Home Fish Facts Do Fish Have Nostrils? (Smelling & Breathing Explained)

Do Fish Have Nostrils? (Smelling & Breathing Explained)

by gvald

You may wonder if fish have nostrils, well yes, but they don’t use them all the time like we do.


They are useful, but they are not used like ours for breathing. The nostrils of fish do not communicate, like ours, with the back of the mouth. Fish breathe by letting water in through their mouth. The nostrils of the fish are extended by a more or less large cavity where the water enters.


In this cavity, there are olfactory sacs that detect and analyze odors in the water. Most fish have two nostrils located at the end of their snout. But some fish, like grouper or perch, have two pairs of nostrils, some located closer to the eye. 


Most fish have an excellent sense of smell. It allows them to detect their food, a prey, a sexual partner, or to recognize, as in salmon and trout, the place where they were born!


What are fish nostrils called ?

The nostrils of fish can also be called nasal cavities, however, this is a term more often used in a scientific context. In general, we do not take the head, we use the word “narrine” simply!


Do all fishes have nostrils?

Even if most fishes seem to have 2 nostrils, just like us, it is not the case of all, there are always exceptions. Some even have 2 pairs of nostrils (so 4), like the grouper, or the perch!


The perfect example is the puffer fish, which have lost their sense of smell throughout their evolution (over hundreds of years), and thus their nostrils which were of no use to them anymore, of course.


Some other fishes have only one nostril, it is the case of Hagfish and Lampreys.


Do fish breathe through their noses ?

The sense of smell (one or two pairs of nostrils) is more developed than sight. The nostrils do not communicate with the mouth and are not used for breathing.


For the reason mentioned above, fish do not breathe through their nose, the gills already take care of this operation. This is quite different from the way we function, we have the choice to breathe through the mouth or the nose. For fish, no choice, breathing is through the gills, and for the sense of smell, it is through the narrins.


Can fish smell like we do ?

Contrary to what is claimed, fish are endowed with both senses of smell and taste: fish can smell water-soluble perfumes. And predators that hunt by smell have long nostrils: the first orifice is near the tip of the snout and the second near the eye.


Aquatic insects emit odors.

They are chemical waves in the form of sexual pheromones.

They guide the hatching and communicate olfactory signals to the fish through the water:

  • Depending on the strength of these signals, they start to hunt their prey.
  • According to the intensity of the hatching, they start to gobble according to the expected insects according to their smell and their preference.

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