Blue, green, yellow, red, golden, transparent, fluorescent, shiny…the Ocean hides living treasures that would make the peacocks jealous.
What biological chemistry gives fish such varied and changing shades?
Young fish are transparent and their pigmentation appears progressively during their development. The all diversity of fish only holds into a small number of colored pigments: the melanin, the xanthine and the erythrina, respectively black, yellow and red. These pigments are in the specialized cells of the derma and epidermis. Being under nervous or hormonal control, these cells can dilate or contract themselves. By doing so, the pigments can spread or concentrate in a specific area and then change the color of the animal. All these beautiful colors are not only for the show!
Why are coral fish so colorful?
He colors of these fish can have two main but opposite purposes: to blend in or on the contrary to be seen. Colors are a way for animals from the same species, in an environment with a large diversity of animals, to recognize themselves for reproduction or when they need to rest. They are also a way to blend in the decor or to mark its territory. Some tropical fish have strips or spots of contrasted colors, making it difficult for predators to see the shape of the animal. Whether it’s because of its colors or patterns, the look of these animals only serve one purpose: to survive in a small area where many species live together.
The red scorpionfish blends in the rocks due to its camouflage perfected by the pieces of skin floating around its head. Shiny under artificial light, its orange-red color appears to be hard to see in the depths where the only visible color is blue.
This Caribbean fish has a special silvery and golden skin. These colors are not due to pigments such as black, yellow or red. They are the result of the light reflection on cells containing crystals. The inclination of these crystals changes, and then modifies the effect of the light.
This small anemone grows on rocky floors (rocks or wrecks) of the European Atlantic shore. It’s favourite spots are agitated and dark waters. It is therefore near the surface, under rocks or at the entrance of caves that you may see this specie. The Jewell anemones often show bright colors: green, purple, orange, pink… when they are under ultraviolet light, these anemones are highly fluorescent.
The turbot, as all the flat fish, has a great mimetics skill and constantly adapt its colour to the one of the floor. Their eyes observe the colour of the floor and transmit the information through the nervous system to the cells of the skin holding the black, yellow or red pigments. These pigments can spread or on the contrary focus in an almost invisible point, modifying the colour of the animal.
Thanks to their dark shade shell, marine turtles can be easily mistaken with the bottom of the oceans. They are then invisible to their predators. In order to avoid being spotted by their predators living in the bottom of the ocean, the belly of the sea turtles has a light shade.
