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Tonights repeat of Qi 05/01/05

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12992.  Wed Jan 05, 2005 5:25 pm Reply with quote

Am I hearing things or did a certain tall personage just claim snakes don't have ears?
That is incorrect. Or am deaf and he never said it
They do have ears they are internal.

12994.  Wed Jan 05, 2005 5:32 pm Reply with quote

Well, tell them then!! I thought that.

they have a comments bit, I'm sure you know this, but just incase.

It's a good thing we noticed!! Do you know when it's on again?

12998.  Wed Jan 05, 2005 6:41 pm Reply with quote

'Ears' are external organs that receive air pressure variations (or 'sound', as we call it) and pass the signal to the cochlea which picks out the frequencies in it. As snakes have no exterior orifices (unlike lizards), they can't strictly be said to have ears.

They do, however, pick up vibrations from the ground by pressing their jaw bones against a stone or hard earth. The sound waves travel up their jaws and into the hearing centres of the inner ear, and thence into the brain. So they still have the internal ear structure, but not 'ears' as such.

This sense is used as a part of their ambush tactic, so that they can hear rodents approaching across the ground, and is also used to detect potential predators. This is why you will hardly ever see snakes - they will hear your elephant-like footsteps and hide a long time before you see them.

Interestingly, the bones in our middle ears (incus, malleus and stapes) were originally part of our jawbone, way back in evolutionary history.

13001.  Wed Jan 05, 2005 6:51 pm Reply with quote

I hesitate to disagree with you as Flash has suggested that you are somewhat of a zoology expert amongst other things
But I think it depends on your definition of an ear.
Certainly it is internal this I have stated. And yes it is primitive, they have to my knowledge no ear drum.
They can only hear low frequency sounds however
I'll find some links

13002.  Wed Jan 05, 2005 7:04 pm Reply with quote

I can't find the link I'm looking for but this backs up what I'm saying ish
You see my issue with the old vibrations through the jaw only theory is it would surely suggest that they cannot hear airborne sounds. Yes/NO?
But the evidence is the can process airborne sounds.

13009.  Wed Jan 05, 2005 8:51 pm Reply with quote

Actually, it's Alan who says "they don't have ears". Stephen replies:
You're sort of right, until recently that was exactly what was thought, because they don't appear to have any, but in fact when you go inside, they've now discovered, they do have otic nerves and a whole system which responds electrically to sound.

So that's all right, then.

13010.  Wed Jan 05, 2005 8:56 pm Reply with quote

Um don't yell,
I know I always disagree but I think that was in a different episode the one about snake charming or have I just lost it entirely.

13012.  Wed Jan 05, 2005 9:10 pm Reply with quote

I'm quoting from the 2nd series music special, the one with Sean Lock, Mark Gatiss and Linda Smith, first broadcast on BBC2 the week before Christmas. Are we talking about a different one?

13014.  Wed Jan 05, 2005 9:21 pm Reply with quote

yes we are talking dave Gorman Jo Brand and jeremy harding

13019.  Wed Jan 05, 2005 9:41 pm Reply with quote

Oh, OK, first series. Nothing to do with me.

13021.  Wed Jan 05, 2005 9:47 pm Reply with quote

Oh so the jolty editing wasn't you then
Fair enough
Damn brilliant show regardless, always is
Last series we had was the absolute bees knees though.

13033.  Thu Jan 06, 2005 7:35 am Reply with quote

Well, I sit very much corrected! I just believed what they told me in the zoo, where I worked with snakes for a while. It just shows - never hesitate to disagree - it's one of the only ways we have of learning anything! :-)

I was aware that they could process low-frequency sounds, in much the same way as you can 'feel' the bass through your skull if it's loud enough, but this doesn't really rely on ears.

I'm slightly suspicious in that I've not heard of this research before, and nothing else I've read on herps mentions it (which you might think would be the case if it was done in the 1970s), but it seems reasonable. Have you found any other references that agree with their findings. Not that I doubt them, but am just surprised that no other 'authorities' mention this as far as I've found in the past. goes into some mechanics as well, which is QI.

