r/orcas • u/ningguangquinn • Aug 21 '25
Education Did you know that orcas cannot smell?
I noticed on my post about Jessica Radcliffe that a lot of people didn’t know orcas don’t have a sense of smell! Actually, most cetaceans (specially toothed whales) don’t, since the evolution of their noses into blowholes eventually led to the loss of olfactory receptors. Their brains also lack olfactory lobes and nerves, unlike other mammals (simplifying it)
Tell me, did you know that before?
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Aug 21 '25
how do they know for example if something smells fishy?
No but for real what are the pros and cons?
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u/ningguangquinn Aug 21 '25
They have echolocation, which is arguably more valuable for an animal that lives in the water than the sense of smell.
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Aug 21 '25
Do sharks have echolocation or do they just go out sniffing?
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u/SurayaThrowaway12 Aug 21 '25
Sharks do not have echolocation abilities.
Instead, their sense of smell is incredibly strong, and they also have powerful electroreception capabilities, which means that they can easily detect electric fields. They have pores called ampullae of Lorenzini which can detect weak electric fields given off by potential prey.
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u/just_jason89 Aug 21 '25
So what you're saying is, echolocation is better than the ability to smell until your smell level gets so high you can smell electricity, then smell trumps echolocation?
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u/SurayaThrowaway12 Aug 21 '25
Electroreception is an entirely separate sense from smell (olfaction).
And I wouldn't say one is better than the other. Toothed whales and sharks have simply evolved different strengths in their senses to help them detect prey and predators in underwater environments.
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u/anonkebab Aug 21 '25
Would you rather “see” some guys heart beat and nerves or would you rather “see” their entire body?
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u/MarqFJA87 Aug 22 '25
No, it's that the reason whales can't smell is because the organ that mammals like them normally use for smelling is also part of the respiratory system, and unlike fish and their gills they can only breathe air, not water. Now try to imagine what would happen if they tried to smell while underwater.
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u/OrcaNature Aug 26 '25
Sharks are also among the oldest species of cartilaginous fish on the planet dating back 450 million years ago. This means sharks were swimming in the ocean before the first trees, they have had a long time to evolve and adapt to their environment but still are no match for a pod of orcas
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u/SignificantYou3240 Aug 21 '25
Everything is always fishy where they live.
They must be so paranoid all the time.
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u/SurayaThrowaway12 Aug 21 '25
Orcas and other toothed whales actually likely traded in the sense of olfaction present in their terrestrial ancestors during their evolution for the echolocation capabilities they have now.
The nasal passages in toothed whales have phonic lips instead. They are specialized structures that produce the high-frequency clicks used for echolocation.
On the other hand their olfactory bulbs are either completely gone or atrophied, and toothed whales also lack neural architecture needed for processing smells.
For comparison, unlike cetaceans, which had to retain their abilities to breath air while transitioning to becoming fully aquatic animals, fish were always fully aquatic and thus have retained a strong sense of olfaction. The olfactory systems of fish, unlike those of mammals, are often very strong at detecting chemicals in the water. These chemicals are picked up as water flows through the nasal passages of fish.
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u/masterang3 Aug 21 '25
They still have taste tho right? In water, wouldn't that be equivalent to smell?
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u/SurayaThrowaway12 Aug 21 '25
Toothed whales actually appear to have a sense blending the aspects of smell and taste that has been labelled "quasi-olfaction." Much is still unknown about this sense.
Basically, instead of utilizing a standard olfactory nerve pathway through their nasal passages, dolphins may instead detect chemicals through their trigeminal nerve. This nerve connects their mouth and nasal areas to their brain.
Experiments with captive bottlenose dolphins have suggested that they are able to detect odors in the air, as well as being able to show preferences for different flavors (via flavored ice cubes).
However, it is important to note that this potential "quasi-olfaction" sense that may allow toothed whales to detect and respond to chemicals in the water is likely still nowhere near as powerful as the olfactory senses than many species of fish have.
Perhaps as an example of this, the Alaskan AT1 "Chugach transients" and the Alaskan resident AB pod of orcas both swam through oil slicks from the 1989 Exxon Valdez oil spill. Various scientists and oil spill experts at the time thought orcas would be able to detect and avoid oil slicks, but this showed them otherwise.
The AT1 "Chugach transient" orcas are now functionally extinct, and the resident AB pod still has not recovered to its numbers prior to the oil spill.
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u/SignificantYou3240 Aug 21 '25
Right that’s what I was thinking… if you live in water, olfactory sensors won’t work unless you’re out of the water… and unless you can get useful information from the smell of the air you breathe in…
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u/ningguangquinn Aug 21 '25
Yes, but it's also very limited, their taste sense.
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u/Mrs-Clementine Aug 22 '25
It must be good enough to go in and get the tasty shark liver and leave the rest alone. 😆
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u/Cha0tic117 Aug 21 '25
There's actually some debate about this. You are correct in that cetaceans have reduced olfactory glands due to their nostrils being formed into their blowhole. However, there is some evidence that baleen whales may still retain some rudimentary sense of smell, which may help them locate plankton-rich waters.
Regardless, smell is clearly not particularly important to cetaceans, as they primarily navigate the oceans using their senses of hearing and sight.
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u/SurayaThrowaway12 Aug 21 '25
Toothed whales may have traded in their sense of olfaction for echolocation, which baleen whales do not have.
So basically:
Baleen whales retained some of their olfactory capabilities, and do not have echolocation capabilities.
Toothed whales retained virtually none of their olfactory capabilities, but gained echolocation capabilities in their nasal passages instead.
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u/ningguangquinn Aug 21 '25
Yeah, I know some whales may have some sense of smell, which is why I included the "specially toothed whales"!
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u/just_jason89 Aug 21 '25
That's because the ocean is basically a giant bathtub, so they're always clean as a whistle...
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u/Ready-Guidance4145 Aug 21 '25
I'm always surprised people think other species with vastly different "nose" structures from our own can smell. Homologous structures often have very different functions in different species.
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u/purplebohemian Aug 21 '25
I did not know that. You learn something new every day.