Chameleons: Amazing Lizards

Meller’s Chameleon, the largest lizard from continental Africa (there are large chameleons in Madagascar).

Chameleons are extraordinary lizards. These arboreal insectivores (tree-living insect eating animals) are also fairly familiar lizards, that appear as pets, in movies, shows, and books, plus they are famous for a couple of traits. It turns out, however, that chameleons are far more unique and interesting than most people think.

To begin, let us briefly consider what a typical lizard body looks like. You should all be familiar with this form: a long body; tapering head; long, tapering tail; four legs with the back two being longer than the front; and so forth. Here are a few more pertinent details: a lizard typically has five toes on each foot. The toes, while they have different length, all splay outward from the foot. A lizard has a sprawling posture, meaning that its legs, especially the hind legs, stick out to the sides, which is quite different from our legs which are held directly under our bodies. As I said, a typical lizard is pretty familiar, so you can probably easily imagine what one of these creatures looks like.

Now let us turn out attention back to a chameleon. What makes them unique? The first thing that comes to mind is probably, “They can change color.” Yes, indeed chameleons can change their colors. However, changing color is not quite as special as it may seem. First of all, while chameleons can change their colors to suit their surroundings, they cannot turn “invisible” by perfectly matching their backgrounds. The creatures that can change their colors to perfectly match their backgrounds are cephalopods, like octopuses and cuttlefish. Also, while chameleons can change their color to suit their surroundings, that is not its primary purpose. Instead, they usually change color for communication or in response to temperature. A chameleon can change color as a threat display, to show it is angry, frightened, or other reasons. They also change color based on temperature, which can help with absorbing more sunlight if they need to warm up, and so forth. Finally, chameleons are not the only lizards that can change colors. The anoles (which are sometimes called American chameleons) can change color as well, though they may not change as vividly or rabidly as chameleons. In fact, many lizards can, to a degree, change their color, so while chameleons may be the best at changing color among the lizards, they are certainly not the only ones.

Another trait that is special among chameleons is their independently moving eyes. Like color changing, many lizards can move their eyes independently, to a degree, but chameleons are by far the best at it. Most mammals and humans have eyes that are neurologically connected such that they both move together. Try moving one eye without moving the other. It is nearly impossible to do because your brain is hardwired to keep both eyes looking at the same object. The best we can do is cross our eyes, but even then, our eyes typically move together toward the middle, rather than moving independently. Chameleons, however, have eyes that are not so connected. This means that a chameleon can set each eye looking at a different object and view both of them at once. Technically, they do not see two things at once. Rather, they switch which eye they view out of each second, meaning that they get a glimpse out of one eye, a glimpse out of the other, then a glimpse out of the first eye again, and so forth. That allows a chameleon to scan in two different directions as it hunts for its prey. Once an insect has been selected and targeted, a chameleon can then swivel both eyes to point in the same direction. Why would it need to do this? Because with both eyes pointed in the same direction, it can now have binocular vision and more accurately judge distances. The same thing is true for us. We can easily throw a ball at a target and either his it or get close to it. Go ahead and try it. Now, do the same thing, but this time, close one eye. It is much harder, isn’t it? Two eyes focused on one object gives two, slightly different perspectives on the same thing, which our brains can interpret as distance. The same is true for a chameleon, so when it needs to judge distances, both eyes look at the same thing.

Why would a chameleon need to accurately judge distances? Because it can shoot its tongue out to catch insects. The tongue of a chameleon is very special. There is a bony base to the tongue which is shaped much like a long gone. This bony base, called the hyoid bone, sits in the throat of the chameleon and the tip of the cone points toward the mouth. Wrapped around this cone are layers of muscle that are all bunched up together. Imagine taking the sleeve of your shirt and bunching it up by your shoulder. Now imagine that the sleeve was a sheet of muscle. What would happen if it were to contract? It would squeeze on your arm. Now imagine this same muscle were sitting on the wide end of a long cone. Now what would happen when the muscle contracts? It would slide toward the tip of the cone. The same thing happens in a chameleon’s tongue, only it contracts so quickly that its shoots right off of the bony base. The tongue then flies forward until it strikes its target. The tip of the tongue is sticky and it has flaps that can wrap around and grasp its prey. The tongue of a chameleon is so fast and its aim so accurate that they can actually snag flying insects right out of the air! Once the insect has been snagged, the chameleon then drags its tongue back into its mouth to eat.

Living in trees and hunting insects means that chameleons require a special body shape. While most lizards have bodies that are cylindrical or flat from top to bottom, chameleon bodies are flat from side to side. Their narrow bodies allow them to crawl along the tops of thin branches and twigs without losing their balance. They also have grasping feet. Remember that most lizard have splayed feet. In contrast, chameleons have three toes that are bound together as a single unit and the other two toes are bound together as a separate unit. Each bundle of toes stick out on opposite sides of the foot so that they can grasp branches and twigs. Imagine that rather than a single thumb, you had two thumbs and three fingers. Now imagine that these thumbs were bound together in one piece of skin your other fingers were also bound in a single piece of skin. Your hand would look a bit like a mitten with a large, flat thumb. This is what the forefeet of chameleons are like. The hind feet are very similar, but the two toes are on the outside rather than on the inside (the “thumb” is on the outside of the foot, rather than on the inside). These toes give the chameleon a strong, sturdy grip, making them excellent at crawling along the top side of branches and twigs. In fact, chameleons are so specialized for climbing in trees that they are quite awkward on the ground.

There are two more interesting aspects about the body of chameleons. First, since they climb along the top side of branches, they hold their legs under the bodies most of the time. This is in stark contrast to typical lizards that have sprawling legs. In addition, the tail of most chameleons is prehensile, meaning that it is flexible and capable of wrapping itself around twigs and branches. The tail then acts kind of like a fifth limb, giving the chameleon one more point it can use to hold onto a tree.

Chameleons are amazing lizards. While they are famous for their ability to change colors, there is so much more about them that is unique, from their independent eyes, to their extendable tongues, to their grasping feet, flat bodies, legs held under the body, and prehensile tails. Everything about these lizards is designed for a life as arboreal insectivores. Praise God for the diversity and design of the amazing creatures that He created.

Thoughts from Steven

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