Animals also play hide and seek

As children, we all played hide and seek. This game gives a sense of both excitement and fear when one puts oneself in the role of the hunted, and turns into brutality when one switches to the role of the hunted.

hunter ; The goal is to be as undetectable to the hunter as it is to the hunted.

Such behaviors also occur in animals. Predators, predators also fear for their lives, but more indirectly, because if they fail in their hunt, they will starve to death. But is it that easy to be careless?

LSD, Documentary Series


55 min

Blend in the background

Let’s put ourselves in the place of a potential predator, a predator that cannot spend all its time buried at the bottom of a hole or high in a tree. You should take risks just to feed yourself or meet a partner. Not to mention that some species are incapable of climbing trees or making nests, such as gazelles or chamois.

A good option is to be stealthy, trying to blend in with the color of the decor. An easy technique for a wild rabbit or squirrel, for example, is to introduce their dominant color

environment. On the smaller side, some butterflies are amazing because they can blend into the patterns of tree bark. The birch moth, for example, a rather gray butterfly from our region, is almost invisible after settling on the trunk.

Still, if this scenery changes, the risk of reappearance is high. In the spring, the ermine or snow hare is in a hurry to change its fur. Then you need to be more subtle and change the color according to the decor. Octopuses or cuttlefish that can completely mimic their surroundings in a fraction of a second.

French Culture Nights


14 min

Long lasting camouflage

Camouflage provides a beautiful illustration of the adaptation-selection pair dear to Darwin. The most famous example is a small gray butterfly called the birch moth Biston betularia.

Our moth has a habit of blowing a little while landing on tree trunks. On the way

bird if a little too greedy, our dear butterfly risks being seen. From generation to generation, natural selection has favored individuals that blend best into the background and are least visible in a number of variations. They were light gray in color.

Scientific method


58 min

It comes in the 19th century

the industrial revolution with smoke. In L

Industrial England, highways near major urban centers are covered in dark dust. Clearly our moths are visible, the birds – at least the rest – are happy. Within relevant populations, the darkest moths protect themselves passively; dark gray individuals are now more numerous.

A century later, the pollution subsides, the adaptation process is reversed, and our moths are light colored again.

What are the other camouflage modes?

Another camouflage tactic is zebra: adopting a pattern that disrupts the perception of contours. Lions, but also horseflies and Chechens,

biting insects, they are victims of deception. They see the zebra’s coat, but have trouble “lining” it in the middle of the savannah grass, identifying it as a zebra. Tiger stripes or the spots of leopards, jaguars or ocelots have the same role: to play with shadow and light in the bush.

The reason why: science


13 min

Some decorate with the decor itself, like sea urchins covered with sediment grains or remains of Posidonia… Others manage to take on the appearance of an element that has nothing to do with them, but is commonplace in their surroundings. , without being aggravated by external elements… The most well-known are stick bugs, branch-shaped insects that are very difficult to detect.

Sea horsesmany species are also included in this category, mixed with the marine plants they live on.

All these forms of camouflage boil down to “not seen, not detected”. It ranges from fairly primitive camouflage to very successful imitations.

But how to get camouflage?

It’s not enough to say, “I prefer this color or this pattern,” you still have to produce them.

The simplest is with chemical pigments. Your dog is brown, beige or white. The deer is light brown in color. When patterns become as complex as zebra stripes, the coming together of colored patterns begins very early in development.

Borders


5 minutes

Black stripes in zebras owe their color to the presence of melanocytes, which have dark pigment. White streaks are devoid of melanocytes. Melanocytes begin to form in the dorsal region (toward the future spine) a few weeks after fertilization. From there, these cells multiply and migrate towards the abdomen, forming a black stripe.

A classic zebra begins this process at about day 21, and a black stripe develops about every 20 cells along the front-to-back axis. In the mountain zebra, work begins on the 28th day. At this stage, there are already more cells along the anteroposterior axis and therefore there will be more black stripes. In adults, they will be denser and narrower. In Grevin’s zebra, it starts on the 35th day. The bands are thinner and more numerous.

Cuttlefish and octopuses, no matter how complex they are, amaze world scientists with their ability to absorb the color pattern of their environment, but they do it quickly and at the same time have the ability to adopt a mimetic texture. These cells, which change color according to the pressure they are exposed to, are thanks to the developed system of chromatophores. This pressure comes from the small muscles that surround the chromatophores. Everything is controlled by the nervous system through networks of neurons organized hierarchically according to the size of the skin area they control.

Scientific method


57 min

Thus, we see that camouflage is ultimately very sophisticated, can begin very early in embryonic development, and that major adaptive processes are at work over all these selective episodes of species.

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