Gila monster

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Gila monster
Gila monster2.JPG
Scientific classification Red Pencil Icon.png
Kingdom: Animalia
Phylum: Chordata
Class: Reptilia
Order: Squamata
Family: Helodermatidae
Genus: Heloderma
Species:
H. suspectum
Binomial name
Heloderma suspectum
Cope, 1869
Gila monster

The Gila monster (Heloderma suspectum, /ˈhlə/ HEE-lə) is a species of venomous lizard native to the southwestern United States and northwestern Mexican state of Sonora. A heavy, typically slow-moving lizard, up to 60 cm (2.0 ft) long, the Gila monster is the only venomous lizard native to the United States and one of only two known species of venomous lizards in North America, the other being its close relative, the Mexican beaded lizard (H. horridum). [2] Although the Gila monster is venomous, its sluggish nature means it represents little threat to humans. However, it has acquired a fearsome reputation, and is sometimes killed despite being protected by state law in Arizona. [1] [3] In 2019, the state of Utah made the Gila monster its official state reptile. [4]

Venom form of toxin secreted by an animal for the purpose of causing harm to another; poisonous substance injected by animals into a victim

Venom is a secretion containing one or more toxins produced by an animal to cause harm to another. Venom has evolved in a wide variety of animals, both predators and prey, and both vertebrates and invertebrates.

Lizard suborder of reptiles

Lizards are a widespread group of squamate reptiles, with over 6,000 species, ranging across all continents except Antarctica, as well as most oceanic island chains. The group is paraphyletic as it excludes the snakes and Amphisbaenia; some lizards are more closely related to these two excluded groups than they are to other lizards. Lizards range in size from chameleons and geckos a few centimeters long to the 3 meter long Komodo dragon.

Contents

History

Gila monster is the largest extant lizard native to North America north of the Mexican border (non-natives like green iguanas are larger). Its snout-to-vent length is 26 to 36 cm (10 to 14 in). The tail is about 20% of the body size and the largest specimens may reach 51 to 56 cm (20 to 22 in) in total length. Body mass is typically in the range of 350 to 700 g (0.77 to 1.54 lb), with 11 males having been found to average 468 g (1.032 lb). Reportedly the very largest specimens can weigh as much as 2,300 g (5.1 lb). [5] [6] [7]

North America Continent entirely within the Northern Hemisphere and almost all within the Western Hemisphere

North America is a continent entirely within the Northern Hemisphere and almost all within the Western Hemisphere. It is also considered by some to be a northern subcontinent of the Americas. 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, and to the southeast by South America and the Caribbean Sea.

Green iguana species of reptile

The green iguana, also known as the American iguana, is a large, arboreal, mostly herbivorous species of lizard of the genus Iguana. Usually, this animal is simply called the iguana. The green iguana ranges over a large geographic area; it is native from southern Brazil and Paraguay as far north as Mexico and the Caribbean islands, and have been introduced from South America to Puerto Rico and are very common throughout the island, where they are colloquially known as gallina de palo and considered an invasive species; in the United States feral populations also exist in South Florida, Hawaii, the U.S. Virgin Islands and the Rio Grande Valley of Texas.

The Gila monster has one close living relative, the beaded lizard (H. horridum), as well as many extinct relatives in the Helodermatidae, the evolutionary history of which may be traced back to the Cretaceous period. The genus Heloderma has existed since the Miocene, when H. texana lived, and fragments of osteoderms from the Gila monster have been found in late Pleistocene (10,000–8,000 years ago) deposits near Las Vegas, Nevada. Because the helodermatids have remained relatively unchanged morphologically, they are occasionally regarded as living fossils. [8] Although the Gila monster appears closely related to the monitor lizards (varanids) of Africa, Asia and Australia, their wide geographical separation and the unique features not found in the varanids indicate the Gila monster is better placed in a separate family. [9]

The Cretaceous is a geologic period and system that spans 79 million years from the end of the Jurassic Period 145 million years ago (mya) to the beginning of the Paleogene Period 66 mya. It is the last period of the Mesozoic Era, and the longest period of the Phanerozoic Eon. The Cretaceous Period is usually abbreviated K, for its German translation Kreide.

The Miocene is the first geological epoch of the Neogene Period and extends from about 23.03 to 5.333 million years ago (Ma). The Miocene was named by Charles Lyell; its name comes from the Greek words μείων and καινός and means "less recent" because it has 18% fewer modern sea invertebrates than the Pliocene. The Miocene is preceded by the Oligocene and is followed by the Pliocene.

Osteoderm

Osteoderms are bony deposits forming scales, plates or other structures based in the dermis. Osteoderms are found in many groups of extant and extinct reptiles and amphibians, including lizards, crocodilians, frogs, temnospondyls, various groups of dinosaurs, phytosaurs, aetosaurs, placodonts, and hupehsuchians.

