In most biological nomenclature, a scale is a small rigid plate that grows out of an animal's skin to provide protection. In lepidopteran species, scales are plates on the surface of the insect wing, provide coloration. Scales are quite common and have evolved multiple times through convergent evolution, with varying structure and function. Scales are classified as part of an organism's integumentary system. There are various types of scales according to class of animal. Fish scales are dermally derived in the mesoderm; this fact distinguishes them from reptile scales paleontologically. Genetically, the same genes involved in tooth and hair development in mammals are involved in scale development. True cosmoid scales can only be found on the Sarcopterygians; the inner layer of the scale is made of lamellar bone. On top of this lies a layer of spongy or vascular bone and a layer of dentine-like material called cosmine; the upper surface is keratin. The coelacanth has modified cosmoid scales that lack cosmine and are thinner than true cosmoid scales.
Ganoid scales can be found on gars and reedfishes. Ganoid scales are similar to cosmoid scales, but a layer of ganoin lies over the cosmine layer and under the enamel. Ganoin scales are diamond shaped and hard. Within the ganoin are guanine compounds, iridescent derivatives of guanine found in a DNA molecule; the iridescent property of these chemicals provide the ganoin its shine. Placoid scales are found on cartilaginous fish including sharks; these scales called denticles, are similar in structure to teeth, have one median spine and two lateral spines. Leptoid scales are found on higher-order bony fish; as they grow they add concentric layers. They are arranged so as to overlap in a head-to-tail direction, like roof tiles, allowing a smoother flow of water over the body and therefore reducing drag, they come in two forms: Cycloid scales have a smooth outer edge, are most common on fish with soft fin rays, such as salmon and carp. Ctenoid scales have a toothed outer edge, are found on fish with spiny fin rays, such as bass and crappie.
Reptile scale types include: cycloid and keeled. Scales vary in size, the stouter, larger scales cover parts that are exposed to physical stress, while scales are small around the joints for flexibility. Most snakes have extra broad scales on each scale covering the belly from side to side; the scales of all reptiles have an epidermal component, but many reptiles, such as crocodilians and turtles, have osteoderms underlying the epidermal scale. Such scales are more properly termed scutes. Snakes and many lizards lack osteoderms. All reptilian scales have a dermal papilla underlying the epidermal part, it is there that the osteoderms, if present, would be formed. Birds' scales are found on the toes and metatarsus, but may be found further up on the ankle in some birds; the scales and scutes of birds were thought to be homologous to those of reptiles, but are now agreed to have evolved independently, being degenerate feathers. An example of a scaled mammal is the pangolin, its scales are are used for protection, similar to an armadillo's armor.
They have been convergently evolved, being unrelated to the animal's distant reptile ancestors, except that they use a similar gene. On the other hand, the musky rat-kangaroo, has scales on its feet and tail; the precise nature of its purported scales has not been studied in detail, but they appear to be structurally different from pangolin scales. Anomalures have scales on their tail undersides. Foot pad epidermal tissues in most mammal species have been compared to the scales of other vertebrates, they are derived from cornification processes or stunted fur much like avian reticulae are derived from stunted feathers. Butterflies and moths - the order Lepidoptera - have membranous wings covered in delicate, powdery scales, which are modified setae; each scale consists of a series of tiny stacked platelets of organic material, butterflies tend to have the scales broad and flattened, while moths tend to have the scales narrower and more hair like. Scales are pigmented, but some types of scales are metallic, or iridescent, without pigments.
