Colours of Wildllife: The Flap-Necked Chameleon
Created | Updated Apr 1, 2012
Willem is a wildlife artist based in South Africa. He says "My aim is simply to express the beauty and wonder that is in Nature, and to heighten people's appreciation of plants, animals and the wilderness. Not everything I paint is African! Though I've never been there, I'm also fascinated by Asia and I've done paintings of Asian rhinos and birds as well. I may in future do some of European, Australian and American species too. I'm fascinated by wild things from all over the world! I mainly paint in watercolours ... but actually many media including 'digital' paintings with the computer!"
The Flap-Necked Chameleon
Today's picture is of a Flap-necked Chameleon, Chamaeleo dilepis. This acrylic painting was done from one of my own photos, of a large chameleon that had entered our garden. It is perching on a Spike-thorn tree, Gymnosporia senegalensis. This one was between ten and twelve inches in total length, in my estimation.
Chameleons fascinate me without limit! My experience of them go back to my early childhood. In Queenswood, Pretoria, where we lived, there were still patches of undisturbed 'veld' in between the residential areas, including a patch next to the Kindergarten I attended. Once, I – or maybe my dad – found a nice big chameleon there, and we kept it a while before releasing it again. We named it 'Kleure' (Colours) and kept it in a bird cage; we fed insects to it, holding them up to the bars, and it would catch them with his long, sticky tongue! It grew rather fat in the short while that we kept it.
From then on, I've encountered a great many chameleons here in South Africa. It's a thrill even seeing one in the bush – they are not easy to see, so it's a kind of an accomplishment to be proud of! The Flap-necked Chameleon is the main one we have here. Other species in the country include a great variety of Dwarf Chameleons, and the remarkable Desert Chameleon, Chamaeleo namaquensis.
There is almost not a single piece of a chameleon's body that is *not* very, very weird and unique. Let's start at the rear. Most chameleon species have a strong, muscular, prehensile tail that they can firmly curl around twigs or leaves while they're clambering around, 'anchoring' them in case their hands or feet should slip. When the tail is not being actively used in climbing, it is usually tightly coiled. While other lizards – skinks, for example – can shed their tails when a predator grabs them, and then re-grow it, chameleons can't do this – the tail is much too intricate and vital to them.
A minority of chameleon species have short, non-prehensile tails. In the Desert Chameleon, the tail can still be coiled a bit, but is much shorter and less dexterous than those of the forest-and-thicket-living species. But in the ground and leaf chameleons of the genera Rampholeon, Rieppeleon (in Africa) and Brookesia (in Madagascar), the tail is very short and stubby, in some of them resembling the stem of a dry leaf (while the body resembles the leaf blade itself).
The body of chameleons is different in shape from that of most other lizards. Instead of being cylindrical or flattened from top to bottom, chameleon bodies are tall and flattened from side to side. Indeed, most chameleons resemble leaves in general shape – which certainly offers some advantage in camouflage. When a chameleon is threatened, however, it can blow up its body with air to look much bigger.
Along the upper surface of the back, most chameleons have a ridge, which in many species has been elaborated by a row of pointy growths making it look much like the back of a traditionally-conceived dragon.
Chameleon limbs are highly specialized. In gait, they differ from pretty much all other living lizards, in not having their limbs sprawling to the sides, but held fairly upright below the body. This is because they mostly 'walk' along twigs, with their feet right below them, and the body held high above the twig. When walking on the ground, a chameleon will still use the same gait, body held high and feet lining up beneath it.
The 'hands' and feet of chameleons are wonderfully adapted! They have been shaped into pincers or 'graspers'. Two fingers or toes oppose the other three – imagine a human hand with *two* thumbs, and three fingers, and you have the idea. But in the chameleon, the 'thumbs' are fused together, with only the tips and the claws separate – and the same thing goes for the 'fingers', all three also being fused together, with just the three claws at the tips showing that actually they're three digits. Thus the 'hands' look like clasping 'mitts', with only two functional opposable digits. The skin on the 'palms' are rough; this along with the claws prevent slippage. The feet are the same as the hands – so chameleons can grasp with all four limbs.
The usual manner of chameleon locomotion is very slow and deliberate. This gives them their Afrikaans name 'Trapsuutjies' (tread softly). In addition, they usually employ a forward/backward swaying motion as they move along. This is probably to disguise their deliberate forward motion, making them look more like leaves randomly swaying in the wind. Although chameleons usually move slowly, they can put on bursts of speed when necessary – but even so, they are not nearly as fast as 'regular' lizards and skinks. They rely on disguise and bluff, rather than on speed, for escaping predation.
