Are the colorful fish meant to attract natural enemies to eat them?

In daily life, we often see some colorful fish. Facing such beautiful fish, I wonder if you will have such doubts:

Why do fish have such fancy colors? To court a mate? To warn others? It can't be to attract predators to eat it, right? !

Don’t worry, this article will answer these questions for you.

The current situation of the "fish world": You are embarrassed to go out without a flowery dress

The colors of fish are the richest, most colorful and most fascinating in the animal world, and the variety of their colors far exceeds that of insects and birds. When we walk into the fish aquarium, the colorful pictures are dazzling, especially those tropical marine fishes that shuttle through the coral reefs, which are even more dazzling and make people linger.

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It’s quite interesting. Nowadays, as a fish, it’s really embarrassing to go out without nice clothes!

Fish body color and living environment

In the natural environment, most fish have special colors and patterns, or their body color matches the surrounding environment to achieve the purpose of concealing themselves , or to confuse enemies or prey to protect themselves or attack prey .

Fish that live in the upper and middle layers of the ocean, such as mackerel, Spanish mackerel, and tuna, have dark backs, mostly blue-black, dark blue, or dark cyan, and light belly colors, such as silvery white, white, or pale yellowish white. This color is called the annihilation color . If you look down from above, it is difficult to distinguish the fish from the seawater even at a close distance, because the back of the fish is the same color as the seawater under natural light. Looking up from the bottom of the fish, the color of the fish's belly is very similar to the color of the water surface and the sky, making it difficult to distinguish.

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Most freshwater fish have the simple colors mentioned above in order to conceal their bodies. Some species have darker patterns, such as bands, stripes, dots and spots, which are also used for concealment. The body color of some ferocious fish is also for protection or to make use of the concealment of body color so that it is not easy to be discovered by prey .

Fish that live in the middle layer of the ocean, at a depth of 100 to 500 meters, most of them are silver in color, and some species have various red patterns, which is related to the light waves in the water. In the lower layer of the deep sea , at a depth of 500 to 2,000 meters, there is only weak light, or almost no light. Although the back is dark and the belly is lighter like the upper layer fish, the concept of "deep" and "shallow" is different. The fish body is generally brown, black or purple-black , sometimes with silver on the scales, but they rarely have spots, stripes and bright colors. Most of them are dark in color, which is consistent with the surrounding environment.

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Fish that live along the coast and in the shallow seabed are found in almost all colors, from simple and plain gray or brown to the most brilliant colors and patterns. Usually, when the spots, bands and patterns are present, the fish's body is similar to the color of the bottom, rocks or water plants. Fish that live among granite can show various granite-like shades; fish that live among lava are mostly black; fish that live among seaweed are mostly green; fish that live among Sargassum are olive green; and fish that live among red coral reefs are mostly red. Fish that often lie flat on the seabed and hide in the mud and sand have yellow-brown backs, which blend into the mud and sand and are difficult to distinguish.

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The most colorful fish live in the coral reefs of tropical oceans . Although coral reef fish have a variety of dark patterns, the purpose of these patterns is nothing more than to blur the outline of the fish body , thereby hiding the shape of the body . Some butterfly fish have black bands on their heads, the edges of which are often white or blue, and there is a large dot similar to an eye on the back of the body, which is sometimes edged with white or yellow. When this fish moves, it often moves its tail first and swims slowly backwards for a short distance. When frightened, it moves its head first and swims forward in the opposite direction at a very high speed. The patterns of this fish often cause potential enemies to mistake the tail end for the head, so that when the butterfly fish encounters an enemy, it can move in the opposite direction of the enemy's expectation, and as a result successfully escape the attack.

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Moreover, some fish of the same species may have different colors due to different living environments . For example, the colors of sea trout in British rivers are clearly related to the surrounding environment. Trout living in rapid rivers and small water bodies in high mountains have many round spots on their bodies; while those living in large lakes become bright silver-white, and the round spots become X-shaped black spots; trout living in muddy ponds or lakes with muddy bottoms are darker in color; but those living in caves and crevices are almost completely black; and those living in gravel-bottomed lakes have beautiful colors, more beautiful shapes, and are more lively.

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Conclusion:

Almost all fish have certain colors, some are single-colored, while others are richly colored and form various stripes and spots. Biocolor has many biological significances. Common biocolor phenomena include cryptic color (protective color), warning color, eye spots, mimicry, sexual color , etc. These are the products of fish's long-term adaptation to the environment and are of great significance to the survival and reproduction of fish. The beautiful "colorful clothes" are not just for show!

Produced by: Science Popularization China

Author: Life Pulse Team

Producer: China Science Expo

Submitted by: Computer Information Network Center, Chinese Academy of Sciences

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