The most common color produced in this fashion is blue, such as in the Morpho butterflies. Other colors can be seen on the sunset moth. Scale Armour
Squamata is the largest order of reptiles, comprising lizards and amphisbaenians, which are collectively known as squamates or scaled reptiles. With over 10,000 species, it is the second-largest order of extant vertebrates, after the perciform fish, equal in number to the Saurischia. Members of the order are distinguished by their skins, which bear horny shields, they possess movable quadrate bones, making it possible to move the upper jaw relative to the neurocranium. This is visible in snakes, which are able to open their mouths wide to accommodate comparatively large prey. Squamata is the most variably sized order of reptiles, ranging from the 16 mm dwarf gecko to the 5.21 m green anaconda and the now-extinct mosasaurs, which reached lengths of over 14 m. Among other reptiles, squamates are most related to the tuatara, which superficially resembles lizards. Squamates are a monophyletic sister group to the rhynchocephalians, members of the order Rhynchocephalia; the only surviving member of Rhynchocephalia is the tuatara.
Squamata and Rhynchocephalia form the subclass Lepidosauria, the sister group to Archosauria, the clade that contains crocodiles and birds, their extinct relatives. Fossils of rhynchocephalians first appear in the Early Triassic, meaning that the lineage leading to squamates must have existed at the time. Scientists believe crown group squamates originated in the Early Jurassic based on the fossil record; the first fossils of geckos and snakes appear in the Middle Jurassic. Other groups like iguanians and varanoids appeared in the Cretaceous. Polyglyphanodontians, a distinct clade of lizards, mosasaurs, a group of predatory marine lizards that grew to enormous sizes appeared in the Cretaceous. Squamates suffered a mass extinction at the Cretaceous–Paleogene boundary, which wiped out polyglyphanodontians and many other distinct lineages; the relationships of squamates is debatable. Although many of the groups recognized on the basis of morphology are still accepted, our understanding of their relationships to each other has changed radically as a result of studying their genomes.
Iguanians were long thought to be the earliest crown group squamates based on morphological data, genetic data suggests that geckoes are the earliest crown group squamates. Iguanians are now united with anguimorphs in a clade called Toxicofera. Genetic data suggests that the various limbless groups. A study in 2018 found that Megachirella, an extinct genus of lepidosaur that lived about 240 million years ago during the Middle Triassic, was a stem-squamate, making it the oldest known squamate; the phylogenetic analysis was conducted by performing high-resolution microfocus X-ray computed tomography scans on the fossil specimen of Megachirella to gather detailed data about its anatomy. This data was compared with a phylogenetic dataset combining the morphological and molecular data of 129 extant and extinct reptilian taxa; the comparison revealed. The study found that geckos are the earliest crown group squamates not iguanians; the male members of the group Squamata have hemipenes, which are held inverted within their bodies, are everted for reproduction via erectile tissue like that in the human penis.
Only one is used at a time, some evidence indicates that males alternate use between copulations. The hemipenis has a variety of shapes, depending on the species, it bears spines or hooks, to anchor the male within the female. Some species have forked hemipenes. Due to being everted and inverted, hemipenes do not have a enclosed channel for the conduction of sperm, but rather a seminal groove that seals as the erectile tissue expands; this is the only reptile group in which both viviparous and ovoviviparous species are found, as well as the usual oviparous reptiles. Some species, such as the Komodo dragon, can reproduce asexually through parthenogenesis. There have been studies on how sexual selection manifests itself in lizards. Snakes use a variety of tactics in acquiring mates. Ritual combat between males for the females they want to mate with includes topping, a behavior exhibited by most viperids, in which one male will twist around the vertically elevated fore body of its opponent and forcing it downward.
