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Why cardumen fish react simultaneously

Tropical Fish
Tropical Fish
Big schools are an excellent form of self-defense on the part of fish. Some fish such as piranhas feed on cardumen, while others such as sardines or anchovies defend themselves against the attack of their predators. But the most captivating thing about this group behavior is the simultaneous response of hundreds of fish that make up the cardumen.

The secret of the cardumen movements is hidden in the lateral line of each fish. On either side of their body, each fish has a line with groups of microscopic villi to receive information about their environment. One of the parameters measured by the lateral line is the water pressure.

Rasbora Heteromorpha
Rasbora Heteromorpha

When one of the fish turns suddenly, the water receives a pressure wave. This will be perceived by the other fish and they will accompany the turn instinctively. It is important to highlight the instinct factor. The speed of movement is also due to the fact that the reaction is not premeditated but instinctive. The fish will react to the signals your body gives it.

Other Side Line Functions

Some blind fish, such as Astyanax fasciatus, replace the lack of vision with all the functions provided by this detection mechanism. Blind fish become more dependent on the lateral line, which allows them to find their caves, pairs and food.

© Adrián Blanco 2006 - Prohibited the total or partial reproduction of text and/or images without explicit written consent of the author. —

por Adrian Blanco