The debate regarding whether or not cetaceans (whales, dolphins, and porpoises) can smell has existed for decades due to a lack of scientific information.
For most people, smell involves inhaling an odor through our olfactory senses.
For many, this means inhaling a scent through the air.
However, we also hear that sharks can smell blood underwater, so how do they do it, and does that mean that whales are also capable of smell?
For a long time, scientists and researchers believed that whales, dolphins, and porpoises could not smell.
This belief in a whale’s inability to smell came from the fact that most research on this topic came from research on the toothed whale species, which scientists concluded lacked the hardware required for whales to smell.
Because of this information, scientists were led to believe that whales could not smell anything.
However, a recent study done by professor Hans Thewissen of the Northeastern Ohio University College of Medicine and colleagues has shown that the bowhead whale (a baleen whale) is, in fact, capable of smelling.
During an experiment to examine a bowhead whale’s brain, they discovered that all of the components necessary to smell were present.
Since smell appeared to be unimportant to their survival (echolocation plays a significant role in a whale’s ability to find food, navigate the ocean, and survive), they were surprised that these olfactory functions remained in the bowhead whale’s brain/head.
One hypothesis as to why this whale can still smell is due to the belief that the whale uses its sense of smell to locate krill, a food source these whales thrive on.
This discovery has led to many new questions regarding the baleen whale species and their ability to smell.
However, there is still no sufficient information indicating whether or not there are any species of toothed whales capable of smell.
Surprisingly even though toothed whales are still believed to be incapable of smell, some species show a strong preference for certain types of food, indicating that they may be able to taste their food and distinguish the flavors of various foods.
Since smell and taste are often closely related, these findings open up new questions about the cetacean species’ taste buds and olfactory senses and what we can learn from them.
The ability to taste food has been chiefly observed from feeding dolphins in captivity.
When feeding them various types of fish, some dolphins prefer one type of fish over another. Since whales, dolphins, and porpoises all belong to the same cetacean family, whales may also be able to taste their food.
If these marine mammals have well-adapted taste buds, it may be possible for them to taste (sense) certain types of nearby food, much like a human can smell cake baking in the oven.
When it comes to our sense of smell, humans rely more on their ability to smell their foods to determine how it tastes.
Without the ability to smell, our capacity to taste our foods would diminish significantly, with many foods tasting almost exactly alike.
Animals such as snakes are known to smell using their tongue by waving their tongue in the air and detecting scent molecules.
The snake can detect where the scent comes from by waving its tongue back and forth.
The scent molecules picked up get sent to Jacobson’s organ, which sends the information to the brain, allowing the snake to smell odors and detect where it is coming from.
Although this same ability is speculative among the cetacean species, it is essential to know as it can help us understand more about these marine mammals and whether they can detect distant prey through taste.
They may also detect food from a distance by tasting the water molecules around them.
However, even if they can taste the water molecules around them, they may still rely more heavily on echolocation to locate their prey.
Lastly, when it comes to whales being able to smell, these marine mammals are believed to be the descendants of land-dwelling animals.
The earliest ancestors of whales appear to have walked, hunted, and survived on land and most likely could smell various odors in their environment with their nostrils and olfactory glands.
Due to this fact, whales may be capable of smelling or at least detecting food and threats similar to land-dwelling animals.
However, until sufficient research can provide a conclusive answer to this hypothesis, we will have to rely on educated guesses and the limited information at our disposal.
So How do Whales Smell?
As stated earlier, our understanding of whale smell is relatively new, and it is still believed that a large percentage of cetaceans are incapable of smell.
One of the most important differences between species such as whales and sharks is that marine mammals such as whales breathe very differently from sharks.
Since whales are marine mammals, they require air to breathe and must hold their breath underwater.
On the other hand, Sharks have gills that extract oxygen directly from the water.
Because of this fact, whales (like humans) cannot smell when they are underwater.
When the whale rises to the water’s surface, it exhales old oxygen and takes in the fresh air.
During this time, it is likely that species containing good olfactory senses inhale various odors that help them detect the locations of large groups of prey.
The role in their ability to smell, however, is less understood.
Whether or not these marine mammals rely on smell to locate food is unknown.
However, it may make sense for them to rely on smell if they do not have echolocation abilities or their ability to echolocate is limited.
It was believed that baleen whales were incapable of echolocation for a long time, but new research shows that some baleen whales may also possess this ability.
But What about Sharks?
Unlike whales, sharks can smell underwater by detecting the scent molecules that disperse in the water bypassing the scent-laden water through their nasal cavities or nares.
The amount of time it takes these molecules to reach the shark’s nasal cavities depends on the current’s speed, direction, ferocity, and the number of molecules in the water.
Once the shark can detect an odor, it begins swimming toward it by moving its body from left to right.
This snake-like movement allows the shark to determine whether it is on or off the odor trail so that it can figure out exactly where the odor is coming from.
Dogs are also known to move from left to right when located at the source of an odor to ensure they are headed in the right direction.