Chameleon Tongues And How They Work. A brief explanation on the mechanics.

Goldenarcher1328

New Member
As an owner of chameleons it has fascinated me that they're tongues are used with such speed, grace and precision. After doing my research, i've decided to put up a post on what i have learned and how i see it. Feel free to pitch in more info or correct me if i have something backwards. :)

At the back of a chameleons mouth there is a "U" shaped bone called the Hyoid bone, attached at the center of this bone is a long, cartilaginous tapering horn called the Hyoid horn. A chameleon's tongue is hollow and sits sheathed over this Hyoid horn.

When a Chameleon is not taking aim at its prey, the tongue along with this mechanism is located at the bottom of the mouth, with the base seated in the throat just behind the head, as seen here http://www.chamaeleon-terraristik.de/assets/images/cSkelett8.jpg . Upon locating prey, a chameleon will "take aim" Positioning the head in such a manner that it is aligned with the prey item, the chameleon meanwhile is shifting the whole mechanism forward while muscles raise the Hyoid bone above the lower jaw bone.

At this point in time the chameleon is ready to fire.

The tongue of a chameleon is made up of three basic parts according to most people. The Tip of the tongue which is a larger, sticky pad used for "grabbing" prey items. The center of this sticky pad is tense, allowing the outer edges to flow around the prey item when contact occurs. This creates a vacuum effect, effectively suctioning the prey item to the tongue.

Next we have two types of muscles, Accelerator muscles which are responsible for propelling the tongue down along the hyoid horn and Retractor muscles which are responsible for reeling in the tongue after firing.

The muscles used to accelerate the tongue are much like sphincters. Each ring of muscle squeezes against the hyoid horn, slipping down along the tapered horn. Because the horn is tapered, the can further tighten by simply moving further down the horn, thus propelling the tongue down the horn. Ontop of this sphincter like muscle there is an elastic like collagen which is wrapped along the hyoid horn, this is attached at one end, to the hyoid horn and at the other end, to these accelerator muscles this acts as a biological "slingshot". Imagine a rubber band stretched along a pencil, at rest the elastic like collagen is like this rubber band pulled all the way back, upon releasing the rubber band, it is propelled off the tip of the pencil along with anything attached to the rubber band. Once the tongue is fired, the chameleon must simply "follow through" with the shot and wait for impact.
Chameleons will generally aim for the head of the prey to minimize the risk of a struggle. Upon retraction of the tongue the chameleon will close its eyes to prevent injury.

Retractor muscles function in a very different way, because speed is not essential to reeling in prey, you will notice that a chameleon's tongue will often collapse upon retrieval. The retracting muscles of a chameleons tongue do not act in the same ways as the accelerators, but act more like a slinky. When fully extended, the retracting muscles are smooth and in their furthest outward position. Upon retrieval, the accelerator muscles relax, allowing themselves to slip back onto the hyoid horn. At the same point in time, the fully extended Retractor muscles begin to contract and pull the tongue back into its resting position.


Now, Imagine all that in 1/16th of a second!:eek:

Enjoy!
 
im not sure exactly, but i think ivan alfonso has done some research on this. I think i saw a link, this is a guess though
 
Chris Anderson posted a very interesting topic along with a slow-motion video of the tongues in action somewhere around here...


very interesting indeed. I believe what he said in his post was that because of the difference in the acceleration vs retraction of the tongue, cold temperatures do not slow down the acceleration, but they do affect retraction rates.

interesting indeed :D
 
Chris Anderson posted a very interesting topic along with a slow-motion video of the tongues in action somewhere around here...


very interesting indeed. I believe what he said in his post was that because of the difference in the acceleration vs retraction of the tongue, cold temperatures do not slow down the acceleration, but they do affect retraction rates.

interesting indeed :D

Just read through his website and viewed the videos and it is stunning! I feel like i went to scientific heaven!!
 
Not a bad description but I've made a few corrections below just to help.

As an owner of chameleons it has fascinated me that they're tongues are used with such speed, grace and precision. After doing my research, i've decided to put up a post on what i have learned and how i see it. Feel free to pitch in more info or correct me if i have something backwards. :)

At the back of a chameleons mouth there is a "U" shaped bone called the Hyoid bone, attached at the center of this bone is a long, cartilaginous tapering horn called the Hyoid horn. A chameleon's tongue is hollow and sits sheathed over this Hyoid horn.

