How do insects see in the dark?

As an example, let's take nocturnal insects - the size of their visual organs often does not exceed a match head, but they perfectly orient themselves on the terrain in dim light, deftly avoid obstacles and detect even weak movements around.


Imagine that you find yourself in a tropical forest at night, under the canopy of which the light of the moon and stars does not penetrate. It will seem to you that there is not a single source of light around at all. But this will be true only for our imperfect visual apparatus - in fact, the space around will be filled with single photons. For the human eye, their number will obviously not be enough to get at least a dim picture of the surrounding world.

However, the organs of vision of nocturnal insects and animals are much more sensitive. For example, the eyes of the nocturnal tropical bee of the species Megalopta genalis absorb only a few photons, but this is enough to navigate the tangled and dense rainforest even when the light levels are at extremely low values. The European moth, Deilephia elpenor, from the hawk moth family, has a similar behavior. This would not have been possible without certain tricks on the part of the insect.

Using the hawk moth as an example, scientists studied the work of the visual centers of the insect's brain and found that due to the certain work of neurons, the butterfly is able to add single photons into a single picture, which it has caught at different points in space and time. As more and more photons are captured, the picture of the world in Deilephia elphenor's head becomes brighter - it can be compared to a long exposure of a camera when photographing.True, it will not be possible to achieve high-definition images, but the insect can form an idea of ​​the world around it and even see it in color!


This ability, called "neural summation," is shared by other nocturnal insects. Of course, the final image will be far from ideal - for example, fast moving objects will not be fixed, but this way of visualizing the world speaks of how complex and ingenious the visual center of even small creatures is.


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