Why do bats make wasp noises? : Weekly donga

In a crisis situation, he secretly hides it so that no one can find him, but sometimes he makes a loud noise or gives strength to his body. It is one of the survival abilities to protect itself, and either hides a terrifying power within, or nothing. The important thing is that these methods can avoid the crisis. In the case of insects and animals that have survived on Earth for quite some time, they tend to use this survival strategy very well.

A variety of strategies have been developed between predators and prey, who are constantly competing to eat each other or not to be preyed upon. The protective color that changes to a pattern or color similar to the surrounding environment is also a technology that has been continued in the same context. The protective color can be used with two main abilities, the ability to hide to avoid natural enemies and the ability to hide needed when hunting prey.

Protective coloration for survival and hunting prey

First of all, in the case of chameleons, which are well known for their protective colors, it was known in the past, like other animals, that their skin color changes by mixing or dispersing the pigments made directly from their body . However, according to recent research results, it has been revealed that a new optical switch that uses different wavelengths of light in changing the crystal structure of the skin to a nano level is the key technology for transformation. The skin of the chameleon has two thin layers that reflect light, and in the process of contracting or relaxing these skin layers, the spacing and structure of a very fine grid change. Light is reflected or interfered in this structure, and the wavelength band is different from the previous one due to the changed light path, and eventually the color of the skin changes dramatically. Under normal conditions, chameleons are mostly green, but when other changes are made to their skin, they turn red or yellow. In this way, the appearance of color without pigment is called structural color, and the color of the body is changed to express feelings of love or anger as well as the influence of the surrounding environment.

Sometimes the purpose of hiding is not to survive, but to hunt for prey. In the case of the orchid mantis, which resembles an orchid flower, it looks like a weak plant, but if you get too close to it, it will be eaten in an instant. The same is true of the native lizard of Madagascar, which cannot be identified when attached to a tree. The black eggplant moth, first discovered in England in 1848, was originally white, but the Industrial Revolution made its main habitat black with coal, and it changed to black as a defensive color to keep out of sight from predators such as birds . The survival rate of light-colored moths decreased and they were eliminated from the environment, and the number of dark-colored moths that survived increased. However, the sudden change in the color of the moth in the evolutionary flow has been an unsolved mystery for 168 years. Scientists analyzed all 400,000 bases that make up the eggplant moth’s DNA and discovered which gene was added to make its wings black.

A life-threatening strategy in a world of eating and being eaten

There is a border color that is the opposite of the protective color. The color of the border is a very striking color, so there is a high possibility that predators will attack. Fortunately, however, those with vigilant colors often hide powerful powers or poisons. Just as we, too, realize that we shouldn’t eat a lot of poisonous mushrooms after being attacked a few times, seeing the colorful colors makes our natural enemies terrifying.

The poison dart frog, which lives in the tropical rain forests of Central and South America, is red or blue and colorful, and although it is only 3 cm in size, it is very poisonous and fatal to people. It got its name because the natives of Latin America used poison dart frogs when hunting animals and used them on their arrows. Interestingly, poison dart frogs cannot make their own poison. Most plants have poisonous substances called alkaloids to protect themselves, and poison dart frogs are said to eat the termites that ingest them, and can only release poison from their skin after processing . This means that young or naturally isolated poison dart frogs are not poisonous. However, if you are a predator who has suffered from poison dart frogs at least once in your life, you will have no choice but to avoid them as soon as you see a colorful and small frog from a distance, poisonous or not, as if you have met a poison skull goal. This is the tremendous power of the color of the border.

imitation disguised as a similar form

There is also a strategy to hide itself in a great way, completely assimilating not only the color but also the shape of the body. One of them is the imitation of performing special appearances or actions to avoid the attack of natural enemies or to frighten the attack target. In the process of considering how to consume nutrients without being eaten by natural enemies, including developed sensory organs and specialized body parts, as well as unusual shapes and behaviors, the desperate feeling of survival can be seen to be involved.

Green grasshoppers hiding in the fields are not easy to spot, and caterpillars and beetles change color, shape, and even shape to match their surroundings. In particular, stick bugs helplessly fall to the ground like a branch falling even if someone touches it. It is a professional mentality that maintains imitation to the end even in a serious, dangerous situation that could lead to loss of life. The chestnut moth, which belongs to the chestnut family, has the same appearance as the fallen leaves. The wings of adults are perfectly like old fallen leaves, so when autumn comes, no one can find them just by attaching them to the ground.

