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..Why do fish have nostrils if they can't sniff?





LittleBlackKitten
This is perplexing my mind...Laughing
deanhills
Probably so that they can blow bubbles ..... Laughing
Ankhanu
The answer is related to thefact that the question is flawed.. some can sniff, others smell more passively, not drawing water over the nostrils to smell. There are even fish with inflow and outflow nostrils.
menino
Something does smell fishy about this question..... Laughing

I guess Ankhanu is right - perhaps some fish have use for their nostrils, but even the great white shark has nostrils and gills.
Probably the nostrils are used as sensors, as fish have a great sense of smell under water.
Sharks may not have to sniff... and if they do, I don't think their prey would want them to. Very Happy
watersoul
I don't see it as too mysterious really. Any part of any body that is designed to sense something would ideally have a clear line to the thing it's supposed to sense. Nostrils provide our brain with that small safe opening to the outside world of smells, whether in the open air or underwater.
LittleBlackKitten
What I meant was they don't sniff like dogs or catch colds... Laughing

I know they can SMELL, but that is more like a radar.
watersoul
Our nostrils aren't just for sniffing though, they're the opening in the body which allows access for the odorous molecules we detect in our sense of smell...exactly the same use for most fish even if they never actually sniff, sneeze, or blow their noses Laughing
LittleBlackKitten
I think I would faint if one of my babies sneezed...I'd think they're having a heart attack! Laughing
watersoul
LittleBlackKitten wrote:
I think I would faint if one of my babies sneezed...I'd think they're having a heart attack! Laughing


...would definitely be a messy sneeze! Laughing
PGe-tips
I guess it originates from a function that is lost during evolution.. similar as why men have nipples while they don't breastfeed ... honestly I don't know and don't wanna know Smile
Ankhanu
PGe-tips wrote:
I guess it originates from a function that is lost during evolution.. similar as why men have nipples while they don't breastfeed ... honestly I don't know and don't wanna know Smile


Not at all... it was the starting point in our nostil evolution, and they're fully functional. Nothing was lost in evolution, rather they've been refined through time.

http://www.nature.com/nature/journal/v432/n7013/full/nature02843.html?free=2

Yeah, "sniffing" and sneezing don't happen, but, yeah, they're functional anatomy.
ocalhoun
LittleBlackKitten wrote:

I know they can SMELL, but that is more like a radar.

Confused

Radar works by sending out pulses, then listening for the echoes...

What does a fish's sense of smell send out? And how does it echo?
jwellsy
You can pick your nose,
and you can pick your friends,
but you can't pick your friends nose.

This may not be true in the fish world. I doubt they can pick their own noses, they probably have to get a buddy to do that for them.
deanhills
Ankhanu wrote:
The answer is related to thefact that the question is flawed.. some can sniff, others smell more passively, not drawing water over the nostrils to smell. There are even fish with inflow and outflow nostrils.
This is interesting to me Ankhanu, particularly since I love diving. Do you think fish with inflow and outflow nostrils could use these to increase and decrease their buoyancy in the water?
Ankhanu
Nope; it's just in, over the olfactory sensors and out.
When I went to refine my memory of fish anatomy yesterday, I realized that in/out 4 nostrils is the norm rather than exception.
LittleBlackKitten
Quote:
You can pick your nose,
and you can pick your friends,
but you can't pick your friends nose.

This may not be true in the fish world. I doubt they can pick their own noses, they probably have to get a buddy to do that for them.


I guess they'd have to latch on and suck Laughing!

Quote:
Radar works by sending out pulses, then listening for the echoes...

What does a fish's sense of smell send out? And how does it echo?


I meant in the sense that they can't just inhale and smell something; at least not in my brain since they only have gills and not lungs. I could be wrong, I'm no expert on fish noses, Laughing. I guess it's more of a "there is iron in the water, coming from over there" instead of "Oh hey, I smell iron. *sniff sniff* where's it coming from? *follows smell* Oh there it is!" like a radar - they sense the scent, and know it's there....I guess that's how salmon find their spawning grounds?...

I dunno...Lol...
Ankhanu
There are three mechanisms that they use to move water through their nares:
.: passive, water moves through as they move forward.
.: ciliary action, tiny hairlike structures pump water through
.: water pumps, accessory organs pump water through
.: additionally, SOME rays or bottom dwelling sharks have the 2nd nostril opening into the mouth, drawing water through when they draw water over their gills

In all but the first, the fish is actively moving water through, just like we actively move air over our olfactory sensors, but it's not connected to breathing like ours. They can actively work to "sniff" if you will to home in on odours.

When I get home this weekend, I'll see if I can find my ichthyology text book (I'm in the process of moving) and provide some better clarity.
deanhills
Ankhanu wrote:
When I get home this weekend, I'll see if I can find my ichthyology text book (I'm in the process of moving) and provide some better clarity.
Am looking forward to it! Great thread as I have never questioned why fish don't seem to need any weights to stay under the water. So would be great to figure out how they manage to adjust, including those who are really deep down in the ocean where it is mostly dark and pressure is much higher.
Ankhanu
deanhills wrote:
Ankhanu wrote:
When I get home this weekend, I'll see if I can find my ichthyology text book (I'm in the process of moving) and provide some better clarity.
Am looking forward to it! Great thread as I have never questioned why fish don't seem to need any weights to stay under the water. So would be great to figure out how they manage to adjust, including those who are really deep down in the ocean where it is mostly dark and pressure is much higher.


Buoyancy is regulated in a variety of ways, though it's generally needing to increase buoyancy, rather than decrease it like we have to with weights; they need to regulate so they don't sink.

