Animal color

  Animals can reduce damage from other animals by hiding. Therefore, concealment becomes one of the animal’s primary defense system (that is, it always exists regardless of the presence of predators). The concealment of animals is first achieved by the color of their bodies. In many animals, there is a natural protective color, which is actually a defensive strategy adopted by them. Predator animals are usually identified by the appearance of their prey. Therefore, if you blur your outline or mix your body with the environment, it is easier to avoid the attention of predators.
  Natural Invisibility
  in the surface water animal life are often intended color effect is obtained by increasing transparency in the way the body, such as the hydra, jellyfish, comb jellies and many marine fish larvae and many planktonic animals. The water content in the bodies of these animals is extremely high, coupled with their small bodies and low pigments, they look almost completely transparent.
  Why is the concealment method of body transparency more common in aquatic environments than in terrestrial environments? This is mainly due to the difference in refractive index of water and air. If the water content of the animal’s body is high, when light enters their body from the water, the angle of incidence hardly changes, while terrestrial animals do not have such conditions. .
  Even if it is opaque, the body color of most fish helps protect themselves. Fish in the upper layer of the sea, such as herring and tuna, have their backs mostly dark blue, bronze or black, and their belly and sides are mostly silver-gray or white. From the top down, the color of the back of the fish is similar to the dark sea; from the bottom up, the color of the belly of the fish is similar to the bright color through the water. Those fishes living on the bottom of the sea often have their body colors mixed with the colors of the soil, rocks and water plants on the bottom of the sea, and the dim light makes them difficult for predators to find.
  Similar color-like behavior is also common in terrestrial animals. For example, the body of a jerbo in the desert is sandy, and the body of a giraffe that grows in the bushes and savannas of Africa has mottled patterns. Insects also have this ability. For example, the larvae of swallowtail butterfly and cabbage butterfly, the pupae formed in the green leaves are mainly green, while the pupae formed in the brown leaves are brown.
  The color of the predator is consistent with the living environment, which can make them conceal themselves well in order to attack their prey by surprise. Polar bears have been hunting in the ice and snow for many years, and their white fur can make themselves difficult to be spotted by prey such as seals. Cheetahs live in grasslands and have black spots on their pale yellow bodies. They are not easy to attract the attention of antelopes and other herbivores when hunting. The python lives in the forest, with cloud-like markings on its black body, lying on the ground like a rhizome of a big tree, wrapped around the tree like a long vine, and the prey is often sent unknowingly Its mouth…
  In nature, many animals are both prey and predators of other animals. Whether from the perspective of obtaining food or avoiding predation, colorism is an important means for them to improve their survivability and continue their race.   The surrounding environment
  of the “slow” and “fast”
animals of pseudocolor always changes over time, from morning to night, from summer to winter. Therefore, the body color of many animals often needs to be changed with the change of the background color of the external environment in order to obtain a better color matching effect. Many birds and mammals have a special color toning mechanism, which can change different colors of fur or feathers according to the changes of time and environment, so as to maintain consistency with the surrounding environment for a relatively long period of time. This is the “slow color change simulation”. “Color” behavior.
  Some mammals and birds in the Arctic can change color twice a year. In summer, the bodies of Arctic foxes, thunderbirds, and snow rabbits are mainly brown. At this time, they inhabit and feed on rocks and sparse grass; but in winter, when the ground is covered with white snow, they change The snow-white dense winter clothes blend with the vast snowfields. Interestingly, there is also a type of arctic fox whose coat is blue-gray throughout the year. It turns out that this type of arctic fox mainly lives on the coast of the Arctic Ocean, and its blue-gray fur is exactly the same as the blue water. Adaptation plays the role of mimicry.
  There are also some animals that have stronger ability to change color, and can make their body color match the environment anytime and anywhere. This ability is called “fast color mimicry”. The refuge on land and the octopus in the sea are the inventors and masters of this stunt. They only need a very short time, the body color and markings can become completely consistent with the background color, so as to achieve the highest level of color imitation.
  ”Master of Disguise”
  Rescue is a “master of camouflage” in land animals who can adapt to the environment by changing their skin color, making it a “chameleon”. When it is among the green leaves, its body color is green; if it moves to the trunk, its body color will turn into the same yellowish brown as the bark in a blink of an eye. At night, its body color is generally yellow-white; after daybreak, it gradually turns dark green; under the bright sunlight, its body will still shine. It can change the color of the body with the environment, light, temperature or physiological conditions to help protect itself and catch prey. Some types of refuge body colors are particularly rich, including brown, green, blue, yellow, red, black, white and many other colors.
