Home Fish Science Can Fish Smell Odors? (Helpful Examples)

Can Fish Smell Odors? (Helpful Examples)

by gvald

Well yes, fish can smell, I mean can feel what surrounds them in the water. Their sense of smell is even very developed!

 

Fish can detect odorous molecules in the water. Like humans, their sense of smell is achieved thanks to olfactory sensory neurons present at the bottom of their nostrils.

 

Thanks to various studies on the subject, we know that their olfactory system allows them to detect very light odors, and for some species from very far away. For example, sharks can smell blood from several hundred meters away.

 

Thanks to their sense of smell, some fish also detect social signals emitted by their fellow fish. Thus they can detect the “alarm substance”, a molecule emitted by the skin of some fish when they are injured.

 

How do fish sense odors?

Even though they live in water, fish are, like us, able to detect odorous molecules that circulate in an aquatic environment, thanks to olfactory sensory neurons nestled (still like us) in a mucous membrane located at the bottom of their nostrils.

 

Numerous works have studied the sense of smell in fish. It appears that their olfactory system allows them to detect very low odoriferous concentrations, almost homeopathic: from 10^(-5) to 10^(-10) mole per liter, depending on the species. And this, over long distances. Thus sharks can smell blood over very long distances.

 

Can a fish smell bait?

Even though fish have a well-developed sense of smell, there is not much chance that they can smell a bait, in the sense of a threat.

 

It is also unlikely that they can distinguish a bait from another small fish, the vision of fish is not as developed as their sense of smell, some scientists agree that their vision is only made of variations of different grays.

 

Impact of CO2 on the sense of smell of fish

The oceans absorb about a quarter of the planet’s CO2. This increases their acidity. Studies have shown that these alterations in the chemical composition of the ocean impact the behavior of some fish, even going so far as to be attracted by the smell of their predators, explains the scientist.

 

Fish exposed to high amounts of CO2 were less able to detect eight of the ten introduced odors (including that of their predator). Their sense of smell was reduced by half.

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