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Chameleons or chamaeleons family Chamaeleonidae are a distinctive and highly specialized clade of Old World lizards with Chameleon described as of June Chameleons are distinguished by their zygodactylous feet; their very extensive, not highly modified, rapidly Chameleon tongues; their swaying gait; [2] and crests or horns on their brow and snout. Most species, the larger Chameleon in particular, also have a Chameleon tail. Chameleons' eyes are independently mobile, but Chameleon aiming at a prey item, they focus forward in coordination, affording the animal stereoscopic Chameleon. Chameleons Chameleon adapted for climbing and visual hunting. They live in warm habitats that range from rain forest to desert conditions, with various species occurring Chameleon Africa, Madagascarsouthern Europe, and across southern Asia as far as Sri Lanka. They also have been introduced to HawaiiCaliforniaand FloridaChameleon often are kept as household pets. Since that time, however, the validity of this subfamily designation has been Chameleon subject of much debate, [10] although most phylogenetic studies support the notion Chameleon the pygmy chameleons Chameleon the Chameleon Brookesiinae are not a monophyletic group. While some authorities have previously preferred to use this subfamilial classification on the basis of the absence of evidence principle, [10] these authorities later abandoned this Chameleon division, no longer recognizing any subfamilies Chameleon the family Chamaeleonidae. Inhowever, Glaw reworked the subfamilial division by placing only the genera Brookesia and Palleon within the Brookesiinae subfamily, with all other genera being Chameleon in Chamaeleoninae. Some Chameleon species are able to change their skin colouration. Different chameleon species Chameleon able to vary their colouration and pattern through combinations of pink, blue, red, orange, green, black, Chameleon, light blue, yellow, turquoise, and purple. Chameleons change colour by changing the space between the guanine crystals, which changes the wavelength of light reflected off the Chameleon which changes the colour of the skin. Colour change in chameleons has functions in camouflagebut most commonly in social Chameleon and in reactions to temperature and other conditions. The relative importance of these functions varies with the circumstances, as well as the species. Colour change signals a chameleon's Chameleon condition and intentions to other chameleons. Some species, such as Smith's dwarf chameleonadjust their colours for camouflage in accordance Chameleon the vision Chameleon the specific predator species bird or snake Chameleon which they are being threatened. The desert-dwelling Namaqua chameleon also uses colour change Chameleon an aid to thermoregulationbecoming black in the cooler Chameleon to absorb heat more efficiently, then a lighter grey colour Chameleon reflect light during the heat of the day. It may show both colors at the same time, neatly separated left from right by the spine. For Chameleon long time it was thought that chameleons change colour by dispersion of pigment-containing organelles within their skin. However, research conducted in Chameleon panther chameleons has shown that pigment movement only represents part of the mechanism. Chameleons have Chameleon superimposed layers within their skin Chameleon control their colour and thermoregulation. The top layer contains a lattice of guanine nanocrystals, and by exciting this lattice the Chameleon between the nanocrystals can be manipulated, which in turn affects which wavelengths of light are reflected and which are absorbed. Exciting the lattice increases the distance between the nanocrystals, and Chameleon skin reflects longer wavelengths of light. Thus, in a relaxed state the crystals reflect blue and green, but in an excited state Chameleon longer wavelengths such as yellow, orange, green, and red Chameleon reflected. The skin of a chameleon also contains some yellow pigments, which combined with the blue reflected by a Chameleon crystal lattice results in the characteristic green color which is common of many chameleons in their relaxed state. Chameleon color palettes have evolved through evolution and environment. Chameleons living in the forest have a more Chameleon and colorful palette compared to those living in the desert or savanna, which have more of a basic, brown and charred palette. The oldest described chameleon is Anqingosaurus brevicephalus from the Middle Paleocene about Other chameleon fossils include Chamaeleo caroliquarti from the Lower Miocene about 13—23 mya of the Czech Republic and Germany, and Chamaeleo intermedius from the Upper Miocene about 5—13 mya of Kenya. The chameleons are probably far older than Chameleon, perhaps sharing a common ancestor with iguanids and agamids more than mya agamids being Chameleon closely related. Since fossils have been found in Africa, Europe and Asia, chameleons were certainly once Chameleon widespread than they are today. Although nearly half of all chameleon species today live in Madagascar, this offers no basis for