Most sharks and the like actually use their fins and their near constant motion to keep from sinking. The pectoral fins act like wings providing lift. Fats and oils in their flesh and in deposits help reduce overall density and provide some buoyancy too.
Teleosts (bony ray finned fish) use some fin regulation and fats/oils too for buoyancy, but many make use of a bladder in their body cavity known as a swim bladder, which can be inflated and deflated with gasses to help them maintain, increase or decrease buoyancy. In most, this bladder is not open to the outside, gas exchange is through capillaries moving them it and out of the blood. There are some fish, however, in which this bladder is connected to the respiratory system, and they can draw air in through their mouths at the surface and into the bladder (like the lungfishes and even popular aquarium fish like Bettas and gouramis). This has more to do with breathing in O2 poor water than it has to do with buoyancy though.

http://en.wikipedia.org/wiki/Swim_bladder

Seems wiki may be better than my memory... gas exchange to the bladder isn't via capillaries, but via a gas organ; there are few vessels in the bladder wall.
jwellsy
Do fish ever get a runny nose?
wawcff
what's perplexing???????
LittleBlackKitten
To perplex means to cause stress, worry, confusion, or wonder, in a milder sense. Like, "The math problem my teacher gave me had perplexed me; what was the answer?" or "Why that little girl was running up and down that hill so quickly perplexed me; wouldn't she get hurt? What perplexed me further was that her mother wasn't stopping her."
D'Artagnan
just because they don't breathe doesn't mean they don't have scent, piranha and sharks use blood to can smell blood - at least that's what dan brown told me
Greatking
This is the explanation i got when i enquired.

Apparently they do have openings on the face that allow them to smell, but these are called "nares" in fish. It's a little different in fish, which doesn't have the same set of sensory organs as mammals.
IceCreamTruck
This is a very strange thread! I'm oddly speechless...
Radar
I'm familiar with the idea of sharks smelling blood. It just gets odd when we typically think about smelling as detecting tiny particles in the air, and then... well... transferring that idea to water.
IceCreamTruck
Radar wrote:
I'm familiar with the idea of sharks smelling blood. It just gets odd when we typically think about smelling as detecting tiny particles in the air, and then... well... transferring that idea to water.


Sharks have sense organs all around their mouths which help them "smell". It's different then smelling air because it takes very little water to move past their sense organs to pick up the smell. It's not like our noses which are designed to manually move lots of air past our olfactory sense organs so we can detect certain concentrations of particles.

Their sense organs are exposed, and ours reside in the air channels of our nostrils.
Ankhanu
IceCreamTruck wrote:
Radar wrote:
I'm familiar with the idea of sharks smelling blood. It just gets odd when we typically think about smelling as detecting tiny particles in the air, and then... well... transferring that idea to water.


Sharks have sense organs all around their mouths which help them "smell". It's different then smelling air because it takes very little water to move past their sense organs to pick up the smell. It's not like our noses which are designed to manually move lots of air past our olfactory sense organs so we can detect certain concentrations of particles.

Their sense organs are exposed, and ours reside in the air channels of our nostrils.


What you're thinking of are the ampullae of Lorenzini, which are electroreceptive organs, i.e. they sense electrical impulses in their prey (i.e. nerve and muscle signals). Olfaction is still centered in the nares.
deanhills
Ankhanu wrote:
What you're thinking of are the ampullae of Lorenzini, which are electroreceptive organs, i.e. they sense electrical impulses in their prey (i.e. nerve and muscle signals). Olfaction is still centered in the nares.
I like it .... ampullae of Lorenzini. Sounds almost poetic, especially for a shark ..... Twisted Evil
IceCreamTruck
deanhills wrote:
Ankhanu wrote:
What you're thinking of are the ampullae of Lorenzini, which are electroreceptive organs, i.e. they sense electrical impulses in their prey (i.e. nerve and muscle signals). Olfaction is still centered in the nares.
I like it .... ampullae of Lorenzini. Sounds almost poetic, especially for a shark ..... Twisted Evil


Yeah, they can feel your heart beat with those! Resistance is futile!

I read somewhere that sharks "smell" blood with organs around their mouth, and what's bothering me is that I am NEVER wrong! Smile Haha, just kidding.
deanhills
IceCreamTruck wrote:
I read somewhere that sharks "smell" blood with organs around their mouth, and what's bothering me is that I am NEVER wrong! Smile Haha, just kidding.
I wish the biologists could give the "mouth" of a shark a different name. Does this look like a mouth to you? Looks more like a razing factory to me ..... Twisted Evil

Ankhanu
Buccal cavity?

Though what you're referring to is the jaw more than the "mouth", I suppose Wink </pedant>
IceCreamTruck


No doubt this is why we walk on land. If I was a fish I would grow legs too! Smile
LittleBlackKitten
Lmao. You mean you'd be like the Little Mermaid?
IceCreamTruck
LittleBlackKitten wrote:
Lmao. You mean you'd be like the Little Mermaid?


She didn't grow legs... she wished bartered for legs with her voice! "If I was a fish" generally implies that I am not, but if you think it means I am already a fish, then go with that because that is more fun! Smile

That's not a fork, it's a Dinglehopper!! Human's use it to comb their hair!

I'm having FLOTSAM & JETSAM over for dinner, LBK, would you join us?
LittleBlackKitten
As long as they don't try and taste me! Ha ha ha.
IceCreamTruck
LittleBlackKitten wrote:
As long as they don't try and taste me! Ha ha ha.


You wanna take this one, Ankhanu? The door is WIDE OPEN! Smile

Just kidding, LBK, but you saying that made me laugh!
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