How does a Chameleons tongue work ?

Panther Chameleon tongue
A
ll chameleons are predominantly insectivores.  There are  however many Chameleons will actively eat fruit, plant leaves and other vegetation as part of their diet.

With a speed of 13.4 miles per hour (Bijal P. Trivedi, “Catapults” Give Chameleon Tongues Superspeed, Study Saysthat can surpass even some of the fastest bikers in the world with ease, the tongue features a sticky substance that makes hunting or preying times easy and deadly. Modern research suggests that the reason behind a Chameleon’s ability to throw the tongue with ultra-fast speed lies primarily in its biological structure.

That is, structurally, like a motion that resembles arrow launch from a bow, the tongue is propelled by elastic collagen tissue structured in the middle of accelerator muscle and tongue bone or hyoid bone, acting as a catapult.

 The speed at which the Chameleon shoots its tongue is not the only striking thing about the Chameleon’s tongue. Interestingly, a Chameleon has the ability to project its tongue to a distance close to one and half times its body length. Even more surprising is the fact that certain less-researched smaller variants of the lizard can throw their tongues to distances as long as twice their body length!

A Chameleon can typically shoot its tongue out reaching its target in as little as 0.007 seconds. (Chameleon, Wikipedia).
Closely resembling a club (Tongue Mechanics, reptilis.net), the tip of a Chameleon’s tongue contains saliva of sticky  nature, which help adhere the front part of the tongue to the prey in target, when a strike is performed by the lizard. Coiled inside the mouth neatly when not in use (The Incredible Projectile Tongue of the Chameleon, Scribol), the tongue works with the help of circular as well as longitudinal muscles. When it comes to pulling the tongue back in its place, the retractor muscle known as hyoglossus shows its magic of following the tongue projection with precision and accuracy.

Almost every single aspect about the Chameleon’s tongue is extremely interesting especially its ability to project its tongue with such high speeds even when its body temperature remains considerably low, which is not the case with other similar ectothermic animals.

 

References:

1) Trivedi, Bijal. “Catapults Give Chameleon Tongues Superspeed, Study Says.” National Geographic News. National Geographic Society, 19 May, 2004.Web
2) “Chameleon.” 
Wikipedia. Wikimedia Foundation, Inc., 26 April, 2014. Web.
3) “Tongue Mechanics.” 
Reptilis. Reptilis. Web.
4)  Sarus, Emmy. “The Incredible Projectile Tongue of the Chameleon.” 
Scribol. Scribol, 11 October 2010. Web.

 Images:

1) Main image supplied by Scott Cromwell

Chameleons Eyes

How do Chameleons eyes work

Another surprising fact about Chameleons are the uniqueness of structure and ability of its eyes.  Chameleons have eyes that move and view independently of each other.   That is to say that the creature can move one eye to one direction, and the other eye to a totally different direction at the same time.  This kind of ability provides it with approximately 360-degree vision (Ask Nature).  

The eyes of the Chameleons are actually made up from one large cone shaped eye lid.   It covers virtually the whole eye, leaving a tiny hole to expose the pupil.   Having an eyelid for protection of the pupils, the Chameleon can watch a predator coming its way, and at the same time, examine its surroundings for the best escape routes.   Being one of the most visually-oriented lizards (Chameleon vision, Wikipedia), the creature primarily utilizes its eye-abilities during predator avoidance and prey capture.

One of the primary striking features of the Chameleon eye is the presence of the negative lens.  However, note that although the lens is negative or concave, the cornea is actually positive.  The combination of both gives this creature an unparalleled eye sight.  In fact, the Chameleon eyes are considered to have the highest image magnification among many other vertebrate’s eyes.  Their eyes focus extremely quickly, effectively zooming in on their prey for a much better look and due to the shape of the lens in their eyes, Chameleons can see a large and clear image and this obviously helps when targeting its next meal.  When the Chameleon spots a cricket, locust or meal worm (which can be as much as 10 meters away) it turns its head to face the prey.   The Chameleon will then point both eyes directly at the target, switching to stereoscopic or binocular vision.   The Chameleon uses its binocular vision to increase depth perception and helps the Chameleon to aim with pin point accuracy.

Further to this, Chameleons are known to see in the ultraviolet range too (Devi Stuart-Fox, University of Melbourne), an ability that is quite unique in the animal world! Having lived in the world for more than 80 million years (Chameleons, NWF), the creature has always been an interesting topic among scientists.  Moreover, studies find that Chameleons have the ability to switch between synchronous and uncoupled saccadic eye movements.  That is something totally unique, and not witnessed in case of any other vertebrate in the world.

 

References:

1) “EYES GIVE 360˚ VISION: CHAMELEON.” Ask Nature.  Ask Nature.  Web.  1 May 2014
2) “Chameleon vision.” 
Wikipedia.  Wikimedia Foundation, Inc., 20 April 2014.  Web.  1 May 2014.
3) MacKenzie, Debora.  “Chameleons’ colourful flashes are social signals.” 
New Scientist Reed Business Information Ltd. 29 January 2008.  Web.  1 May 2014.
4) Bishop, Gerry.  “Chameleons.” NWF.  National Wildlife Federation.  Web.  1 May 2014.

Images:

1) Main image supplied by Scott Cromwell

How do Chameleons change colour ?