The imitations are usually divided into the Bates imitation and the Muller imitation. Bates mimicry was first discovered by an entomologist named Henry Bates while studying the types of butterflies. When a less dangerous non-venomous or primarily prey animal mimics a dangerous, poisonous or foul-smelling animal, the predator flees to see if it is dangerous. It’s a ‘high risk, high reward’ strategy divided into blackmail and pretentiousness, and can be seen as a terrifying survival strategy where one’s life is at stake.

When a predator accidentally eats a mimicked animal, it is not only poisonous, but also tasty. After that, they try to eat even poisonous and dangerous animals for a while, so they eat all the animals that the predator should have avoided. After being poisonous or smelly for a long time, they do not eat again, but if an animal that mimics again appears in the middle and informs them that there is no problem in eating, the fear that has accumulated in the past disappears. Venomous animals are usually not easily eaten by predators, so the number of individuals has to be increased. However, they are unable to expand their power sufficiently due to the animals that Bates suddenly imitated. Sometimes, I think it was a bee, and when I look at it in surprise, sometimes it is on the back of a flower. They belong to the order Diptera and suck nectar, but they don’t sting like bees. If you look closely, unlike bees, which have four wings, they have two wings like an insect, and the stripes and eyes on their belly are different. This is an imitation of Bates.

Muller’s mimicry was discovered by an entomologist called Joseph Muller, and was created when two types of dangerous animals evolved to resemble each other. Unlike the Bates impersonation, this isn’t a cliffhanger, so it helps each other. For example, if there is a predator that was beaten after eating an animal of a certain color, try to avoid all animals of the same color. In other words, the predator learns the knowledge that they should not eat from both animals faster than usual, and in the end, the ratio of the two types of animals that are eaten in the ecosystem decreases in sudden, which gives an advantage to the conservation of species. This is true of poisonous butterflies and wasps in the tropics.

Just a big challenge for survival, beyond species

In 2019, two butterflies that looked like twins appeared on the cover of the famous international academic journal ‘Science’. The funny thing is that they look very similar, but they are completely different species. One is the long melpomene butterfly (Heliconius melpomene amaryllis) and the other is the red spotted poison butterfly (Heliconius erato). How did these two completely different people get the same color and pattern? No matter how you look at them phylogenetically, the two butterflies are not related at all. Instead, they are just the same predators to watch out for and avoid. Unlike Bates mimicry, where it is clear who copied the Müller mimic, the context of Muller mimicry is unclear, but a joint research team including American and British scientists found that the cause of the same pattern is in ‘gene flow’ ‘ as needed. .

Gene flow refers to the movement of genes from one group of organisms to another. Crossbreeding is the method of gene transfer, where males and females of different breeds or lines are crossed. Although different species, hybridization occurs during evolution, and a common pattern, a type of gene that favored dealing with predators, continues to spread. Perhaps it is an attempt to overcome even the limit of paper for survival.

Even mimicry is not only done between insects. Recently among mammals, the first case of Bates mimicry mimicking the behavior of insects has come to light. Surprisingly, it imitates the sound in the same way, rather than the imitation strategy we are used to. The bat imitates the sound of wasps in order to avoid its predator, an owl. A team of Italian researchers caught a large mouse-eared bat (Myotis myotis) outdoors a few years ago, which buzzed like a wasp when they tried to pull it from its net. Afterwards, I recorded the sound of wasps made by a large mouse-eared bat to an owl, a natural enemy, and tried to move away from the speaker. The researchers speculate that owls have been stung by wasps in the past, and that they are also frightened by the sounds made by the large mouse-eared bats. Even considering the ability of the owl to hear, it is probably much closer to the sound of wasps than we are, and it remains a very unusual example of Bates mimicry in which mammals imitate sounds insects.

Whether they are insects, reptiles, or mammals, if survival is the most important animal, it will do everything it can to survive. This is true whether the original ability is threatening, superior, or not. They were able to exist until now because each of them somehow adapted to the environment in their natural circumstances, devised strategies that were conducive to survival, and tried to live one more day. Sometimes only humans, the main predators of the ecosystem, are mistaken for greatness, but in reality, all living things, including us, win.

_{The track is…
After graduating from Yonsei University’s Department of Astronomy and Space, he worked at the Space Monitoring Center of the Korea Institute of Astronomy and Space Science and Yonsei University’s Space Flight Control Laboratory. Under the stage name of ‘orbit’, he runs the podcast ‘Changchang’, ‘Unfortunate Science’ YouTube and ‘Too Much Science’, and his book is ‘The Science of Orbit’.}

Donga Weekly No. 1356 (p60~63)