speculation that chameleons Chameleon originate from there. The diverse speciation of chameleons has been theorized to have directly reflected the increase in open habitats savannah, grassland, and heathland that accompanied the Oligocene period. Monophyly of the family is supported by several studies. Daza et al. The authors noted Chameleon the lizard has "short and wide skull, large orbits, elongated and robust lingual process, frontal with parallel margins, incipient Chameleon boss, reduced vomers, absent retroarticular process, low presacral vertebral count between 15 and 17 and extremely short, curled tail"; the authors considered these traits to be indicative of the lizard's affiliation with Chameleon. The phylogenetic analysis conducted by the authors Chameleon that the lizard was Chameleon stem -chamaeleonid. While the exact evolutionary history of color change in chameleons is still unknown, there is one aspect of the evolutionary history of chameleon color change that has already been conclusively studied: the effects of signal efficacy. Signal efficacy, or how well the signal can be seen against its background, has been shown to correlate directly to spectral qualities of chameleon displays. It was demonstrated that chameleons in brighter areas tended to present brighter signals, Chameleon chameleons in darker areas tended to present relatively more contrasting signals to their backgrounds. This finding suggests that signal Chameleon and thus habitat has affected the evolution of chameleon signaling. Stuart-Fox et al. Many species are sexually dimorphicand males are typically much more ornamented than the female chameleons. The feet of chameleons are highly adapted to arboreal Chameleonand Chameleon such as Chamaeleo namaquensis that have secondarily adopted a terrestrial habit have retained the same foot morphology with little modification. On each foot, the Chameleon clearly distinguished toes are grouped into two fascicles. The toes in each fascicle are bound into a Chameleon group of either two or three, giving each foot a tongs -like appearance. On the front feet, the outer, lateralgroup contains two toes, whereas the inner, medialgroup contains three. On the rear Chameleon, this arrangement is reversed, the medial group containing two toes, and the Chameleon group three. These specialized feet allow chameleons to grip tightly onto Chameleon or rough branches. Furthermore, each toe Chameleon equipped with a sharp claw to afford a grip on surfaces such as bark when climbing. It is common to refer to the feet of chameleons as didactyl or zygodactylthough neither term is fully satisfactory, both being used in describing totally different feet, such as the zygodactyl feet of parrots or didactyl feet of sloths or ostriches, none of which Chameleon significantly like chameleon feet. Although "zygodactyl" is reasonably descriptive of chameleon foot anatomy, Chameleon foot structure does not Chameleon that of parrots, to which the term was first applied. As for didactyly, chameleons visibly have five toes on each foot, not two. Chameleon chameleons have a crest of small spikes extending along the spine from the proximal part of the tail to the neck; both the extent and size of the spikes varies between species and individuals. These spikes help break up the definitive outline of the chameleon, which aids it when trying to blend into a background. Chameleons have the most distinctive eyes of any reptile. The upper and lower eyelids are joined, with only a pinhole large enough for Chameleon pupil to see through. Each eye can pivot and focus independently, allowing the chameleon to observe two different objects simultaneously. This gives them a full degree arc of vision around their bodies. Prey is located using monocular depth perceptionChameleon stereopsis. Like snakeschameleons do not have an Chameleon or a middle earso there is neither an ear opening nor an eardrum. Chameleons can see in both visible Chameleon ultraviolet light. All chameleons are primarily insectivores that feed by ballistically projecting their long tongues from their mouths to capture prey located some distance away. The chameleon's tongue apparatus consists of highly modified hyoid bonestongue musclesand collagenous Chameleon. Tongue projection occurs at extremely high performance, reaching the prey in as little as 0. One consequence of the incorporation of an elastic recoil mechanism to the tongue projection mechanism is relative Chameleon insensitivity Chameleon tongue projection relative to tongue retraction, which is powered by muscle contraction alone, and is heavily thermally sensitive. Certain species Chameleon chameleons have bones that glow when under ultraviolet lightalso known Chameleon biogenic fluorescence. Chameleons primarily live in the mainland of sub-Saharan Africa and on the island of Madagascar, although a few Chameleon live in Chameleon Africa Chameleon, southern Europe Spain, Italy, Greecethe Middle Eastsouthern IndiaSri Lankaand several smaller islands in the western Indian Ocean. There are introduced, feral populations of veiled and Jackson's chameleons in Hawaii Chameleon, and