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Author Topic: why Don't Reptiles Have Sticky-Outy Ears ?  (Read 7665 times)

Offline neilep

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why Don't Reptiles Have Sticky-Outy Ears ?
« on: 27/08/2008 01:37:53 »
Dearest Reptilologists,

As ewe know, my ear looks like a rabbit !

But check these reptiles out !



Unlike my ear (which looks like a rabbit by the way )

They don't have sticky-outy ears !!..why's that then ?

Why not sticky-outy ears on reptiles ?


I'm going to hold my breath until someone tells me !!



neil
Reptile Ear Asker


ps: Hurry up !!





 

Offline JnA

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why Don't Reptiles Have Sticky-Outy Ears ?
« Reply #1 on: 27/08/2008 05:18:40 »
I think it's got nothing to do with what the pinna (commonly known as the sticky out bit) does and everything to do with the way reptiles have 'evolved'.

eg there has been no need for pinnae in reptiles, so no genome exists.


that's a bit boring isn't it?
 

Offline Don_1

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why Don't Reptiles Have Sticky-Outy Ears ?
« Reply #2 on: 27/08/2008 08:47:52 »
Ok, here’s my theory: Modern day reptiles, like my two tortoises here, are low slung on their legs.



Their bodies are close to the ground and usually, when at rest, the body is settled on the ground, or as with snakes, the entire body is for the most part in contact with the ground most of the time. This would mean that most reptiles, in common with snakes, rely largely on vibration travelling through the ground and felt throughout the entire body to amplify sound. The strongest feeling of this vibration on the body, or on whichever leg, gives the direction from which the vibration is emanating. This would make a directional air vibration concentration device (the pinna) unnecessary.

As for the earlier reptiles (the dinosaurs), many of these were similarly low slung on their legs, while other much larger dinosaurs, such as Diplodocus, lived largely in water to help the legs bear the weight of these huge creatures, and water is an excellent conductor of sound waves. So again, like modern fish, sound and the direction from which it is coming, can be determined from the first point of contact with the body. For a modern example of this in a reptile, just take a look at the Crocodilians.

Another reason why dinosaurs did not develop a directional sense of hearing may well be the habitat at their time. The Earth was covered in vegetation which would have included large tree ferns etc. In such conditions, airborne sound waves would be absorbed by some of the vegetation and bounced by trunks. This would have made airborne sound waves an unreliable means of detecting direction. Ground vibration, on the other hand, I do not think is quite so vulnerable to echoes, so would be a far better means of detecting direction. The evolution of a directional airborne sound wave concentration device was therefore not simply unnecessary, but might even have proved to be so unreliable as to put the individual at risk.

Will you be breathing again now? Or will you wait for someone more knowledgeable on Herpetology to give a more rational explanation?
 

Offline neilep

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why Don't Reptiles Have Sticky-Outy Ears ?
« Reply #3 on: 27/08/2008 12:45:55 »
I think it's got nothing to do with what the pinna (commonly known as the sticky out bit) does and everything to do with the way reptiles have 'evolved'.

eg there has been no need for pinnae in reptiles, so no genome exists.


that's a bit boring isn't it?


Your posts are never *yawwwwwwwwwwwn*..boring !!  ;)
 

Offline neilep

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why Don't Reptiles Have Sticky-Outy Ears ?
« Reply #4 on: 27/08/2008 12:59:36 »
Ok, here’s my theory: Modern day reptiles, like my two tortoises here, are low slung on their legs.





Their bodies are close to the ground and usually, when at rest, the body is settled on the ground, or as with snakes, the entire body is for the most part in contact with the ground most of the time. This would mean that most reptiles, in common with snakes, rely largely on vibration travelling through the ground and felt throughout the entire body to amplify sound. The strongest feeling of this vibration on the body, or on whichever leg, gives the direction from which the vibration is emanating. This would make a directional air vibration concentration device (the pinna) unnecessary.

As for the earlier reptiles (the dinosaurs), many of these were similarly low slung on their legs, while other much larger dinosaurs, such as Diplodocus, lived largely in water to help the legs bear the weight of these huge creatures, and water is an excellent conductor of sound waves. So again, like modern fish, sound and the direction from which it is coming, can be determined from the first point of contact with the body. For a modern example of this in a reptile, just take a look at the Crocodilians.

Another reason why dinosaurs did not develop a directional sense of hearing may well be the habitat at their time. The Earth was covered in vegetation which would have included large tree ferns etc. In such conditions, airborne sound waves would be absorbed by some of the vegetation and bounced by trunks. This would have made airborne sound waves an unreliable means of detecting direction. Ground vibration, on the other hand, I do not think is quite so vulnerable to echoes, so would be a far better means of detecting direction. The evolution of a directional airborne sound wave concentration device was therefore not simply unnecessary, but might even have proved to be so unreliable as to put the individual at risk.

Will you be breathing again now? Or will you wait for someone more knowledgeable on Herpetology to give a more rational explanation?






Are ewe sure this is not the progenal offspring betwixt a tortoise and a camel ?

(great piccy...thanks)


Thank ewe Mr Don_1

Your theory sounds completely rational, plausible, credible and other words that mean ' makes sense '  to me !

As a sheepy who was asking the question I am fully convinced by your very detailed explanation and am grateful indeed for the time taken to answer my request.

