Chromatophores
Chromatophores are cells that contain pigment found in amphibians, fish,reptiles, crustaceans, cephalopods, and bacteria. In cold blooded mammals they are responsible for eye colour and skin. They are developed in the neural crest during embryonic development and mature chromatophores are grouped according to colour. - xanthophores-yellow - erythrophores-red - iridophores-reflective/iridescent - leucophores-white - melanophores-black/brown - cyanophores-blue |
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Cephalopods
Cephalopods like octopus’s control their chromatophres using their muscles while vertebrates like chameleons use cell signaling using hormones or neurotransmitters as signals. In cephalopods each chromatophore unit is composed of a single chromatophore cell and many muscle, nerve, glial and sheath cells. In the chromatophore cells, are pigment granules that are enclosed in a sack called a cytoelastic sacculus. To change their colour an octopus uses its muscles to change the shape of the sack , therefore changing the translucency, reflectivity, or opacity of the cell. An octopus can operate chromatophores in complex wave like displays that result in a variety of colour schemes. The nerves that operate chromatophores are positioned in the brain in a pattern like the chromatophores they control so the pattern of colour change matches pattern of neuronal activation. Some octopus’s can not only match the colour of their background but also the texture. |