Plate from the Century Cyclopedia depicts the Gila monster Gila monster ncd 2012.jpg
Plate from the Century Cyclopedia depicts the Gila monster

The name "Gila" refers to the Gila River Basin in the U.S. states of New Mexico and Arizona, where the Gila monster was once plentiful. [10] Heloderma means "studded skin", from the Ancient Greek words helos (ἧλος), "the head of a nail or stud", and derma (δέρμα), "skin". Suspectum comes from the describer, paleontologist Edward Drinker Cope, who suspected the lizard might be venomous due to the grooves in the teeth. [8]

Gila River river in the United States of America

The Gila River is a 649-mile (1,044 km) tributary of the Colorado River flowing through New Mexico and Arizona in the United States. The river drains an arid watershed of nearly 60,000 square miles (160,000 km2) that lies mainly within the U.S. but also extends into northern Sonora, Mexico. Indigenous peoples have lived along the river for at least 2,000 years, establishing complex agricultural societies before European exploration of the region began in the 16th century. However, European Americans did not permanently settle the Gila River watershed until the mid-19th century.

New Mexico State of the United States of America

New Mexico is a state in the Southwestern region of the United States of America; its capital and cultural center is Santa Fe, which was founded in 1610 as capital of Nuevo México, while its largest city is Albuquerque with its accompanying metropolitan area. It is one of the Mountain States and shares the Four Corners region with Utah, Colorado, and Arizona; its other neighboring states are Oklahoma to the northeast, Texas to the east-southeast, and the Mexican states of Chihuahua to the south and Sonora to the southwest. With a population around two million, New Mexico is the 36th state by population. With a total area of 121,592 sq mi (314,920 km2), it is the fifth-largest and sixth-least densely populated of the 50 states. Due to their geographic locations, northern and eastern New Mexico exhibit a colder, alpine climate, while western and southern New Mexico exhibit a warmer, arid climate.

Arizona state of the United States of America

Arizona is a state in the southwestern region of the United States. It is also part of the Western and the Mountain states. It is the sixth largest and the 14th most populous of the 50 states. Its capital and largest city is Phoenix. Arizona shares the Four Corners region with Utah, Colorado, and New Mexico; its other neighboring states are Nevada and California to the west and the Mexican states of Sonora and Baja California to the south and southwest.

Distribution and habitat

Head with bead-like scales and strong forelegs and claws suitable for digging Gila Monster head.jpg
Head with bead-like scales and strong forelegs and claws suitable for digging

The Gila monster is found in the Southwestern United States and Mexico, a range including Sonora, Arizona, parts of California, Nevada, Utah, and New Mexico (potentially including Baja California). They inhabit scrubland, succulent desert, and oak woodland, seeking shelter in burrows, thickets, and under rocks in locations with ready access to moisture. [11] In fact, Gila monsters seem to like water and can be observed immersing themselves in puddles of water after a summer rain. [12] They avoid living in open areas such as flats and farmland. [13]

Southwestern United States Geographical region of the USA

The Southwestern United States, also known as the American Southwest, is the informal name for a region of the western United States. Definitions of the region's boundaries vary a great deal and have never been standardized, though many boundaries have been proposed. For example, one definition includes the stretch from the Mojave Desert in California to Carlsbad, New Mexico, and from the Mexico–United States border to the southern areas of Colorado, Utah, and Nevada. The largest metropolitan areas are centered around Phoenix, Las Vegas, Tucson, Albuquerque, and El Paso. Those five metropolitan areas have an estimated total population of more than 9.6 million as of 2017, with nearly 60 percent of them living in the two Arizona cities—Phoenix and Tucson.

Sonora State of Mexico

Sonora, officially Estado Libre y Soberano de Sonora, is one of 31 states that, with Mexico City, comprise the 32 federal entities of United Mexican States. It is divided into 72 municipalities; the capital city is Hermosillo. Sonora is bordered by the states of Chihuahua to the east, Baja California to the northwest and Sinaloa to the south. To the north, it shares the U.S.–Mexico border primarily with the state of Arizona with a small length with New Mexico, and on the west has a significant share of the coastline of the Gulf of California.

California State of the United States of America

California is a state in the Pacific Region of the United States. With 39.6 million residents, California is the most populous U.S. state and the third-largest by area. The state capital is Sacramento. The Greater Los Angeles Area and the San Francisco Bay Area are the nation's second- and fifth-most populous urban regions, with 18.7 million and 9.7 million residents respectively. Los Angeles is California's most populous city, and the country's second-most populous, after New York City. California also has the nation's most populous county, Los Angeles County, and its largest county by area, San Bernardino County. The City and County of San Francisco is both the country's second-most densely populated major city after New York City and the fifth-most densely populated county, behind only four of the five New York City boroughs.

