If we take a glass of water from a fish tank inhabited by a shark and pour its contents into another tank inhabited by bass, we will see how the animals go crazy, swimming at high speed and colliding with each other and the walls. Some fish may even jump out of the tank. They are able to perceive the scent of the predator.
What is astonishing is that if we repeat the same operation in a tank inhabited by captive-bred bass, animals that have never been in the sea, the result will be exactly the same. This experiment demonstrates that fish genetically obtain a record of the predator’s scent. This is quite logical because if a mouse knew what a cat smells like from having sniffed it before, it would no longer be alive. Perhaps the bass do not know they are fleeing from a shark, perhaps they do not even know what a shark is, but they are fleeing from the «scent of danger.»
Almost all marine animals have a very keen sense of smell. Their life, death, feeding, and even reproduction depend on it. Without some form of communication, both mating and reproduction would be purely random. Pheromones are subtle aromas emitted by certain species to attract potential sexual partners. It is believed that these chemical substances contain vital information about the intruder’s species, sex, age, and reproductive state.
Both prey and predators, as well as animals involved in reproduction, are guided to some extent by their sense of smell. In the deep abyss where there is no light, smell can be the only indicator of a dangerous presence or a congenial mate ready to reproduce. It could be said that life and death in the sea hang by a delicate scent.
The pollution of the sea caused by human beings poses a great threat to all marine animals due to the acute sensitivity of the receptors that detect pheromones. Their biological processes, and even life and death, depend almost entirely on chemical communication. Living in a polluted sea is similar to trying to cross a smoke-filled street, where the chances of reaching the other side are minimal. It is our obligation to control that smoke, as it is our fire.
«One cannot defend what one does not love, and one cannot love what one does not know.»