The effectiveness of camouflage depends on how predators perceive their environment. Most predatory fish in the Mediterranean have vision adapted to low underwater light and mainly detect contrasts rather than colours.

- Most fish do not perceive all the colours of the visible spectrum as humans do. At depth, for example, red is the first colour to disappear, which explains why many deep-water fish have a reddish tint that makes them virtually invisible.

- Predators such as barracuda or gilthead seabream are particularly sensitive to movement and contrast rather than fine colour detail.

Learn more about fish vision

The limits of fish vision
What are the limits? © dive.explo360.fr — All rights reserved. Reproduction prohibited without permission.

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
Changes in colour, texture and shape are major advantages. © dive.explo360.fr — All rights reserved. Reproduction prohibited without permission.
Chromatophores are specialised pigment-containing cells responsible for the colour of skin, scales and other structures in many animals, including cephalopods (cuttlefish, squid and octopuses), fish, amphibians and reptiles.

Chromatophores contain coloured pigment granules that can be dispersed or concentrated within the cell, changing the visible colour of the skin:

- When pigments disperse, the colour becomes more intense.

- When pigments gather at the centre of the cell, the skin becomes lighter or transparent.

This mechanism is controlled by the nervous system and/or hormones, allowing rapid or gradual colour changes.

Unlike fish chromatophores, those of cephalopods (cuttlefish, squid and octopuses) are expandable pigment sacs controlled by muscles.

1

Melanophores

They allow:

- Pigment dispersion → When melanin granules spread throughout the cell, the skin appears darker.

- Pigment concentration → When the granules gather at the centre of the cell, the skin becomes lighter.

2

Xanthophores

- They contribute to the colourful patterns of many tropical fish, frogs and lizards. In octopuses and cuttlefish, xanthophores can be activated to produce yellowish or orange hues, helping them blend into sandy or rocky environments.

- Combined with other chromatophores (such as melanophores, which produce black and brown, and iridophores, which reflect light to create iridescent effects), they allow complex shades and patterns to form.

3

Erythrophores

They work by absorbing certain wavelengths of light and reflecting red hues.

- Pigment dispersion → The skin appears redder or more orange.

- Pigment concentration → The colour becomes paler or disappears.

4

Leucophores

- Mimic ambient light to blend into the environment. In shallow water, for example, they can reflect sunlight filtered through the water.

- Create complex patterns together with melanophores (pigment dispersion/concentration) and iridophores (which reflect light iridescently).

- Appear white on pale sandy or rocky seabeds, helping conceal the animal.

5

Iridophores

- Create bright, metallic colours such as blue, green, gold or silver depending on the angle of the light.

- Change their appearance dynamically by adjusting the distance between reflective plates, thereby changing the perceived colour.

- Complement the action of melanophores (pigment dispersion/concentration) to produce more complex patterns, improving camouflage or social signalling.

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