It is common for neck biting to occur. Parthenogenesis is a natural form of reproduction in which the growth and development of embryos occur without fertilization. Agkistrodon contortrix and Agkistrodon piscivorus can reproduce by facultative parthenogenesis; that is, they are capable of switching from a sexual mode of reproduction to an asexual mode. The type of parthenogenesis that occurs is automixis with terminal fusion, a process in which two terminal products from the same meiosis fuse to form a diploid zygote; this process leads to genome wide homozygosity, expression of deleterious recessive alleles and to developmental abnormalities. Both captive-born and wild-born A. contortrix and A. piscivorus appear to be capable of this form of parthenogenesis. Reproduction in squamate reptiles is ordinarily sexual, with males having a ZZ pair of sex determining chromosomes, females a ZW pair. However, the Colombian Rainbow boa, Epicrates maurus, can reproduce by facultative parthenogenesis resulting in production of WW female pr
Texas horned lizard
The Texas horned lizard is one of about 14 North American species of spikey-bodied reptiles called horned lizards. P. cornutum ranges from Colorado and Kansas to northern Mexico, from southeastern Arizona to Texas. Isolated, introduced populations are found in the Carolinas and northern Florida. Texas horned lizards may be native to Louisiana and Arkansas; the horned lizard is popularly called a "horned toad", or "horned frog", but it is neither a toad nor a frog. The popular names come from the lizard's rounded body and blunt snout, which give it a decidedly batrachian appearance. Phrynosoma means "toad-bodied" and cornutum means "horned"; the lizard's horns contain true bone. The Texas horned lizard is the largest-bodied and most distributed of the 14 species of horned lizards in the western United States and Mexico; the average Texas horned lizard is 69 mm in snout-vent length, but the upper boundary for males is 94 mm and for females it is 114 mm. Although its coloration serves as camouflage against predation, when threatened by a predator, a horned lizard puffs up and appears fat, which causes its body scales to protrude, making it difficult to swallow.
The Texas horned lizard, along with at least three other species of the genus Phrynosoma has the ability to squirt an aimed stream of blood from the corners of the eyes and sometimes from its mouth for a distance up to 5 ft. They do this by restricting the blood flow leaving the head, thereby increasing blood pressure and rupturing tiny vessels around the eyelids; this not only confuses would-be predators, but the blood is mixed with a chemical, foul-tasting to canine predators such as wolves and domestic dogs. This novel behavior is observed to be effective in defense. About 70% of the Texas horned lizard's diet is made up of harvester ants, though they supplement these with termites and grasshoppers. In recent years, the species has declined by about 30% of its range, though it may be making a comeback; the decline is blamed on overuse of pesticides and the spread of nonnative aggressive and fiercely territorial red imported fire ants. Both eradicate harvester ant colonies; the Texas horned lizard is now a protected species, and, in Texas, it is illegal to take, transport or sell them without a special permit.
A University of Texas publication notes that horned lizard populations continue to disappear throughout the southwest despite protective legislation. The Texas horned lizard has disappeared from half of its geographic range. Population declines are attributed to loss of habitat, human eradication of the ant populations upon which the lizards prey, displacement of native ant populations by invading fire ants, predation by domestic dogs and cats. In 2014, the Center for Biological Diversity in Tucson, Arizona petitioned the Oklahoma Department of Wildlife Conservation to have the Texas horned lizard put on the endangered species list due to the massive declines of its population in Oklahoma, where it was once plentiful; the Center said it may seek protection for the animal on a Federal level. In Texas, the creature has been declared threatened and a breeding and reintroduction program has been started by the Fort Worth Zoo. Hatchlings are bred and released in targeted areas in the hope that with a large number of animals, enough will survive to grow the population in the wild.
In such reptile reintroduction programs, less than one percent of a female's offspring will survive in the wild to adulthood. Horned lizards are studied by researchers at Texas Christian University, the nearby Fort Worth Zoo, Dallas Zoo with raw data and fieldwork done by state employees. Since 2010, the Dallas Zoo has been conducting a mark-and-recapture study on Texas horned lizards on the Rolling Plains Quail Research Ranch, a 4,700-acre preserve located in Fisher County, Texas. Dallas Zoo researchers capture animals, tag them, collect data, release them; the project’s goals are aimed at shedding light on the life history, population density, determining ecological conditions best suited for this threatened species. Further research toward their preservation is funded by sale of horned lizard "Keep Texas Wild" license plates. In addition, the Dallas Zoo and Houston Zoo are working to establish a captive colony of animals with several key reproductive successes taking place in 2015. Despite its fierce appearance, Texas horned lizards are docile creatures.