13042.  Thu Jan 06, 2005 11:08 am Reply with quote

I do hope the repeats of the first series will become a regular thing, I very much enjoyed last night's episode and I am even now furious with myself for missing the entire first series and some of the second.

13046.  Thu Jan 06, 2005 11:26 am Reply with quote

Gray - here's some stuff I found when researching the question for series 2. I'm no expert, though:
A few decades ago the answer (to the question "can snakes hear?" - F) was no, for - obviously - snakes don't have external ears. And any way, snakes don't appear to respond to loud noises. Further support for this view is found in some current zoology texts, which still report that snakes lack the sense of hearing. But research begun about 35 years ago, especially the extensive investigations over many years by E.G. Wever and associates at Princeton University, has shown that snakes have a hearing capability(at least in an electrophysiological sense) comparable to that of lizards.

This should not be too surprising, for snakes and lizards share some common features and are thought to have common ancestors.

So how can a snake hear, lacking external ears? By having equivalent structures on each side of its head. The skin and muscle tissue on each side of the head cover a loosely suspended bone, called the quadrate, which undergoes small displacements in response to airborne sound. The quadrate motion is transferred by intermediate structures to the cochlea, which produces electrical signals on its hair cells that correlate with the airborne sounds (within a range of intensity and frequency determined by the ear system) and are transferred to the brain.

Cochlear signals are present in functioning ears of all classes of vertebrates from fish to mammals, while animals that are congenitally deaf produce no such signals, so their presence in response to sound is taken as an indication of the hearing sense. Wever and co-workers [1] developed techniques to measure the hair-cell signals in lizards, snakes, and amphibians, which involved anesthetizing the specimen, inserting a very thin wire probe into contact with a hair cell, and measuring the acoustic signal level needed to produce a specified hair-cell signal (typically 0.1 microvolt). Various experiments were performed to demonstrate that the hair-cell signals were in direct response to airborne sound and not to mechanical vibrations from the medium on which the specimens were placed.

According to Porter [2], the auditory response of snakes in the range of 200 to 300 Hz is superior to that of cats. Hartline and Campbell [3] investigated the transmission of airborne sound through the snake's skin and lung into the inner ear. Wever's results show that this type of transmission, called the somatic mode, is much reduced compared to that through the skin to the quadrate, which is the main mode of hearing.

How are the cochlear responses to be interpreted? Wever points out that it is often difficult to determine the role of hearing in lower forms such as reptiles. It is possible that snakes make less use of the auditory sense than other animals. He notes that the maximum sensitivity occurs in the frequency range of noise made by movements of large animals, so detection of such sounds could function as a warning to snakes to be motionless, a common defensive action with animals. (Although not discussed in the references I was able to check, there is also the question of how the cochlear signals are used in the snake brain. Is it possible that the ability to process this information has been or is being lost?)

As most people should know by now (from various documentaries, books and who knows how many TV specials) snakes lack external ears. This is sometimes misinterpreted as having no ears, which is false. Snakes do have ears, inner ears that allow them to hear low frequency airborne vibrations. But snakes have another more acute way of hearing, they hear with their jaw.

Strange as it might sound, it is true. Ground vibrations are transmitted through the snakes body to the quadrate bone (the connection between the lower jaw and skull) where it later goes the middle ear bone (columella) and then to the inner ear.

This means that a snake will always hear you coming before you even see it.
The hearing in snakes and some lizards is not as we understand it. They do not have an external ear opening. They are not deaf, just lack the ability to detect high frequencies of sound conveyed through the air. They do hear or more correctly feel low frequencies, and have a tremendous ability to detect the most subtle of vibrations transmitted through sand, leaflitter, dried grasses and to a lesser degree hard ground.

13048.  Thu Jan 06, 2005 11:34 am Reply with quote

what's happening with the repeats? I mean am I going to need to update my sie already? if so any series one info would be welcomed.


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