Ecology

Gila monsters spend 90% of their time underground in burrows or rocky shelters.[ citation needed ] They are active in the morning during the dry season (spring and early summer); later in the summer, they may be active on warm nights or after a thunderstorm. They maintain a surface body temperature of about 30 °C (86 °F). [14] Gila monsters are slow in sprinting ability, but they have relatively high endurance and maximal aerobic capacity (VO2 max) for a lizard. [15] They are preyed upon by coyotes and raptors.

Thunderstorm type of weather

A thunderstorm, also known as an electrical storm or a lightning storm, is a storm characterized by the presence of lightning and its acoustic effect on the Earth's atmosphere, known as thunder. Relatively weak thunderstorms are sometimes called thundershowers. Thunderstorms occur in a type of cloud known as a cumulonimbus. They are usually accompanied by strong winds, and often produce heavy rain and sometimes snow, sleet, or hail, but some thunderstorms produce little precipitation or no precipitation at all. Thunderstorms may line up in a series or become a rainband, known as a squall line. Strong or severe thunderstorms include some of the most dangerous weather phenomena, including large hail, strong winds, and tornadoes. Some of the most persistent severe thunderstorms, known as supercells, rotate as do cyclones. While most thunderstorms move with the mean wind flow through the layer of the troposphere that they occupy, vertical wind shear sometimes causes a deviation in their course at a right angle to the wind shear direction.

Diet

The Gila monster eats small birds, mammals, frogs, smaller lizards, insects, and carrion. [16] The Gila monster feeds primarily on bird and reptile eggs, and eats infrequently (only five to ten times a year in the wild), [17] but when it does feed, it may eat up to one-third of its body mass. [5] It uses its extremely acute sense of smell to locate prey, especially eggs. Its sense of smell is so keen, it can locate and dig up chicken eggs buried 15 cm (6 in) deep and accurately follow a trail made by a rolling egg. [9]

Prey may be crushed to death if large or eaten alive if small, swallowed head-first, and helped down by muscular contractions and neck flexing. Unusually, after food has been swallowed, the Gila monster immediately resumes tongue flicking and search behavior, probably as a result of a history of finding clumped prey such as eggs and young in nests. [14] Gila monsters are able to climb trees and cacti in search of eggs. [18]

Venom

I have never been called to attend a case of Gila monster bite, and I don't want to be. I think a man who is fool enough to get bitten by a Gila monster ought to die. The creature is so sluggish and slow of movement that the victim of its bite is compelled to help largely in order to get bitten.

Pioneer beliefs

In the Old West, the pioneers believed a number of myths about the Gila monster, including that the lizard had foul or toxic breath and that its bite was fatal. [19] The Tombstone Epitaph of Tombstone, Arizona, wrote about a Gila monster that a local person caught on May 14, 1881:

This is a monster, and no baby at that, it being probably the largest specimen ever captured in Arizona. It is 27 inches long and weighs 35 lb. It was caught by H. C. Hiatt on the road between Tombstone and Grand Central Mill and was purchased by Messrs. Ed Baker and Charles Eastman, who now have it on exhibition at Kelley's Wine House, next door above Grand Hotel, Allen Street. Eastern people who have never seen one of these monsters should not fail to inspect his Aztecship, for they might accidentally stumble upon one some fine day and get badly frightened, except they know what it is. [19]

On May 8, 1890, southeast of Tucson, Arizona Territory, Empire Ranch owner Walter Vail captured and thought he had killed a Gila monster. He tied it to his saddle and it bit the middle finger of his right hand and wouldn't let go. A ranch hand pried open the lizard's mouth with a pocketknife, cut open his finger to stimulate bleeding, and then tied saddle strings around his finger and wrist. They summoned Dr. John C. Handy of Tucson, who took Vail back to Tucson for treatment, but Vail experienced swollen and bleeding glands in his throat for sometime afterward. [19]

Dr. Handy's friend, Dr. George Goodfellow of Tombstone, was among the first to research the actual effects of Gila monster venom. Scientific American reported in 1890 that "The breath is very fetid, and its odor can be detected at some little distance from the lizard. It is supposed that this is one way in which the monster catches the insects and small animals which form a part of its food supply—the foul gas overcoming them." Goodfellow offered to pay local residents $5.00 for Gila monster specimens. He bought several and collected more on his own. In 1891 he purposefully provoked one of his captive lizards into biting him on his finger. The bite made him ill and he spent the next five days in bed, but he completely recovered. When Scientific American ran another ill-founded report on the lizard's ability to kill people, he wrote in reply and described his own studies and personal experience. He wrote that he knew several people who had been bitten by Gila monsters but had not died from the bite. [19]

