utilise their iridophore layers and have fewer pigment-types than previously thought.
They change colour rapidly by modulating the excitation of the guanine nanocrystal structures in their iridophore layers, in conjunction with their pigments. (see here: Photonic crystals cause active colour change in chameleons)
I couldn't find references to octopuses using the same mechanism, they seem to largely rely on pigments more than their iridophore structures.
Answers & Comments
Answer: Well, the octopus is like a chameleon because it can change the color of its skin to match the sand.Because octopuses are invertebrates, meaning they don't have backbones, they can squeeze themselves into small spaces between the rocks to get out of reach of their predators
Answer:
From what I could find, chameleons and octopuses use very similar mechanisms for colour change. But when it comes to camouflage, octopuses can go a bit further.
Under the initial pigment-free skin layer there are additional layers of cells called chromatophores which are separated into different sub-groups of cells which contain different colour changing methods. In the case of xanthophores, erythrophores, melanophores and cyanophores, the cells contain sacs (called vesicles) of pigment (depending on the type; cyanophores hold blue pigments, melanophores brown or black, for example) which give the cell colour when the sac expands. The other subtypes are the iridophores, which use crystalline plates comprised of guanine to defract light, causing bright colours (though the exact colour is determined by the plate angels), and the leucophores which use similar purine-based plates to reduce light-scatter and produce whiter hues.
It was for a long time commonly thought that chameleons changed their colours through the use of a combination of layered pigment and crystal cells (as stipulated here: Science Questions), however research has shown that chameleons heavily utilise their iridophore layers and have fewer pigment-types than previously thought.
They change colour rapidly by modulating the excitation of the guanine nanocrystal structures in their iridophore layers, in conjunction with their pigments. (see here: Photonic crystals cause active colour change in chameleons)
I couldn't find references to octopuses using the same mechanism, they seem to largely rely on pigments more than their iridophore structures.
Explanation:
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