  In terms of makeup skills, no one is an octopus’s opponent. Its body color is bright and changeable, and it can blend its body color into the background environment almost instantly. The secret of octopus discoloration lies in its nerve-controlled polymorphic skin, that is, the skin has variable color patterns and highly complex textures under the precise control of the central nervous system.
  The octopus’s “dispatch station”, which is responsible for changing the scenery, occupies two pairs of brain areas in the brain: the front pair controls the color of the head and wrist, and the back pair controls the color of the body. The left and right lobes manage their own side respectively. If the nerve leading to the pigment cells on the right fails, the color on its right side will be fixed, but the left side can still change into various colors.
  The octopus eye is the direct command organ that adjusts the skin color to match the surrounding background. The visual impression obtained by the eyes enters the nerve center through complex physiological channels, and the nerve center sends corresponding signals to the pigment cells to expand and contract some pigment cells to make them the most suitable makeup color. If one eye is blind, the octopus will lose the ability to control the body color on the same side of the eye; if both eyes are blind, the octopus will almost completely lose the ability to change color. However, the octopus has not completely lost its ability to react to the surrounding colors, because changing the color is not only related to the impression of the eyes, but also related to the suction cup. Even if only one suction cup is left on its wrist, its skin will still be affected. Color reaction.
  When an octopus is in danger, it will try its best to constantly change the color to intimidate the opponent. Whenever life is at stake, octopuses use this color trick to surprise their opponents and even be frightened.
  What’s interesting is that the body color of some lower animals is changed through their food, and the color of the body becomes the color of the food. Sea slug is a small and weird marine mollusk, full of colorful colors. Because they lost the protection of the hard shell, they all rely on changing their body colors to cover themselves. They eat polyps through their tongues, and the pigments of these polyps are expressed on their body surfaces and intestines. So they will always be the same color as the corals where they live.
  Insects also have a variety of mimicry behaviors. For example, the larvae of a hawk moth have 4th instar larvae. The body color of the last instar larva is yellow-green, dark green and white. The dark green is genetically determined, while the yellow-green and white are determined by the environment. Induced polymorphism, the main reason for determining whether the 4th instar larvae is white or yellow-green is the background on which they are resting and the food they eat at the 2nd or 3rd instar.
  The body color of lepidopteran insects (butterfly, moth) is not only rich, but also changes. This change provides more opportunities for survival and reproduction. Butterflies cannot adjust and control the color of their wings through the nervous system. Instead, they have developed structural toning technology, which modulates sunlight through changes in the microstructure on the surface of the wings, showing rich color changes.
  From the perspective of the coloring mechanism, the change of butterfly color is structural color, which is an optical effect caused by the fine structure of the biological body. The microstructures such as ridges and particles on the non-smooth surface of living organisms can cause light waves to reflect, diffract and interfere, thereby producing special color effects. The flickering color of butterfly wings has nothing to do with pigment, it is a masterpiece of the interaction between environment (light) and wings. There are countless small scales on the surface of a butterfly’s wing, which are arranged overlappingly like tiles. Each scale has a row of longitudinal crests, and there are horizontal partitions between the crests, which are divided into nano-scale dimples. The dimples called biophotonic crystals are antiparabolic in cross section, and different parts of the light reflect and scatter differently. effect. The reflected and scattered light will also cause light interference effects in the small concave. It is this wonderful structure that makes the butterfly’s wings glow in bright colors under the sun. The structure of butterfly scales varies from species to species, so the color of butterflies has species specificity.
  The chemical colors of the wings of the giant mormon butterfly are yellow and blue. Why is it green with a metallic luster in human eyes? It turns out that the scales on the wings of the Great Papilio are covered with small depressions of 3 to 4 microns in diameter, the bottom of the depression is yellow, and the surrounding slopes are blue. When light hits the bottom of the concave, it is reflected and turned into yellow. The light hitting the slope of the concave is reflected, and then incident on the other side of the slope is reflected as blue light. Because the concave is too small, it is difficult for the naked eye to distinguish the yellow light at the bottom of the concave and the blue light reflected twice, so the green light can be perceived by humans.