The Texas horned lizard is a sunbather, requires bright sunlight to produce vitamin D. Deprived of sunlight, the animal is unable to produce vitamin D and can suffer from vitamin deficiency. So, horned lizards are most found along the side of roads or other open, rocky areas, where they can lounge and take in sunlight. At night, the lizard buries itself in sand. Otherwise, horned lizards are most found near harvester ant hills. Although they prefer to move little, horned lizards can move quite fast if they feel a predator is in the area, dart into thick grass and foliage to escape. Horned lizards are excellent diggers, can burrow underground to escape threats. Research aimed at preservation has revealed the Texas horned lizard is genetically diverse, isolated pockets of genetically distinct subspecies have been found throughout Texas
Idaho is a state in the northwestern region of the United States. It borders the state of Montana to the east and northeast, Wyoming to the east and Utah to the south, Washington and Oregon to the west. To the north, it shares a small portion of the Canadian border with the province of British Columbia. With a population of 1.7 million and an area of 83,569 square miles, Idaho is the 14th largest, the 12th least populous and the 7th least densely populated of the 50 U. S. states. The state's capital and largest city is Boise. Idaho prior to European settlement was inhabited by Native American peoples, some of whom still live in the area. In the early 19th century, Idaho was considered part of the Oregon Country, an area disputed between the U. S. and the United Kingdom. It became U. S. territory with the signing of the Oregon Treaty of 1846, but a separate Idaho Territory was not organized until 1863, instead being included for periods in Oregon Territory and Washington Territory. Idaho was admitted to the Union on July 3, 1890, becoming the 43rd state.
Forming part of the Pacific Northwest, Idaho is divided into several distinct geographic and climatic regions. In the state's north, the isolated Idaho Panhandle is linked with Eastern Washington, with which it shares the Pacific Time Zone – the rest of the state uses the Mountain Time Zone; the state's south includes the Snake River Plain, while the south-east incorporates part of the Great Basin. Idaho is quite mountainous, contains several stretches of the Rocky Mountains; the United States Forest Service holds about 38 % of the most of any state. Industries significant for the state economy include manufacturing, mining and tourism. A number of science and technology firms are either headquartered in Idaho or have factories there, the state contains the Idaho National Laboratory, the country's largest Department of Energy facility. Idaho's agricultural sector supplies many products, but the state is best known for its potato crop, which comprises around one-third of the nationwide yield; the official state nickname is the "Gem State".
The name's origin remains a mystery. In the early 1860s, when the United States Congress was considering organizing a new territory in the Rocky Mountains, eccentric lobbyist George M. Willing suggested the name "Idaho", which he claimed was derived from a Shoshone language term meaning "the sun comes from the mountains" or "gem of the mountains". Willing claimed he had invented the name. Congress decided to name the area Colorado Territory when it was created in February 1861. Thinking they would get a jump on the name, locals named a community in Colorado "Idaho Springs". However, the name "Idaho" did not fall into obscurity; the same year Congress created Colorado Territory, a county called Idaho County was created in eastern Washington Territory. The county was named after a steamship named Idaho, launched on the Columbia River in 1860, it is unclear after Willing's claim was revealed. Regardless, part of Washington Territory, including Idaho County, was used to create Idaho Territory in 1863.
Despite this lack of evidence for the origin of the name, many textbooks well into the 20th century repeated as fact Willing's account the name "Idaho" derived from the Shoshone term "ee-da-how". A 1956 Idaho history textbook says:"Idaho" is a Shoshoni Indian exclamation; the word consists of three parts. The first is "Ee", which in English conveys the idea of "coming down"; the second is "dah", the Shoshoni stem or root for both "sun" and "mountain". The third syllable, "how", denotes the exclamation and stands for the same thing in Shoshoni that the exclamation mark does in the English language; the Shoshoni word is "Ee-dah-how", the Indian thought thus conveyed when translated into English means, "Behold! the sun coming down the mountain. An alternative etymology attributes the name to the Plains Apache word "ídaahę́", used in reference to The Comanche. Idaho borders six U. S. states and one Canadian province. The states of Washington and Oregon are to the west and Utah are to the south, Montana and Wyoming are to the east.
