CHAMELEONS are a unique group of lizards. Their closest relatives are Iguanas and Dragon lizards (Agamidae). Chameleon means “Earth Lion”. Some Iguanas living in America are called FALSE CHAMELEON, due to their ability to change colours and other resembling traits. About 156 species of CHAMELEONS ARE CONCENTRATED IN Africa , Madagascar and neighbouring area. Just one species has been recorded in Europe and Indian subcontinent including Srilanka.
They are characterised by :
1.A long extendable tongue
2. Watch spring like (Prehensile) tail,
3. Protruding but independently movable eyes.
3. They have the ability to change colours depending on its moods and environment around.
The limbs of Chameleons are long and thin. This helps it to carry its body high.
Most of the chameleons are tree dwelling ones. Their forelimbs have bundled toes, with two toes on the outside and three toes on inside; their hind legs have two toes inside and three toes outside. These combinations of toes have changed each limb into a pair of clasping tongs for the chameleon to have a firm grip on its perch.
In addition to these limbs they have a PREHENSILE TAIL (Grasping tail), resembling watch spring, that helps it to balance its body weight if need be.
Africa is the home of these lizards. They are mostly found in Africa, south of Sahara , Madagascar. But the common Chameleon , Chameleon vulgaris , is an inhabitant of many eastern and Mediterranean countries. There are about 85 species in all, and each of them is remarkable in their own way. All the chameleons have the strange combination of slow moving body , a quick drawing tongue and are mostly tree dwelling lizards. They move through the twigs very slowly testing each branch before putting its weight on it. Their EYES are UNIQUE too, moving independent of right and left eyes, looking up, down, sideways, towards and behind searching for food such as insects, spiders .etc,. Most Chameleons are medium sized lizards of about 15-30 cm in length,. There are some tiny ones measuring a few centimetres. There are also giant chameleons measuring about 80 centimetres in Madagascar and Africa.
The Indian sub-continent and Sri Lanka has one species Chameleo zylanicus (Indian Chameleon).
The Chameleo zeylanicus is apple green in colour and lives among tree leaves This can change colour from green and brown to shades of yellow , white or shades of black.
Contrary to popular belief, chameleons do not change colour matching their back ground . Their colour changes are related to the surrounding temperature and moods.
Their colour is apple green in day light under normal conditions. But if you locate one using torch in the night on a tree , you will observe a fluorescent pale whitish green shade. It is easy to spot them in the night among the dark green foliage of leaves, where in they would be completely protected in the day light. Their body has pigments that can turn lighter or darker as need arises. The colour changes are related to various stimuli such as change in temperature, difference in the incident light and shadows, night and day, alarm signals, mating instinct , anger , defending mate from other rivals , etc.
Unless they increase their body temperature by absorbing heat from the sun, they stay at the same temperature as the air around them. Without warmth, they cannot hunt, move, or digest their food. In the morning they squeeze their sides together and puff out their chins, flattening their bodies to create more surface area. Dark colours absorb heat better, so the side of the chameleon facing the sun becomes almost black, while the other remains it usual colour! Chameleons are “ectotherms”, animals whose temperatures are controlled from outside their bodies.
The head has a bony casque, ornamented with crests or tubercles. A separation between the eyes, the interorbital septum, is present. Its dentition is acrodont; the teeth are compressed, triangular, and more or less distinctly tricuspid. The palate is toothless. The eyes are large, covered by a thick, granular lids pierced with a small central opening for the pupil. No tympanum or external ear is present. The body is compressed, and the neck is very short. The vertebrae are procoelian; abdominal ribs are present. The limbs are long, raising the body. The digits are arranged in bundles of two and three; in the hand, the inner bundle is formed of three, the outer of two digits; it is the reverse in the foot. The tail is prehensile. The head and body are covered with granules or tubercles.
The casque is much elevated posteriorly, with a strong curved parietal crest; the distance between the commissure of the mouth and the extremity of the casque equals or nearly equals the distance between the end of the snout and the hinder extremity of the mandible; no rostral appendages occur; a strong lateral crest, not reaching the end of the parietal crest, is present; an indication of a dermal occipital lobe is found on each side, not reaching the parietal crest. No enlarged tubercles occur on the body; a feebly serrated dorsal crest is present; a series of conical tubercles form a very distinct crest along the throat and belly. Males have a tarsal process or spur, the tail is longer than head and body. The gular-ventral crest and the commissure of the mouth are white.
From snout to vent, it is up to 7 in long, with a prehensile tail of 8 in.
They eat locusts, mantids, crickets, and other insects that hover around flowers , but larger chameleons have been known to eat small birds and other lizards.
Facts About Chameleon
1. They have long tongue having a sticky tip on the end, which serves to catch prey items that they would otherwise never be able to reach with their lack of locomotive speed.
The tip of their tongue is a bulbous ball of muscle, and as it hits its prey, it rapidly forms a small suction cup. Once the tongue sticks to a prey item, it is drawn quickly back into the mouth, where the chameleon’s strong jaws crush it and it is consumed.
2. The characteristics of changing their skin colour make them one of the famous lizard family species. Changing the skin colour is an expression of the physical and physiological condition of the lizard. The colour also plays an important part in communication between other chameleons. If they are fearful or territorial, their emotions will evoke a particular color/pattern.
3. Chameleons have teeth to grasp onto food. Their teeth are also used to help them crush and kill their food. They may chew or swallow their food whole. They can also use their teeth for tearing chunks off and then swallow. Some chameleons hold the dead prey in their mouth for several moments before swallowing it.
