There is light and it’s stealth.

  Excuse me for invisibility cloak
  Speaking of stealth, you probably think of Harry Potter’s invisibility cloak, in the wizarding world, invisible cloak made from the hair of the beast is made to make invisible people or things it covers. In the animal world, some animals also have invisibility cloaks, but their invisibility cloaks come from light. Most of these animals that use light as invisibility lie in the ocean.
  For small animals in the ocean to avoid stealth and avoid becoming a natural enemies, there are generally three options. Small animals living in the deep sea of ​​black scorpion, or bury themselves in the mud; or hide in rocks; or hide in the coral. In the deep sea near the bottom of the sea, the sun is hard to reach, so the predator in this dark and deep sea either has no eyes or has very weak vision. Therefore, as long as the small animals find a hiding place, they can generally avoid the enemy’s pursuit. The small animals that live near the sea are different. There is plenty of light. Their way of avoiding is to let themselves shine. For example, the luminescent bacteria on the ear thief can emit the same light intensity as the surrounding light, making the ear squid invisible in the eyes of the predator. of.
  However, some small animals live in a deep sea area that is far from the sea and not close to the sea floor. The light here is weak and there are no sediments or coral tracts to hide. The above two stealth methods are not applicable. They can only take a different approach and put themselves in invisibility cloaks made of light. Light stealth is done by allowing light to penetrate the body completely, making it transparent, and the light can’t be reflected in the predator’s eyes. Predators can’t see them. It’s like when you walk into the mall door, you know what’s in front of you. No, I walked forward and bumped into something. There was a transparent glass door there. The light didn’t reflect into your eyes. If you couldn’t see the glass, you thought there was nothing, and you hit it.
  Let light pass through the body
  In the ocean, there are many animals with deep and transparent ways, and glass octopus is one of the best. Glass octopus, as its name suggests, is almost completely transparent. Glass octopus lives in the tropical and subtropical waters of 300 to 1000 meters, including tentacles, up to 45 centimeters in length. This octopus is transparent except for the digestive organs and eyes. You may think that since the digestive organs and eyes are not transparent, what is the point of making the body transparent? Can a predator not see it? To make matters worse, these organs cast shadows under the water. Doesn’t this make them easier to notice? These are indeed problems, but there is no way, glass octopuses need eyes to converge and not transparent. Therefore, it can only hide its eyes. The glass octopus does not have round and large eyes like other kinds of octopus. Its eyes are extremely slender, which ensures that the projection of the eyes is small enough to make it difficult for predators to pay attention. To. The reason why organs are opaque is because they contain food eaten by octopus. These foods that are about to be digested generally do not attract the interest of predators.
  In the ocean, not only glass octopus, but also glass squid, there are more types of glass carp, about 60 kinds, living in the sea area 200 to 1000 meters below sea level. Glass squid is similar to glass octopus, allowing light to pass through its body and its eyes are not transparent. Unlike glass octopuses, glass squids have round, large eyes, so how do they hide their big eyes? Under the eyes of the glass squid, there is a special illuminating organ that emits the same light intensity as the surrounding environment, which is invisible, similar to some animals living near sea level. The predators swimming below can’t see the glass squid, but the large eyes of the glass squid allow them to “see the six way” and capture the position of the predator from other angles to escape.
  In addition to glass octopus and glass squid, there are many marine creatures that have a transparent ability, such as a floating silkworm that looks like a fin, a sea otter that looks like a sea otter, but sometimes it is not enough to avoid predators. . In the mid-depth waters, some animals have their own lighting equipment, such as fish with long “lights” on their heads. The animals that are transparent under the surrounding light are illuminated by the lights of the fish. This is because the light transmission is affected by the frequency and wavelength of the light, and the light emitted by the fish’s lamp is different from the frequency of the surrounding light, and the light transmission is changed, and they are naturally seen. Therefore, to avoid these predators that will shine, there must be new tricks.
  Nanoscale cloak
  stealth method of long foot 8 pairs Amphipoda complex organisms than transparent, they are wearing nanoscale cloak. Scientists have observed amphipods with electron microscopy and found that their legs are covered with nanoscale hairs ranging in diameter from 100 nanometers to 300 nanometers. Scientists have found that these nanoscale hairs can reduce the reflection coefficient by more than 100 times and minimize the scattering of light, so that the body does not reflect enough light into the predator’s eyes to escape the birth. However, scientists believe that these hairy hairs are probably not grown by the amphipods themselves, but by some kind of symbiotic bacteria covering their legs. That is to say, the nanopokers of the amphipods are actually bacteria.
  Ye Shuiyu also has nano-level invisibility cloaks, but their invisibility cloaks are not stable. If you look closely, you will find that Ye Shuiyu is flickering. Why? Ye Shuiyu is known as “aquamarine”. They have a splendid color, but they will suddenly disappear. This is because the skin of the leaf leeches is covered with layers of hexagonal tiny guanine crystals. The cytoplasm is separated between the layers, and the thickness of the guanine crystals is the same, both 70 nm, but the cytoplasm thickness varies from 50 to 200 nm, forming a unique microscopic layered structure of the cytoplasm. It is the different thickness of the cytoplasmic layer that affects the different colors of the leaf leeches. The thicker cytoplasmic layer reflects longer wavelengths of light, while the thinner ones are opposite. After many experiments, scientists have found that the color of leaf leeches depends on the angle of incidence of light. When the light is incident at 0°, the leaf leeches are blue-violet, and when the angle of incidence is 45°, the reflected light belongs to ultraviolet light. The human eye can’t see it, most animals can’t see it, and the leaf leeches are invisible. Imagine that the natural enemies of Ye Shui-soo saw the brightly-colored leaf leeches and rushed to the scene, only to find that the leaf scorpion that was still gleaming suddenly disappeared, and soon appeared again, flickering, suddenly left Right, it can’t correctly capture the position of the leaf leeches. Is it a bit different from playing with a cat sticking your cat?
  Read here, you will find that the animals that use light invisibility mentioned above live in the ocean. Is there such an animal on land? Yes, but very few.
  Land animals is difficult to excuse me invisible
  Why invisible little animals on land it? This is because to be transparent, it is necessary to absorb neither light nor light. It is a difficult task for animals and plants on land. Generally speaking, the higher the density of objects, the larger the refractive index. The average density of air is 1.29 kg / m 3 , and the average density of organisms such as the human body is about 1050 kg / m 3 , the density difference between the two is large, which causes a large gap between the two. When light passes through the tissue from the air, it is more prone to refraction, scattering, and reflection, and the organism is more easily seen. In the ocean, the refractive index difference between seawater and some marine animals is small, and it becomes easier for them to become transparent.
  In addition, animals living on land should face the sun. They need pigments such as melanin to protect against the radiation damage caused by sunlight. Animals in the ocean have sea water to help them absorb radiation.
  There are always exceptions to everything. Transparent animals on land are rare, but they do exist. The glass wing butterfly that lives in Central America is a special case. Although only the wings are transparent (except for the edges of the wings), the transparent wings are sufficient for them to escape the predator’s tracking. The reason why the wings of the glass wing butterfly are transparent is because the wings are covered with small particles of nanometer scale, and the effect is the same as that of the nanopockets of the amphipods. In addition, in Croatia, scientists have also discovered a translucent snail that lives in a dark cave. Although translucent, it is still visible enough to see how difficult it is to make invisible light on land.