Chameleons encountered in the bush can be caught with relative ease. They will puff up, hiss, turn black, and may try to bite, but might also soon 'relax' and – despite the seemingly highly affronted scowls on their faces – perch placidly on your hand, or clamber from finger to finger – you can keep them climbing from hand to hand for a long time, and see and feel just how wonderfully those little graspers (not to mention the prehensile tail) of theirs work.
Chameleon heads contain the majority of specializations. In general shape, the head is usually somewhat triangular in profile – tall at the back tapering to the snout. Most chameleons have a crest at the rear of the skull – in some species like the Yemen Chameleon, Chamaeleo calyptratus (the male), this crest is very tall, almost as big as the rest of the skull, and can be raised high. In many species, the crest has bumps or growths on it, or flaps of skin at its sides. The Flap-necked Chameleon is named for the flap of skin at the back of the head crest that extends over the sides of its neck.
The top and front of the skull may also be 'decorated' with tubercles, horns or weirdly shaped growths. In Jackson's Chameleon, Chamaeleo (Trioceros) jacksonii, there are three long, forward-pointed horns – two over the eyes, and one on the snout. Other species have different configurations of horns and growths. But many species don't have these elaborate structures. There may be a difference between the sexes within a species, with females having smaller or no head growths.
Below the skull, most chameleons also have a crest along the midline of the throat. There is a pouch below the lower jaw that can be inflated to lower or raise this crest. The skin along the throat is grooved lengthwise to allow expansion as the crest is raised. This is a display feature – a threatened chameleon will extend its throat as it puffs itself up, to contribute to making it look bigger. At the same time, the skin inside the throat grooves – which in most species is brightly coloured – will be exposed. This throat-expansion is also used by males displaying to each other to settle disputes over territory or females.
Then there are the eyes! In chameleons, the eyelids have fused together, covering the entire outside of the eye, leaving just a small hole for the pupil to see through. These eyes can be swiveled around like turrets – and independently of each other! The one eye can be looking forward, while the other is looking to the side – or backward, or upward, or downward. The eyes protrude very far from the skull, with just those extended eyelids keeping them in place, and thus have great freedom of movement – so that the chameleon generally doesn't need to move its skull at all, if it wishes to look in a particular direction. There must be something special going on in its brain as well, so that it can independently assess the fields of vision it gets from each of its eyes.
But when a chameleon spots potential prey, it turns its head towards it, and then focus with both eyes on it at the same time – giving it binocular vision, just like ours. It can estimate the distance to the prey, and then shoots out its tongue to grab it.
And now we come to that tongue! It is one of the most amazing structures in the animal kingdom. Chameleon tongues can be shot out to – in some cases – a length equal to that of the body and tail combined. The tongue has a large, muscular, sticky tip, almost like yet another 'hand' with which prey can be grabbed.
The way the tongue works is that there's a bone inside it, at its base. This bone can be flicked forward very rapidly, impelling the main muscle mass of the tongue forward as well. If all goes as planned, the tip grasps the tasty morsel, and then with the retractor muscles the chameleon draws the tongue, and the food, back into its mouth.
I've saved the best adaptation for last: the ability to change colour! Chameleons have special colour cells called chromatophores in their skins. The outer layer of skin is actually transparent, with the chromatophores lying beneath it. They, too, are grouped in layers, with the layer above containing red or yellow pigments, and lower layers being able to reflect blue light, or to lighten or darken the colour. Yellow pigments over the blue layer, for instance, will give a green colour. The pigment in the cells can be manipulated: if it is spread throughout the cell, the whole cell will reflect light of that colour, but when it is all drawn into the centre of the cell, the cell will appear transparent. So, the different chromatophore can either reflect, or let through, light of different wavelengths – i. e. colours.
Every chameleon has an intricate and characteristic pattern of colour cells on its skin, with different kinds of pigments in them. These patterns to some degree constrain its colour-change ability. In reality, chameleons cannot take on any colour or pattern – they can only change their colour according to what particular pigment cells they have, and their pattern will always depend on the arrangement of these cells. Nevertheless, many species have a great range of possible colours and patterns. The Flap-necked Chameleon is under ordinary conditions yellowish, greenish, or brownish. When threatened, it turns dark brown – almost black. At night, it turns very pale grey, almost white. It can also be unicoloured, or display patterns of spots, bars or stripes along its sides. Chameleons can even have different colours and patterns along different sides of the body.
It is true that generally chameleons use their colour-changing ability for camouflage, but it is not quite as expert at this as most people think. It cannot perfectly mimic colours and patterns of its environment; more typically it takes on a greenish, grayish or brownish mottled appearance that will make it generally hard to spot against a background of leaves and bark.
Colour change may also help with temperature regulation: dark colours absorb heat more easily from the sun, while light colours radiate heat to the surroundings more slowly. This may explain why chameleons are white at night – it would help them conserve heat.