The entire tongue skeleton is referred to as the hypobranchial or hyoid apparatus . There are two pairs of what are referred to as "hyoid horns" in some of the old literature. One pair is comprised of the two ceratobranchial bones and the other is comprised of the two smaller ceratohyal bones. These bones meet at the base of the hyoid apparatus where another bone, called the basibranchial, is found. There is then a parallel sided forward projecting process with a tapered tip called the entoglossal process, which is what the chameleon's tongue sits sheathed over.

When a Chameleon is not taking aim at its prey, the tongue along with this mechanism is located at the bottom of the mouth, with the base seated in the throat just behind the head, as seen here http://www.chamaeleon-terraristik.de/assets/images/cSkelett8.jpg . Upon locating prey, a chameleon will "take aim" Positioning the head in such a manner that it is aligned with the prey item, the chameleon meanwhile is shifting the whole mechanism forward while muscles raise the Hyoid bone above the lower jaw bone.

At rest, the hyoid apparatus sits in the throat as you described and the ceratobrachials form an acute angle with the entoglossal process. For feeding, the hyoid apparatus is pivoted forward with the ceratobrachials now forming an obtuse angle with the entoglossal process so that the tongue is protruded from the mouth.

At this point in time the chameleon is ready to fire.

The tongue of a chameleon is made up of three basic parts according to most people. The Tip of the tongue which is a larger, sticky pad used for "grabbing" prey items. The center of this sticky pad is tense, allowing the outer edges to flow around the prey item when contact occurs. This creates a vacuum effect, effectively suctioning the prey item to the tongue.

The prehension mechanism is actually a combination of three forces. As you said, there is a suction component, but there is also wet adhesion (the tongue pad is sticky) and then as the outer edges envelop the prey like you described, mechanical grasping also occurs.

Next we have two types of muscles, Accelerator muscles which are responsible for propelling the tongue down along the hyoid horn and Retractor muscles which are responsible for reeling in the tongue after firing.

The muscles used to accelerate the tongue are much like sphincters. Each ring of muscle squeezes against the hyoid horn, slipping down along the tapered horn. Because the horn is tapered, the can further tighten by simply moving further down the horn, thus propelling the tongue down the horn. Ontop of this sphincter like muscle there is an elastic like collagen which is wrapped along the hyoid horn, this is attached at one end, to the hyoid horn and at the other end, to these accelerator muscles this acts as a biological "slingshot". Imagine a rubber band stretched along a pencil, at rest the elastic like collagen is like this rubber band pulled all the way back, upon releasing the rubber band, it is propelled off the tip of the pencil along with anything attached to the rubber band. Once the tongue is fired, the chameleon must simply "follow through" with the shot and wait for impact.
Chameleons will generally aim for the head of the prey to minimize the risk of a struggle. Upon retraction of the tongue the chameleon will close its eyes to prevent injury.

The entoglossal process is largely parallel sided with a tapered tip and the accelerator muscle is only part of the tongue, with the tongue pad being more distal. As the accelerator muscle contracts around the entoglossal process, it lengthens because it has to maintain a constant volume. As it does this, it is stretching the collagenous (elastic) elements located between the entoglossal process and the accelerator muscle (think about pulling the ends of the spring from a ball point pens away from each other). Eventually the accelerator muscle lengthens over the tapered tip of the entoglossal process, causing the tongue to shoot off, similar to squeezing a watermelon seed. When this happens, the collagenous (elastic) elements that were lengthened as the accelerator muscle lengthened are able to recoil back to their resting length (think about releasing one end of the spring from the ball point pen after pulling the ends apart), adding a considerable amount of force to the projection of the tongue.

Retractor muscles function in a very different way, because speed is not essential to reeling in prey, you will notice that a chameleon's tongue will often collapse upon retrieval. The retracting muscles of a chameleons tongue do not act in the same ways as the accelerators, but act more like a slinky. When fully extended, the retracting muscles are smooth and in their furthest outward position. Upon retrieval, the accelerator muscles relax, allowing themselves to slip back onto the hyoid horn. At the same point in time, the fully extended Retractor muscles begin to contract and pull the tongue back into its resting position.


Now, Imagine all that in 1/16th of a second!:eek:

Enjoy!

Hope that helped clarify some of it. I'm glad you all enjoy the movies on my site.

Chris
 
Dude I just read that article you just plagerized it


The original post does have a few similar phrases to the link you posted, but it all appears to be rephrased and put into his own words. While obviously no citations were given in the post, the text was not copied and pasted. You also can't necessarily tell whether this post of that page was posted first (this thread is more than 4 years old).

Chris
 
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