alarm substance
Quick Summary
Alarm substances are chemical secretions released by fish, primarily when their skin is injured, that trigger a fright reaction in other fish. This phenomenon was first observed by biologist Karl von Frisch in 1938 with minnows. These substances are detected through the nasal organs and serve as a warning system, particularly valuable for schooling species, helping to protect the group from predators. While often visual or vocal, alarm signals can also be chemical, crossing species boundaries. This chemical communication is a significant factor in the success of certain fish groups, like the Ostariophysi.12
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