Parsons Chameleon

 Although many people have a misconception that the Chameleons change of skin colour is targeted toward blending with the surroundings, that is not strictly true.  The main reasons for skin colour change include mating behaviour, emotion exhibition and temperature adjustment.  For instance, if a male Chameleon tries to attract females, it may exhibit lighter and brighter skin colours.  On the other hand, since Chameleons do not possess the ability to maintain body heat, the lizard can achieve optimal temperature with the help of darker shades to absorb heat, and lighter shades to release heat (Bates, 2014).  The range of colours is enormous, including blues, reds, greys, pinks, yellows, purples and more.  However most species of Chameleons can only change between a limited numbers of colours (Raxworthy, 2014).

For example most Veiled Chameleons will change colours mainly using greens, yellows and dark greys or black. Going back to the point about whether or not Chameleons can change colour to match their surroundings, we did find a study from the New Scientist that shows some species of chameleons like the Smith’s Dwarf Chameleon can actually change their colours to almost match their surroundings when under threat from different species. In particular birds and snakes.
www.newscientist.com/article/dn13944-chameleons-finetune-camouflage-to-predators-vision.html#.UfEwGY21GBQ

How does the Chameleon change its colours ?

On a physical level, colour changes in Chameleons involves skin cells. Chameleons have outer skin that is transparent, and there exist a number of skin layers having special cells known as chromatophores. When signals are received, these cells expand and contract.  Since these cells contain colour pigments, expansion and contraction results in different skin colours (Clark, 2005).  For instance, if red cells become fully expanded, then the skin colour of the Chameleon appears to be red.  On the other hand, when green cells seem to expand, a Chameleon appears to be green.

 

References:

1) Bates, Mary.  “How Do Chameleons Change Colours?” Wired.  Howard S.  Mittman, 11 April 2014.  Web
2) Clark, Rulon.  “How do chameleons/anoles change colours?” 
Cornell Center for Materials Research (CCMR).  Cornell University, 27 January 2005.  Web
3) Raxworthy, Christopher.  “A Truly Bizarre Lizard.” 
PBS.  Public Broadcasting Service.  Web

Images:

1) Main image supplied by Dan Fegent

Chameleons Tail

Panther chameleon
Most Chameleons have prehensile tail, which basically means that the tail allows the creature to hold onto branches and move from one branch to another, in order to make its life easier when it is above the ground.  In fact, the meaning of “prehensile” is ‘able to grasp’ (Prehensile tail, Wikipedia).

The length of a tail depends mostly on the species and age of the Chameleon in question.  For instance, a 9 month old Veiled Chameleon could possibly have a tail of approximately 7-inch in length, where as a 9 month old Pygmy Dwarf Chameleons tail would be considerably smaller.

Since the creature has prehensile tail, the tail cannot fall off and then re-grow, which happens with a number of other similar lizards (Chameleon, San Diego Zoo).  In other words, a Chameleon cannot drop its tail.  Many people are also of the opinion that the tail is used for balancing purposes, and it makes sense to a certain extent.  

As far as colour of tail is concerned, it depends on the Chameleon.  Moreover, since the creature is able to change its skin colour based on temperature, light and mood, the tail colour changes to suit.

We have noticed that when a Chameleon is about to go to sleep, it curls its tail, whether this is to make the Chameleon appear smaller and compact keeping it better hidden or it could be simply that it’s the most comfortable position for the Chameleon to sleep in, we are not sure.

 

References:

1) “Prehensile tail.” Wikipedia.  Wikimedia Foundation, Inc., 26 December 2013.  Web.
2) “Chameleon.” San Diego Zoo Animals.  San Diego Zoo Global.  Web.

Images:

1) Main image supplied by Cow Yeow

Chameleons Feet - Image supplied by Etai Adam

Chameleons Feet

Chameleons feet are highly adaptive to different situations with their sharp claws and powerful grip.   On the front foot of the Chameleon the outer group of digits contains three toes, and the inner group contains two.  However, when it comes to rear feet, the arrangement gets reversed completely.  Due to the unique structure of their feet, Chameleons can easily grip narrow tree branches, vines, twigs and rough surfaces.  In addition to that, since its feet feature special claws too, holding on to bark during climbing is not a problem for the creature either.  It is worth taking note that no other animal is known to have feet like that of Chameleon till now (Chameleons, NWF).  
One thing to keep in mind is that their claws do get very sharp, they will shred the leaves of any plant you place in their enclosure and they will make a mess of your hands.  You may be tempted to clip or trim the Chameleons nails or claws, don’t.  They are arboreal and need those sharp claws to climb.

You will often find your Chameleon hanging in some very strange positions, we have observed several Chameleons who seem to enjoy simply hanging upside down and it’s those sharp claws that are keeping them from falling.

It is also noted that although a number of, scientists sometimes describe Chameleon feet as “zygodactyl” or “didactyl”, none of these two terms truly apply in case of Chameleons (Chameleon, Wikipedia).  The main reason why the first term is misleading is because the term was first coined to describe parrot foot, and although Chameleon’s feet resemble that of parrot slightly, the structures are not totally identical.  Moreover, when it comes to the other term “didactyl”, since the term only applies in case of creatures having two toes on each foot, the Chameleon does not fit the description since each of its feet contains five toes.  However, when it comes down to appearance only, the Chameleon’s foot does look a bit like a set of tongs or pincers, and that is because the toes remain in groups of two or three.  The structure can be loosely described as “split into two main fingers” (Chameleons, Sheppard Software).

References:

1) Bishop, Gerry.  “Chameleons.” NWF.  National Wildlife Federation.  Web
2) “Chameleon.” Wikipedia.  Wikimedia Foundation, Inc., 26 April 2014.  Web.
3) “Chameleons.” Sheppard Software.  Sheppard Software.  Web.   

Images:

1) Main image supplied by Etai Adam