Idaho shares a short border with the Canadian province of British Columbia to the north. The landscape is rugged with some of the largest unspoiled natural areas in the United States. For example, at 2.3 million acres, the Frank Church-River of No Return Wilderness Area is the largest contiguous area of protected wilderness in the continental United States. Idaho is a Rocky Mountain state with scenic areas; the state has snow-capped mountain ranges, vast lakes and steep canyons. The waters of the Snake River rush through the deepest gorge in the United States. Shoshone Falls plunges down rugged cliffs from a height greater than Niagara Falls; the major rivers in Idaho are the Snake River, the Clark Fork/Pend Oreille River, the Clearwater River, the Salmon River. Other significant rivers include the Coeur d'Alene River, the Spokane River, the Boise River, the Payette River; the Salmon River empties into the Snake in Hells Canyon and forms the southern boundary of Nez Perce County on its north shore, of which Lewiston is the county seat.
The Port of Lewiston, at the confluence of the Clearwater and the Snake Rivers is the farthest inland seaport on the West Coast at 465 river miles from the Pacific at Astoria, Oregon. Idaho's highest point is 12,662 ft, in the Lost River Range north of Mackay. Idaho's lowest poi
North America is a continent within the Northern Hemisphere and all within the Western Hemisphere. It is bordered to the north by the Arctic Ocean, to the east by the Atlantic Ocean, to the west and south by the Pacific Ocean, to the southeast by South America and the Caribbean Sea. North America covers an area of about 24,709,000 square kilometers, about 16.5% of the earth's land area and about 4.8% of its total surface. North America is the third largest continent by area, following Asia and Africa, the fourth by population after Asia and Europe. In 2013, its population was estimated at nearly 579 million people in 23 independent states, or about 7.5% of the world's population, if nearby islands are included. North America was reached by its first human populations during the last glacial period, via crossing the Bering land bridge 40,000 to 17,000 years ago; the so-called Paleo-Indian period is taken to have lasted until about 10,000 years ago. The Classic stage spans the 6th to 13th centuries.
The Pre-Columbian era ended in 1492, the transatlantic migrations—the arrival of European settlers during the Age of Discovery and the Early Modern period. Present-day cultural and ethnic patterns reflect interactions between European colonists, indigenous peoples, African slaves and their descendants. Owing to the European colonization of the Americas, most North Americans speak English, Spanish or French, their culture reflects Western traditions; the Americas are accepted as having been named after the Italian explorer Amerigo Vespucci by the German cartographers Martin Waldseemüller and Matthias Ringmann. Vespucci, who explored South America between 1497 and 1502, was the first European to suggest that the Americas were not the East Indies, but a different landmass unknown by Europeans. In 1507, Waldseemüller produced a world map, in which he placed the word "America" on the continent of South America, in the middle of what is today Brazil, he explained the rationale for the name in the accompanying book Cosmographiae Introductio:... ab Americo inventore... quasi Americi terram sive Americam.
For Waldseemüller, no one should object to the naming of the land after its discoverer. He used the Latinized version of Vespucci's name, but in its feminine form "America", following the examples of "Europa", "Asia" and "Africa". Other mapmakers extended the name America to the northern continent, In 1538, Gerard Mercator used America on his map of the world for all the Western Hemisphere; some argue that because the convention is to use the surname for naming discoveries, the derivation from "Amerigo Vespucci" could be put in question. In 1874, Thomas Belt proposed a derivation from the Amerrique mountains of Central America. Marcou corresponded with Augustus Le Plongeon, who wrote: "The name AMERICA or AMERRIQUE in the Mayan language means, a country of perpetually strong wind, or the Land of the Wind, and... the can mean... a spirit that breathes, life itself." The United Nations formally recognizes "North America" as comprising three areas: Northern America, Central America, The Caribbean.
