Limits of marine predators’ vision
An animal’s visibility depends on light, distance and the viewer’s visual system. Matching the background may reduce contrast; irregular patterns can make outlines harder to follow. Predators do not all see the same colours, so camouflage effective against one may be less effective against another.
ACTIVE CAMOUFLAGE
Active camouflage allows some animals to change their appearance in moments to adapt to their surroundings. Colours, patterns and sometimes even skin texture transform to blur their outline and deceive the eye. In cephalopods, this spectacular ability becomes a powerful tool for defence, hunting and communication.
Chromatophores
In cuttlefish and octopuses, muscles expand or relax small pigment sacs called chromatophores. The visible coloured area changes rapidly under nervous control.
In many fish, colour change instead involves pigment granules moving within cells. These two mechanisms should not be confused.
Melanophores
In the fish concerned, melanin granules spreading through melanophores darken the skin; aggregation can lighten it.
Xanthophores
Xanthophores contain yellow pigments. This category described in vertebrates should not be directly applied to the muscular mechanism of cuttlefish and octopuses.
Erythrophores
Erythrophores contain red or orange pigments. Their contribution depends on the species and the organisation of its skin.
Leucophores
Leucophores scatter light and can produce whitish areas. This is an optical effect, not a universal white pigment.
Iridophores
Iridophores contain reflecting structures that produce iridescence. Depending on the species, these structures may be more or less adjustable.
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