Did you know that leaning your ear to the ground, you can hear the sound of the hooves of a galloping horse at a distance of 2-3 kilometers. And the clatter of hooves of a galloping herd of horses is already 10 kilometers away. But provided that there is a relatively flat surface between the listener and the source of the noise and there will be no ravines, waterways and rock outcrops to the surface.
The lateral line in fish allows her to feel the movement of not only other fish nearby, but also the steps of fishermen on the shore, at a fairly large distance. In medieval Japan, carps in decorative ponds near the house were used as guard animals. The fish ponds were only suitable for feeding. The fish, trying to grab food in the flock first, made a noise. And any movement of a stranger near the reservoir, even during the day, even at night, served as an excuse for the fish to start a noisy fuss.
The likeness of the lateral line as in fish is also in crocodiles. But in the form of tiny bumps all over the body and even on the tongue. A crocodile lying at the bottom of the reservoir also feels the movement on the shore and can roughly determine the weight of the one who came up and how many came up. It turns out that the crocodile sees even with his tongue and when approaching the reservoir, one must remember that underwater inhabitants can watch you.
Probably everyone has seen documentaries where African wildebeests and zebras cross rivers and are attacked by many huge crocodiles. The question arises, how could crocodiles gather in one place, at the right time and in such numbers? After all, the annual migrations of antelopes may not coincide in time and the river crossing may be in different places. Again, crocodiles do not like competing neighbors and live alone. Just due to their sensitive bumps on the body, crocodiles feel (hear) the noise of the stomp of thousands of hooves for tens of kilometers and swim along the river to the noise. Crocodiles can live up to a hundred years or more. Large crocodiles over their long lives have learned to use causation and understand that where there is a lot of noise, there can be big food.
In kindergarten, the teacher asks: What color is the crocodile? Little Johnny says: Red. Children in chorus shout that green. And Little Johnny is offended that it is only outside.