This has been formally defined by the UN Statistics Division. The term North America maintains various definitions in accordance with context. In Canadian English, North America refers to the land mass as a whole consisting of Mexico, the United States, Canada, although it is ambiguous which other countries are included, is defined by context. In the United States of America, usage of the term may refer only to Canada and the US, sometimes includes Greenland and Mexico, as well as offshore islands. In France, Portugal, Romania and the countries of Latin America, the cognates of North America designate a subcontinent of the Americas comprising Canada, the United States, Mexico, Greenland, Saint Pierre et Miquelon, Bermuda. North America has been referred to by other names. Spanish North America was referred to as Northern America, this was the first official name given to Mexico. Geographically the North American continent has many subregions; these include cultural and geographic regions. Economic regions included those formed by trade blocs, such as the North American Trade Agreement bloc and Central American Trade Agreement.
Linguistically and culturally, the continent could be divided into Latin America. Anglo-America includes most of Northern America and Caribbean islands with English-speaking populations; the southern North American continent is composed of two regions. These are the Caribbean; the north of the continent maintains recognized regions as well. In contrast to the common definition of "North America", which encompasses the whole continent, the term "North America" is sometimes used to refer only to Mexico, the United States, Greenland; the term Northern America refers to the northern-most countries and territories of North America: the United States, Bermuda, St. Pierre and Miquelon and Greenland. Although the term does not refer to a unifie
Binomial nomenclature called binominal nomenclature or binary nomenclature, is a formal system of naming species of living things by giving each a name composed of two parts, both of which use Latin grammatical forms, although they can be based on words from other languages. Such a name is called a binomen, binominal name or a scientific name; the first part of the name – the generic name – identifies the genus to which the species belongs, while the second part – the specific name or specific epithet – identifies the species within the genus. For example, humans belong within this genus to the species Homo sapiens. Tyrannosaurus rex is the most known binomial; the formal introduction of this system of naming species is credited to Carl Linnaeus beginning with his work Species Plantarum in 1753. But Gaspard Bauhin, in as early as 1623, had introduced in his book Pinax theatri botanici many names of genera that were adopted by Linnaeus; the application of binomial nomenclature is now governed by various internationally agreed codes of rules, of which the two most important are the International Code of Zoological Nomenclature for animals and the International Code of Nomenclature for algae and plants.
Although the general principles underlying binomial nomenclature are common to these two codes, there are some differences, both in the terminology they use and in their precise rules. In modern usage, the first letter of the first part of the name, the genus, is always capitalized in writing, while that of the second part is not when derived from a proper noun such as the name of a person or place. Both parts are italicized when a binomial name occurs in normal text, thus the binomial name of the annual phlox is now written as Phlox drummondii. In scientific works, the authority for a binomial name is given, at least when it is first mentioned, the date of publication may be specified. In zoology "Patella vulgata Linnaeus, 1758"; the name "Linnaeus" tells the reader who it was that first published a description and name for this species of limpet. "Passer domesticus". The original name given by Linnaeus was Fringilla domestica; the ICZN does not require that the name of the person who changed the genus be given, nor the date on which the change was made, although nomenclatorial catalogs include such information.
In botany "Amaranthus retroflexus L." – "L." is the standard abbreviation used in botany for "Linnaeus". "Hyacinthoides italica Rothm. – Linnaeus first named this bluebell species Scilla italica. The name is composed of two word-forming elements: "bi", a Latin prefix for two, "-nomial", relating to a term or terms; the word "binomium" was used in Medieval Latin to mean a two-term expression in mathematics. Prior to the adoption of the modern binomial system of naming species, a scientific name consisted of a generic name combined with a specific name, from one to several words long. Together they formed a system of polynomial nomenclature; these names had two separate functions. First, to designate or label the species, second, to be a diagnosis or description. In a simple genus, containing only two species, it was easy to tell them apart with a one-word genus and a one-word specific name; such "polynomial names" may sometimes look like binomials, but are different. For example, Gerard's herbal describes various kinds of spiderwort: "The first is called Phalangium ramosum, Branched Spiderwort.
