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A Closer Look at … a Weddell seal’s Nose
Today I learned about the Weddell seal’s unique nose – and it's quite amazing!
Everything about this animal is big – and its nose is no exception. I was most impressed with how wide the seals could flare their nostrils. Scientists have measured the ‘nostril flare’ and said it was about the diameter of a quarter. Of course, I had to see how wide I could flare my nostrils. I’m sorry to say I fell very short – only about the size of a dime. Please, if you try this at home – do not actually stick the coins in your nose!
Alex holding a quarter up to a seal’s nostril. That's quite a large nostril!
Alex holding a dime up to her own nostril. Not even as big as a dime!
There’s a lot going on with the seal’s nose when they surface to breathe.
Weddell seals have an outer and inner nostril – both are very muscular. Here’s what happens when a seal breathes:
Nose Yoga! Image Credit: Terrie M. Williams
- As the seal emerges from the water, the outer nostril appears tightly closed
- The outer nostril starts to open when the seal exhales.
- The inner part of the nostrils flare open when the seal inhales.
- Finally, the nostril snaps shut as the seal prepares to dive.
Check out these pictures of a seal nose in action!
Seal nostrils are very muscular to be able to move like this! Photo Credit: Jennifer Burns
Seal nostrils are very muscular to be able to move like this! Photo Credit: Jennifer Burns
Can a seal smell?
I was just wondering the same thing!?! But first, it might be helpful to understand the basics of how your nose works.
Parts of nose. Image Credit: Educational Guide
- Mammals have special cells inside their noses called olfactory epithelium. Olfactory is a scientific word having to do with smell. Epithelium is a scientific word for a protective layer of tissue – like a skin.
- On the nasal epithelia are special receptors that are sensitive to odor molecules that travel through air or water. These receptors are incredibly small - we have about 10 million in our nose. WOW!
- When the odor molecules reach the special receptors, they trigger the olfactory bulb, or nerve.
- The olfactory bulb then sends a message to the brain, which recognizes the scent.
Our brain can recognize about 10,000 smells! Isn’t it amazing how our bodies work?
Now, back to the seal! Seals have a nose, nasal epithelia and all the parts needed to smell – so they should be able to smell, right?
But think about this!
If an odor molecule cannot get to the receptors to activate the nerve which sends signal to the brain…would you be able to smell? Probably not!
And, if a seal spends a lot of its time underwater, with its nose tightly closed so no water or air can get to the nasal epithelia… do you think the seal could smell – under water? Again, probably not!
Well, what about on land?
Yes, seals can smell on land. And, they probably use their sense of smell to recognize each other during mating season and for a mother seal to recognize her pup.
Close-up of the nose. Photo credit: Chris Burns
On Your Own
Think about it: How are taste and smell related? And, how does raw fish smell? I think seals – which eat cold, raw fish – might not want to smell or taste all of their food!
Go Deeper!
From the scientist, Dr. Burns:
Grey seal nasal cavity. Photo Credit: Jennifer Burns
This is a Grey seal skull, but it provides a good view – looking up the nose of the seal skull. Look how big the area is and see all the thin bones. Those are called nasal turbinates, and in life they are covered with the nasal epithelia. Not only is this where the olfactory epithelia are located, but these nasal turbinates help keep the seal warm and prevent it from getting dehydrated. Pretty nifty for a simple nose!
How do they do that? Well, when a seal breaths out, the air from its lungs is warm (the seal’s body temperature is just like ours ~98F) and moist. But, as the air travels over the turbinates, the temperature and moisture is captured by the capliaries in the epithelia and are retained. The air that is exhaled is drier and cooler than it was when it left the lungs.
Similarly, the nasal turbinates help make the air that the seal is breathing in both warmer and more moist. If you’ve ever inhaled deeply on a really cold day, you know that if you get really cold air into your lungs, you will cough. Seals don’t do this because the nasal turbinates help warm the air as it moves in.
This whole system is called a counter-current heat exchange, and it is a really nifty adaptation that seals have to survive in their cold environment!
The activity/animal depicted was conducted pursuant to NMFS Permit No 87-1851.