isolated pockets of feral Jackson's chameleons have been reported in CaliforniaFlorida and Texas. Chameleons inhabit all kinds of tropical and mountain rain forestssavannas Chameleon, and sometimes deserts and steppes. The typical chameleons from the subfamily Chamaeleoninae are arborealusually living in trees or bushes, although a few notably the Namaqua chameleon are partially or largely terrestrial. Most species from the subfamily Chameleon, which includes the genera Brookesia Chameleon, Rieppeleonand Rhampholeonlive low in vegetation or on the ground among leaf litter. Many species of chameleons are threatened by extinction. Declining chameleon numbers are Chameleon to habitat loss. Chameleons are mostly oviparouswith some being ovoviviparous. The oviparous species lay eggs three to six weeks after copulation. Clutch sizes vary greatly with species. Small Brookesia species may only lay two to four eggs, while large veiled chameleons Chamaeleo calyptratus have been known to lay clutches of 20— veiled chameleons and 10—40 Chameleon chameleons eggs. Clutch sizes can Chameleon vary greatly among the same species. Eggs generally hatch after four to 12 months, again depending on Chameleon. The eggs of Parson's chameleon Calumma parsoniia Chameleon which is rare Chameleon captivity, are believed to take more than 24 months to hatch. Chameleon lay flexible-shelled eggs which are affected by environmental Chameleon during incubation. The egg mass Chameleon the most important in differentiating survivors of Chameleon during incubation. An increase in egg mass will depend on temperature and water potential. The ovoviviparous Chameleon, such as the Jackson's chameleon Trioceros jacksonii have a five- to seven-month gestation period. Each young chameleon is Chameleon within the sticky transparent membrane of its yolk sac. The Chameleon presses each egg onto a branch, where it sticks. The membrane bursts and the newly hatched chameleon frees itself and climbs away to hunt for itself and hide from predators. The female can have up to 30 live young from one gestation. Chameleons generally eat insectsbut larger species, such as the common chameleon, may also take other Chameleon and young birds. Chameleons are preyed upon and consumed by a variety of other Chameleon. Birds and snakes represent the most important predators of adult chameleons and invertebrates, especially ants, Chameleon a high predatory pressure on chameleon eggs and juveniles. Chameleon if detected, chameleons actively defend themselves. They adopt a defensive body posture, present an attacker a laterally flattened body to appear larger, warn with an open mouth and, if needed, utilize feet and jaws to fight back. Chameleons are parasitized by nematode worms, including threadworms Filarioidea. Threadworms can be transmitted by biting insects such as ticks and mosquitoes. Other roundworms are transmitted through food Chameleon with roundworm eggs; the larvae burrow through the wall of the intestine into the Chameleon. Chameleons are subject to several protozoan parasites, such as Plasmodium which causes malariaTrypanosoma which causes sleeping sicknessand Leishmania which causes leishmaniasis. Chameleon | Definition of Chameleon by Merriam-Webster

All rights reserved. Chameleons mostly live in the rain forests and deserts of Africa. The color of their skin helps them blend in with their habitats. Chameleons that hang out in trees are usually green. Those that live in deserts are most often brown. They often change color to warm Chameleon or cool down. Turning darker helps warm the animals because the dark colors absorb more Chameleon. They also switch shades Chameleon communicate with other chameleons, using bright colors to attract potential mates or warn enemies. So how exactly do chameleons change Chameleon The outer layer of their skin is see-through. Beneath that are layers of special cells filled with pigment— the substance that gives plants and animals including you color. To display a new color, the brain Chameleon a message for these cells to get bigger Chameleon smaller. As this happens, pigments Chameleon different cells are released, and they mix with each other to create new skin tones. For instance, red and blue pigment may mix to make the chameleon look purple. Over species Chameleon chameleons exist, ranging from the Chameleon of your thumbnail to that of a house cat. Some species of chameleon such as the Chameleon chameleon are endangered, but others like the Drakensberg dwarf chameleon are not. No matter their differences, all chameleons have a prize pair of eyes. Their peepers can move in two different directions Chameleon once, Chameleon the lizards a panoramic view of their surroundings. This eye-popping reptile really knows how to scale up the cool Chameleon. Watch this episode of Moment of… to find out! Continue Reading. Chameleon Facts | Live Science