The other... is aptly termed Phalangium Ephemerum Virginianum, Soon-Fading Spiderwort of Virginia". The Latin phrases are short descriptions, rather than identifying labels; the Bauhins, in particular Caspar Bauhin, took some important steps towards the binomial system, by pruning the Latin descriptions, in many cases to two words. The adoption by biologists of a system of binomial nomenclature is due to Swedish botanist and physician Carl von Linné, more known by his Latinized name Carl Linnaeus, it was in his 1753 Species Plantarum that he first began using a one-word "trivial name" together with a generic name in a system of binomial nomenclature. This trivial name is what is now known as specific name; the Bauhins' genus names were retained in many of these, but the descriptive part was reduced to a single word. Linnaeus's trivial names introduced an important new idea, namely that the function of a name could be to give a species a unique label; this meant. Thus Gerard's Phalangium ephemerum virginianum became Tradescantia virgi
Chuckwallas are large lizards found in arid regions of the southwestern United States and northern Mexico. Some are found on coastal islands; the six species of chuckwallas are all placed within the genus Sauromalus. The generic name, Sauromalus, is a combination of two Ancient Greek words:σαῦρος meaning "lizard" and ομαλυς meaning "flat"; the common name "chuckwalla" derives from the Shoshone word tcaxxwal or Cahuilla čaxwal, transcribed by Spaniards as chacahuala. Chuckwallas are wide-bodied lizards with flattened midsections and prominent bellies, their tails are thick. Loose folds of skin characterize the neck and sides of their bodies, which are covered in small, coarsely granular scales; the common chuckwalla measures 15 3/4 inches long, whereas insular species such as the San Esteban chuckwalla of San Esteban Island can measure as long as 30 in. They are sexually dimorphic, with males having reddish-pink to orange, yellow, or light gray bodies and black heads and limbs. Males are larger than females and possess well-developed femoral pores located on the inner sides of their thighs.
The genus Sauromalus has a wide distribution in biomes of the Mojave Deserts. The common chuckwalla is the species with the greatest range, found from southern California east to southern Nevada and Utah and western Arizona, south to Baja California and northwestern Mexico; the peninsular chuckwalla is found on the eastern portion of the southern half of the Baja California Peninsula. The other species are island-dwelling; the Angel Island chuckwalla is found on Isla Ángel de la Guarda and surrounding islands off the coast of the Baja California Peninsula. Two rare and endangered species are the Montserrat chuckwalla found on Islas Carmen and Montserrat in the southern Gulf of California and the San Esteban chuckwalla or painted chuckwalla found on San Esteban Island and Pelicanos. Chuckwallas prefer lava flows and rocky areas vegetated by creosote bush and other such drought-tolerant scrub; the lizards may be found at elevations up to 4,500 ft. Herbivorous, chuckwallas feed on leaves and flowers of annuals and perennial plants.
The lizards are said to prefer yellow flowers, such as those of the brittlebush. Harmless to humans, these lizards are known to run from potential threats; when disturbed, a chuckwalla wedges itself into a tight rock crevice and inflates its lungs to entrench itself. Males are conditionally territorial. Chuckwallas use a combination of color and physical displays, namely "push-ups", head-hobbing, gaping of the mouth, to communicate and defend their territory. Chuckwallas are diurnal animals and as they are ectothermic, spend much of their mornings and winter days basking; these lizards are well adapted to desert conditions. Juveniles emerge first adults, as temperatures reach around 90 °F. Chuckwallas hibernate during cooler months and emerge in February. Mating occurs from April with five to 16 eggs laid between June and August; the eggs hatch in late September. Chuckwallas may live for 25 years or more; the Comca’ac considered the Angel Island species of chuckwalla an important food item. They are believed to have translocated the lizards to most of the islands in Bahia de los Angeles for use as a food source in times of need.
ARKive - images and movies of the San Esteban Island chuckwalla www.chuckwalla-reptiles-tirol.at https://www.facebook.com/groups/555917997826565/