4. They lay eggs in a 4 to 12 inches deep hole. Some species lay 2 to 4 eggs while other species lays 80 to 100 eggs. Some species of chameleon give birth to young ones.
5. They hear vibrations in the air, which help them find food and stay safe from their enemies. They are almost deaf, but can hear tones and feel vibrations.
6. Their eyes are the most distinctive among the reptiles. The upper and lower eyelids are joined, with only a pinhole large enough for the pupil to see through. They can rotate and focus their eyes separately to observe two different objects simultaneously. It in effect gives them a full 360-degree arc of vision around their body.
7. They have zygodactyl foot, on each foot the five toes are fused into a group of two and a group of three, giving the foot a gripping and lifting like appearance. With their specialized feet, they grip tightly to narrow branches.
Chameleons can even sleep upside down!
• Besides changing colors and patterns, chameleons also “talk” to each other by flattening themselves sideways to look taller, rocking from side to side, curling and uncurling their tails and opening their mouths.
• A chameleon’s tongue launches at more than 26 body lengths per second. It accelerates from 0 to 20 feet per second in 20 milliseconds.1 At 50 g (50 times the acceleration due to gravity), the acceleration is 5 times the acceleration of a fighter jet.
• Some chameleons eat leaves in addition to the standard insect fare. Occasionally, they will launch their tongues at distant leaves and even water droplets. Perhaps in a pre-Fall world, before Adam sinned, chameleons used their tongues in the same fashion but ate only leaves. God foreknew the Fall, and His design of the chameleon’s tongue would prove to be a great asset in the post-Fall world.
• Chameleons can sharply focus on an object as little as one inch away.
• Chameleons are usually very solitary. But sometimes you will see a pair of them together or one male with several females.
• Some chameleons will dig pits or tunnels to lay two to as many as eighty eggs, depending on the species. Incubation can be as little as a month and a half to as long as two years. Eggs within a clutch usually hatch within days of each other. The offspring sometimes dig together to the surface, after which they are on their own.
• The babies of some species, especially those from mountainous environments, develop completely inside the mother’s body. Shortly after birth, they break free of the clear membrane encasing them.
• Males most often have more elaborate ornamentations (such as the presence of or a greater number of horns) and are more brightly colored than females. In some species, however, females are extremely colorful, much more so than the males.
• Most chameleons are found in sub-Saharan Africa as well as on the island country of Madagascar. Some are also found in northern Africa, southern Europe, southern India, the Middle East, Sri Lanka, and several smaller islands in the western Indian Ocean. They live in varied habitats, from rainforests to savannas and even deserts.
• Fact 1: the Weird Tongue
• Chameleons move very slowly and with great deliberation. To allow them to catch their prey they have evolved a very special tongue, which is extremely long, often it is longer than the body. The tongue can shoot out of the mouth and catch its prey with extraordinary speed, approximately 30 milliseconds (30 thousandths of a second). At the tip of the tongue there is a suction cup like structure, covered in mucus. When a chameleon sees an insect, it is very still, and captures the prey with its tongue, before the insect realizes that it is about to become dinner.
• Fact 2, its Eyes Can Move Independently
• Chameleon eyes are also unusual. The upper and lower eyelids are fused, covering most of the eye except for the pupil. The eyes are very mobile, and can swivel independently of each other. Thus giving them almost 360o degree vision and allowing to focus on 2 objects at once. This allows the chameleon to search for food in its vicinity very effectively. When an insect is spotted, it can focus on it with both eyes, so it can judge distance and extend its tongue out with great accuracy.
• Pincer like feet
• Chameleon foot anatomy is also unlike that of other lizards, and is perfectly adapted to grasping branches and twigs. The toes on each foot are partially fused into two groups, one consisting of 2 toes while the other has 3. This makes chameleons didactyl and gives their feet a pincer-like appearance, allowing them to grasp objects. On the front feet the 2 toed group is on the outside, while the 3 toed group is on the inside, and on the back feet this order is reversed. Each toe ends in a sharp claw which allows helps with climbing tree bark.
This type of long legs leads to their slow movement in flat surface like road and are not meant for running.
Hence they are susceptible to be run over by vehicles unless we have humane DRIVERS WHO LET THEM PASS.
ELSE THEY DIE AS SEEN BELOW
Changing Colour for Social Interactions
Many lizards can change colour to a certain extent, but chameleons can do this to a remarkable degree. Although this aides camouflage, the main purpose is communication with other lizards, either warning off rivals, or attracting females.
Chameleons are solitary and very territorial animals, males do not tolerate other males in their territory, and will colour up to warn them off. They generally turn dark when they are angry. Changing colour also helps them thermoregulate, they become darker when cold, to absorb more sunshine, and paler when they are too hot.
Chameleons can alter their colour rapidly because their skins contain three types of pigment cells arranged in three layers. The top layer consists of xanthophores, and erythrophores, which contain yellow pigment. The layer below that consists of cells called iridophores which appear white or blue. Below that are the melanophores, containing melanin which is black. The distribution of the pigment granules in the cytoplasm of each type of cell is controlled by the nervous system and controls the appearance of the skin, when the pigment granules are distributed evenly thoughout the cell, it appears intensely coloured, whereas when the pigment is concentrated in a tight spot in the centre, the cell becomes almost transparent. Hence the chameleon can have different patterns, which can rapidly change depending on its mood.
In the night they mostly sleep on the tree with its florescent green colour or breeding time colour.
Article by Mr. R Venkata Ramanan. Chennai based educational consultant. See linkedIn profile.
R Venkata Ramanan
Padmini V Ramanan Educational Resource Centre
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