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Nostrils

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Gray
54404.  Wed Feb 22, 2006 10:07 am Reply with quote

Question: How many nostrils do you have?
Forfeit: Two.
Answer: Four.

Notes: Most modern fish have two pairs of nostrils, one set for letting in water to their gills, and another hind set that let the now de-oxygenated water back out again. If, as all the evidence suggests, we are evolved from fishes, where did the other pair of nostrils go?

The answer is that they migrated through the teeth, and up inside the nasal cavity to become internal nostrils called 'choannae', and it's these features that now allow us (or most of us) to breathe through our noses - the nostrils connect our nasal cavities with our bronchi.

Min Zhu of the Chinese Academy of Sciences in Beijing and Per Ahlberg of Uppsala University in Sweden have found a fish (Kenichthys campbelli) that shows this nostril migration in progress - a 395 million year old fossil that is an intermediate form between fishes and tetrapods, whose tooth line is indeed split apart by a pair of wondering nostrils.

This intermediate step meant that early air-breathers were able to stay in shallow, deoxygenated water and eat, but put a pair of nostrils into the air to breathe in more oxygen, like crocodiles.

Sources:
http://www.bioedonline.org/news/news.cfm?art=1357 (from Nature)
http://scienceweek.com/2004/sa041224-3.htm

 
Flash
56287.  Wed Mar 01, 2006 8:06 am Reply with quote

Mat points out a picture on p22 of FT#205 of a dog with two noses - or rather one nose but split into two like a double-barrelled shotgun. The picture is credited to 'The Scientific Exploration Society' and is captioned as 'a double-nosed Andean tiger hound'. Apparently it is not a deformed individual but an example of a rare breed found only on the plains of the Marmore River in East Bolivia and used for Jaguar hunting. There is also a breed called the Pachon-Navarro, a kind of Spanish pointer which has a tendency towards this split-nose thing, and it may be that the Andean dog is descended from this strain.

 
Flash
56288.  Wed Mar 01, 2006 8:08 am Reply with quote

When we come up with something that we want the picture researchers to look into (like this one) we should post a message with the words 'picture researchers' in it, so they can search for them when they start working.

Picture Researchers.

 
Flash
56290.  Wed Mar 01, 2006 8:09 am Reply with quote

Mat adds:

Quote:
My dog's got two noses.
Two noses? How does it smell?

 
eggshaped
56298.  Wed Mar 01, 2006 8:28 am Reply with quote

I think the dog anecdote should definately be included with a MASSIVE forfeit for that joke.

 
Gray
56529.  Thu Mar 02, 2006 8:49 am Reply with quote

Flash, there's a stick thread at the top of the research forum for listing pictures in. I suggest we put all request (with a link to the appropriate posting) in there.

Meanwhile:
Quote:
German 1: My dok hess no nose.
German 2: Ja? Und how duss he schmell?
German 1: Mit einer prosthetic nasal device.
German 2: Güt.


Last edited by Gray on Thu Mar 02, 2006 12:27 pm; edited 2 times in total

 
Frederick The Monk
56588.  Thu Mar 02, 2006 11:49 am Reply with quote

More on split-nosed dogs here.

This is a 'Double Nosed Pointer':

 
Gray
56671.  Fri Mar 03, 2006 6:23 am Reply with quote

The fact that our nostrils 'wandered' as we evolved explains why cleft lips are quite common deformities in mammals. From here:
Quote:
In a human embryo, the upper jaw develops from two separate outgrowths that fuse together beneath the nose, creating a bony bridge that separates the nose from the palate and internal nostril. If this fails to happen, the result is a cleft palate. “It seems that this pattern of development contains a ‘memory’ of how our internal nostril migrated onto the palate through a gap in the upper jaw”, says Ahlberg.

You can still see the line where the two parts meet on your face - that little trench under your nose that makes it so easy to drink beer from a bottle (it lets in the air, and lets the beer out). It's called the philtrum.

Fish can smell but not breathe with their noses. We tetrapods, on the other hand, have an inner nostril or ‘choana’ that opens on the palate or in the throat.

I expect, like all things connected to scientific papers, the images will be prohibitively expensive...

 
Flash
56719.  Fri Mar 03, 2006 9:38 am Reply with quote

I like the philtrum - that's evidence for Intelligent Design, if anyone still needs it. Is there a question to be done about it under 'drinking', maybe?

 
MatC
58647.  Fri Mar 10, 2006 8:02 am Reply with quote

“Slugs have four noses” is a statement found all over the internet. The nearest I’ve found to an authoritative-sounding website making this claim is that of Women Into Science and Engineering, which you would hope would be fairly careful. Unfortunately, the same page carries the “great wall of China visible from space” factoid, which rather undermines it. Anybody know whether it’s true?

source

 
MatC
61206.  Tue Mar 21, 2006 9:42 am Reply with quote

Continuing the two nostrils theme ...

“Humans have a single larynx. Birds have a syrinx, a double wind-pipe which enables them to sing two notes simultaneously or, by alternating, 15 notes a second. Nine separate muscle movements are required to sound each note, all of them synchronised to the opening and closing of the beak. Computer-aided analysis of nightingale’s songs suggests that this hectic virtuoso activity is consciously improvised over periods of about a minute, which implies that it is music.”

Source: a 20 November 2005 Sunday Telegraph review of ‘Why birds sing: one man’s quest to solve an everyday mystery’ by David Rothenberg (Penguin 2005).

 
eggshaped
61425.  Wed Mar 22, 2006 8:56 am Reply with quote

Each of our nostrils is tuned to detect some smells better than others.

press release from Stanford

 
MatC
62412.  Wed Mar 29, 2006 6:06 am Reply with quote

“Countless working horses and donkeys in developing nations are being mutilated because of widespread superstition and ignorance. Owners believe the mutilations can cure ailments or make animals more productive – yet they are leading to widespread suffering, illness and even death.
The often-grotesque mutilations are revealed by London-based Brooke Hospital for Animals - the world’s foremost charity for the welfare of working horses and donkeys - as it launches a new fundraising campaign to help end these practices.
The Brooke runs a network of free veterinary clinics and mobile teams for working equines in Egypt, Jordan, India and Pakistan. Mutilations being seen by our vets include:
· Nostril Slitting: Many owners use a blade to slit their animals’ nostrils without anaesthetic in an attempt to widen them, mistakenly believing it will help them take in more air and increase their work capacity. Instead, this widespread practice is painful and may cause serious infection in the open wound.”
http://www.thebrooke.org/htdocs/Press-mutilations_167.php

Link to Donkeys - superstitions

 

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