But most of all, chameleons use colour for purposes of display. A chameleon's colour tells other chameleons much about its state of health and its attitude. Sick chameleons are literally off-colour, usually having pale hues that don't match their surroundings. As I've said before, threatened and angry chameleons (well, at least the Flap-necked and a few other species) turn blackish. The most vivid hues and most spectacular colour changes can be seen when males compete for females. They even seem to be able to intimidate each other with their colours! The Flap-Necked chameleon is not the most brightly coloured, but has vivid orange skin in its throat grooves that feature strongly in these displays. Other species have the ability to display bright red, blue and purple hues.
Then there are a few chameleon species that cannot change colour at all. The tiny leaf and ground chameleons are dull brown and stay that way – apart from becoming a bit darker or lighter.
In reproduction, chameleons are mostly like other lizards in laying eggs. They bury these in the soil. Clutch sizes vary from two to more than hundred eggs. In the Flap-necked Chameleon, a clutch of a few dozen eggs is laid in a hole the female excavates in the soil using her hands, feet and head. The babies are tiny, just about an inch long, and perfectly developed little things, and hunt on their own as soon as they hatch. Initially they can't change colour as well as when they are grown up – this they need to seem to learn, as well.
Some chameleons are ovo-viviparous: the eggs remain in the body and hatch there, after which the little babies are 'born'. This happens especially with the dwarf chameleons of South Africa, as well as with species inhabiting high, cool mountains in the more tropical countries of Africa.
Chameleon diversity is staggering! Within the constraints of their unique builds they nevertheless display astonishing variety between species. In size, they range from tiny leaf chameleons just a centimeter or two – half an inch to an inch – in length, to the huge Parson's Chameleon, Calumma parsoni, Oustalet's Chameleon, Furcifer oustaleti, and Meller's Chameleon, Chamaeleo (Trioceros) melleri, all of whom can exceed 60 cm, or 2 ft, in length. Species also differ in their colour-changing abilities and patterns, as I've said. Then they also differ in having different kinds of 'textures' of the granular 'scales' that cover their bodies, and in having different kinds of crests and ridges along their backs, heads, and throats, and also in many species, horns or growths on the heads, faces and noses. They differ in the kinds of displays used by the males – including different postures and different colour-changing sequences. Even the tiny, brown leaf-chameleons have a variety of textures and shapes to disguise them as different kinds of leaves.
There are about 160 species of chameleon recognized today. They occur in Africa, Madagascar, and some parts of Asia, with one species reaching southern Europe. The greatest diversity is on Madagascar, but there's also a wealth of species in the mountains of Africa. In the past, most chameleons were put in a single genus, Chamaeleo, with the dwarf chameleons (mostly of Southern and Eastern Africa) being distinguished as Bradypodion, and the African leaf chameleons being called Rampholeon, and those of Madagascar put in the genus Brookesia. Today, sometimes, a number of other genera are recognized. As we study them more we will certainly learn more about their diversity and relationships, likely leading to more genera and rearranged classifications. The highly adapted Desert Chameleon, despite living in a habitat shared by no other species, is nevertheless closely related to other more conventional chameleons, and is put in the genus Chamaeleo. By the way – 'Chamaeleo' means 'Earth Lion' – indicating the predatory ferocity of these little animals.
Evolution-wise, the first chameleons we know date back to 26 million years ago, but they were already highly specialized then. For certain their evolution goes back much further. Their closest lizard relatives are Agamas – African, Asian and Australian lizards with somewhat similar head shapes and eyelids – and Iguanas, similar lizards from the New World. The lizards called 'chameleons' in the Americas are actually Anoles, members of the Iguana family. But there are some 'real' chameleons in the New World – some have been introduced by humans to Hawaii, California, and Florida! But they're not native there; they were all brought from Africa and Madagascar. Chameleons have been evolving separately from the Agamas and Iguanas for probably 100 million years or so, and today are clearly a 'real' group – all more closely related to each other than to any other kind of lizard.
In all parts of their range, they are preyed upon by mammals, birds and other reptiles like tree snakes. But they are most vulnerable to humans. Even though in many places like Madagascar, they are protected from deliberate harm by local taboos, they are under great pressure because of human-caused deforestation – most of the species inhabit forests. If global warming happens, it might also severely affect species with small distribution ranges – of which the dwarf chameleons of South Africa are a relevant example. Most of the species only occur in very restricted areas such as small patches of forest or scrub. Climate change could easily alter these patches of habitat beyond the abilities of the chameleons to adapt. On the other hand, the Flap-necked Chameleon is extremely widespread and inhabits a number of different kinds of habitat, and so is much less vulnerable. But overall, a lot of chameleon diversity is contained in such small areas – we really at this point should understand the importance of conserving remaining tropical and montane forest patches. Apart from chameleons, these still contain an enormous diversity of other unique, wonderful things as well.
