Sharks are incredible creatures. They have been around for millions of years and are widely considered one of the most terrifying predators in the oceans. Almost everyone has seen a shark on TV or in the movies, and while it may not be the first thing you notice, you have likely seen their nostrils.

These small holes, typically just a bit under their eyes and a little forward, don’t really stand out as being anything weird. In fact, you might not have ever given the shark nose much thought at all.

If you stop to think about it, however, you may ask why their nostrils are there at all. After all, sharks are classified as fish and they don’t breath air. In fact, they don’t have lungs the way mammals do at all. Sharks get their oxygen through their gills, so what are the nostrils doing there?

Well, the simple answer is that they don’t actually have nostrils. Those holes that almost everyone assumes are nostrils are actually called nares. Unlike nostrils, nares are not connected to the respiratory system at all. Like nostrils, however, they are used for smelling things. In fact, the nares are pretty much exclusively used for what we would call smelling.

In humans (and most mammals), smelling is done by pulling air in through the nostrils so that molecules travel over specialized nerve cells, which then get interpreted by the olfactory system. This is such an important system that it has its own sections in the brain.

In sharks, however, water travels into the nares where the specialized olfactory nerve cells are located. From there, the shark brain can determine what molecules are in the water. This is why it is said that sharks can smell blood from a long way away.

When a shark is swimming forward, water is constantly pushed through their nares, letting them know what is in the surrounding area. They have two nares, which allows them to determine which direction a particular smell is coming from, so they can go investigate. Just like air, water travels and spreads out and carries various molecules with it.

So, if an animal is bleeding in the water, small blood molecules get picked up by the ocean currents and when they enter the nares, the shark can identify the direction from which it came.

At that point, whatever it is that is bleeding better hope that they have been able to get out of the water, or at least stop the bleeding and move away, before the shark makes its way over.

It is also important to note that other animals have these nares, including skates, and rays. While their smelling doesn’t work in the same way that ours does, it is still an effective way for them to learn about the surrounding environment so that they can survive.

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