Chameleonfamily Chamaeleonidaeany of a group of Chameleon arboreal tree-dwelling Old World lizards best known for their ability to change body colour. Other characteristics of chameleons include zygodactylous feet with Chameleon fused into opposed bundles of two and threeacrodont dentition with the teeth attached to the edge of the jaweyes that move independently, atrophied venom glands that produce harmless trace amounts of venom, and a long, slender projectile Chameleon. The Chameleon has also been Chameleon to the false chameleon, or anolea New World lizard of the genus Anolis family Iguanidae. Four genera of true chameleons have been described: Bradypodion Chameleon, BrookesiaChamaeleo Chameleon, and Rhampholeon. Chameleon additional genera Calumma and Furcifer are recognized by some researchers. More than species are currently known, and Chameleon ones remain to be named. About half of Chameleon species occur only in MadagascarChameleon others occur mostly in sub-Saharan Africa. Two species occur in Chameleon one is native to southern India and Sri Lanka Chamaeleo zeylanicusand the other the European chameleon, C. The most familiar chameleons belong to Chameleon genus Chamaeleoand these have prehensile tails that wrap in a coil-like fashion around limbs to maintain balance. In contrast, most species of pigmy chameleons in the genera Brookesia Madagascar and Rhampholeon Africa have short stubby tails that are not prehensile; however, pigmy chameleons in Bradypodion have longer tails Chameleon are Chameleon. Most chameleons, however, are 17—25 cm 7—10 inches long. The body is laterally compressed, the Chameleon is sometimes curled, and the bulged eyes move independently of one another. Also, some chameleons possess helmet-shaped heads. Some species have conspicuous head ornamentation that may Chameleon as many as three long horns projecting forward. Such features are either exclusive to or better developed in males, and at least some of these features are related to territorial defense. A defending male responds to an invader by expanding the body, puffing out the Chameleon, and elevating or waving special head flaps. If this display fails Chameleon intimidate the Chameleon, the defender charges and snaps his jaws. The differences in appearance between the sexes result from a process known as Chameleon selectionin which individual males with extreme ornamentation have a Chameleon breeding success; they pass on the genes that form the basis for these features at a faster rate than those individuals lacking ornamentation. Each species Chameleon capable Chameleon undergoing a particular range of colour change. The mechanism involves the dispersal or concentration of pigment granules Chameleon cells in the cells that contain them. These cells are under the control Chameleon the autonomic Chameleon system. Colour change is determined by such environmental factors as light and temperature as well as by emotions—such as Chameleon and those associated with victory or defeat in battle with another chameleon. Many chameleons can assume a green, yellow, cream, or dark brown coloration. Frequently, this occurs with lighter or darker spots on the background colour of the body. Some of the most striking colours appear in males during mating. Some achieve colour patterns that are so vivid and complex that it is hard to imagine that they serve any natural purpose. It is a popular misconception that the chameleon changes its colour to match that of the background. Although many other lizards also use the tongue to capture prey, most Chameleon expel it only a short distance. In contrast, chameleons can launch their tongues at great speed to a Chameleon of more than twice their body length, and they can strike and capture their prey with great accuracy. Most species are egg layers. Typically, females descend from their shrub or tree to bury between 2 and 40 eggs in the soil or rotting logs, and incubation lasts about three months. In addition, the Madagascan chameleon, F. The eggs of F. After an intense competition for mates, eggs are laid in February, and the entire adult population perishes. Chameleon Article Media Additional Info. Print Cite. Facebook Twitter. Give Feedback External Websites. Let us know if you have suggestions Chameleon improve this article requires login. External Websites. Articles from Britannica Encyclopedias Chameleon elementary and high school students. Coauthor of Herpetology and others. See Chameleon History. Get exclusive access Chameleon content from our First Edition with your Chameleon. Subscribe today. Learn More in these related Britannica articles:. Still, true chameleons rely mainly on the tonglike arrangement of…. The chameleons, of those species studied thus far, have only a few sensory hair cells 40 Chameleon 50 in the auditory papilla. The geckos,…. Unlike other arboreal Chameleon, chameleons possess a Chameleon grasping tail and Chameleon feet—i. Although these adaptations are inferior for vertical climbing, they are superior for locomotion on vertical or inclined, slender branches. Arboreal snakes tend to have either prehensile tails or…. History at your fingertips. Sign up Chameleon to see what happened On This Dayevery day in your inbox! Email address. By signing up, you agree to our Privacy Notice. Be on the lookout Chameleon your Britannica newsletter to get trusted stories delivered right to your inbox.