Have ewe considered the olfactory senses too ?...could their sense of smell and taste be equally advanced over the need to hear ?

I know snakes, depend heavily on these senses too.


Phew !!....*lets out breath*..Thank you very much !!
« Last Edit: 27/08/2008 13:01:44 by neilep »
 

Offline RD

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why Don't Reptiles Have Sticky-Outy Ears ?
« Reply #5 on: 27/08/2008 13:58:42 »
Could be for the same reason fish don't have sticky-out-ears...

Amphibious reptiles e.g. turtles, iguanas, seasnakes, would find protruding ears a drag.

Also difficult for a tortoise to pull its head in if its ears stuck out.
« Last Edit: 27/08/2008 14:01:54 by RD »
 

Offline Don_1

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why Don't Reptiles Have Sticky-Outy Ears ?
« Reply #6 on: 27/08/2008 14:37:49 »
I don't think 'drag' would present much of a problem for a tortoise  ;D unless you are referring to a male tortoise wearing a female tortoise's shell  :D :D :D

The skin around the neck of the tortoise is very soft and supple and so would be able to cope with the head + sticky out ears being drawn in. Turtles, lizards and snakes etc. would probably not find streamlining of any real benefit. But I agree that fish and birds obviously do require such aerodynamics. But this then poses the question why do some birds (eg Eagle Owl, Long Eared Owl, Gt Horned Owl) have Pinna and the same could be asked of bats. The fact is that the pinna are shaped not only for best sound capture but also to suit the animals lifestyle. Hence if there is no need for them, they do not evolve.
 

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why Don't Reptiles Have Sticky-Outy Ears ?
« Reply #7 on: 27/08/2008 15:01:23 »
Have ewe considered the olfactory senses too ?...could their sense of smell and taste be equally advanced over the need to hear ?

I know snakes, depend heavily on these senses too.



This is,of course, quite right, and as you suggest could be another factor in the lack of pinna on reptiles. Such is the accuracy of the snakes sense of taste as it 'licks' the air that it can hunt in total darkness and 'see' with it's forked tongue and the olfactory nerves it's tongue then touches in the roof of it's mouth.

We humans cannot conceive the incredible sensitivity of the 5 senses in animals, so far beyond our senses as to make us look like deaf, blind bumbling fools.

Hmmm, I resemble that remark.... [:0]
 

Offline RD

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why Don't Reptiles Have Sticky-Outy Ears ?
« Reply #8 on: 27/08/2008 15:02:27 »
Turtles, lizards and snakes etc. would probably not find streamlining of any real benefit.

Have a look at the ears on a sealion, then tell me they have not been streamlined.
If a creature spends time in water then streamlined mutations will be beneficial, e.g. vestigial pinnae (sealion), no pinnae (seal).
« Last Edit: 27/08/2008 15:11:17 by RD »
 

Offline JnA

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why Don't Reptiles Have Sticky-Outy Ears ?
« Reply #9 on: 27/08/2008 15:08:30 »
sea creatures need the steamline for movement through the water... I don't think that applies to land reptiles.
 

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why Don't Reptiles Have Sticky-Outy Ears ?
« Reply #10 on: 27/08/2008 15:43:29 »
Quote
Have a look at the ears on a sealion, then tell me they have not been streamlined.
If a creature spends time in water then streamlined mutations will be beneficial, e.g. vestigial pinnae (sealion), no pinnae (seal).

Precisely my point, as you say Sealions have a vestigial pinnae. They are more suited to the animals lifestyle than a large, forward facing cup shaped ear would be. They are small, smooth and streamlined themselves. The drag effect of this pinna would be minimal. Also your wording is an indication as to the presence of this pinna, 'vestigial'. Perhaps at some time in it's past, the Sealion's ancestors had need of a directional listening device, which is no longer required. At some time in the next 100 or so generations, this vestigial pinnae may have disappeared altogether. Evolution at work.
 

Offline JnA

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why Don't Reptiles Have Sticky-Outy Ears ?
« Reply #11 on: 28/08/2008 03:18:09 »
Quote
Have a look at the ears on a sealion, then tell me they have not been streamlined.
If a creature spends time in water then streamlined mutations will be beneficial, e.g. vestigial pinnae (sealion), no pinnae (seal).

Precisely my point, as you say Sealions have a vestigial pinnae. They are more suited to the animals lifestyle than a large, forward facing cup shaped ear would be. They are small, smooth and streamlined themselves. The drag effect of this pinna would be minimal. Also your wording is an indication as to the presence of this pinna, 'vestigial'. Perhaps at some time in it's past, the Sealion's ancestors had need of a directional listening device, which is no longer required. At some time in the next 100 or so generations, this vestigial pinnae may have disappeared altogether. Evolution at work.


that's not exactly how evolution works. The sealion may not need the pinnae, but unless it causes some disadvantage, they will not disappear.
 

Offline Don_1

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why Don't Reptiles Have Sticky-Outy Ears ?
« Reply #12 on: 28/08/2008 08:18:11 »
Sorry, I did not make myself clear on this. My suggestion is that the Sealion's ancestors may have had the need for a directional listening device which is no longer required or the need for such a device has been superseded by the need for steamlining, so the pinnae is gradually diminshing to suit the animals best interest.
 

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why Don't Reptiles Have Sticky-Outy Ears ?
« Reply #12 on: 28/08/2008 08:18:11 »

 

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