Goodfellow published articles about rattlesnake and Gila monster bites in Scientific American and Southern California Practitioner. [20]

Delivery

The Gila monster produces venom in modified salivary glands in its lower jaw, unlike snakes, whose venom is produced in the upper jaw. [16] The Gila monster lacks the musculature to forcibly inject the venom; instead, the venom is propelled from the gland to the tooth by chewing. Capillary action brings the venom out of the tooth and into the victim. [8] The teeth are loosely anchored, which allows them to be broken off and replaced throughout life. Gila monsters have been observed to flip over while biting the victim, presumably to aid the flow of the venom into the wound. Because the Gila monster's prey consists mainly of eggs, small animals, and otherwise "helpless" prey, the Gila monster's venom is thought to have evolved for defensive rather than for hunting use. A defensive use would explain the Gila monster's bright warning coloration. [9]

Toxicity

A reticulated Gila monster (H. s. suspectum) Reticulate Gila Monster.jpg
A reticulated Gila monster (H. s. suspectum)

Although the venom is about as toxic as a Western diamondback rattlesnake, H. suspectum produces only small amounts. [13] The Gila monster's bite is not fatal to healthy adult humans. [19] No reports of fatalities have been confirmed after 1939, and those recorded prior to that year are youngsters, or resulting from failed attempts to treat the bite itself. [ citation needed ] The Gila monster can bite quickly (especially by swinging its head sideways) and hold on tenaciously and painfully. [14] If bitten, the victim may need to fully submerge the attacking lizard in water to break free from its bite or physically yank the lizard free, risking severe lacerations in the process from the lizard's sharp teeth. Symptoms of the bite include excruciating pain, edema, and weakness associated with a rapid drop in blood pressure. One zoological journalist, when giving a report about the pain of a bite, described it as "the worst pain [he] had ever experienced ... it's like hot lava coursing through your veins". It is generally regarded as the most painful venom produced by any vertebrate. [21]

More than a dozen peptides and other substances have been isolated from the Gila monster's venom, including hyaluronidase, serotonin, phospholipase A2, and several kallikrein-like glycoproteins responsible for the pain and edema caused by a bite. Four potentially lethal toxins have been isolated from the Gila monster's venom, including horridum venom, which causes hemorrhage in internal organs and exophthalmos (bulging of the eyes), [22] and helothermine, which causes lethargy, partial paralysis of the limbs, and hypothermia in rats. Most are similar in form to vasoactive intestinal peptide (VIP), which relaxes smooth muscle and regulates water and electrolyte secretion between the small and large intestines. These bioactive peptides are able to bind to VIP receptors in many different human tissues. One of these, helodermin, has been shown to inhibit the growth of lung cancer. [8] [23] [24]

The constituents of the lizard's venom that have received the most attention from researchers are the bioactive peptides, including helodermin, helospectin, exendin-3, and exendin-4. [25] Exendin-4 has formed the basis of a class of medications for the treatment of type 2 diabetes, known as Glucagon-like peptide-1 agonists. Exenatide was the first product in the class to reach the market and was launched in 2005.

Drug research

In 2005, the US Food and Drug Administration approved the drug exenatide (marketed as Byetta) for the management of type 2 diabetes. It is a synthetic version of a protein, exendin-4, derived from the Gila monster's saliva. [26] In a three-year study with people with type 2 diabetes, exenatide led to healthy sustained glucose levels and progressive weight loss. The effectiveness is because the lizard protein is about 50% identical to glucagon-like peptide-1 analog (GLP-1), a hormone released from the human digestive tract that helps to regulate insulin and glucagon. The lizard protein remains effective much longer than the human hormone, helping diabetics keep their blood sugar levels under control. Exenatide slows the emptying of the stomach and causes a decrease in appetite, contributing to weight loss. [27]

The saliva of the Gila monster contains many chemicals which can be deadly. One of these has been shown to affect memory. Several companies have been researching the abilities of this chemical to help memory loss due to various diseases such as Alzheimer's disease, schizophrenia, and ADHD. Gilatide, derived from exendin-4, has been shown to dramatically heighten memory in a study with mice. Gilatide is likely to be researched further to provide help to Alzheimer's patients.

Life history

Gila monster at the Bristol Zoo Gila.monster.arp.jpg
Gila monster at the Bristol Zoo

The Gila monster emerges from hibernation in January or February and mates in May and June. [16] The male initiates courtship by flicking his tongue to search for the female's scent. If the female rejects his advances, she will bite him and crawl away. When successful, copulation has been observed to last from 15 minutes to as long as two and a half hours. The female lays eggs in July or August, burying them in sand 5 in (13 cm) below the surface. The clutch consists of two to 12 eggs: five is the average. [11] The incubation lasts nine months, as the hatchlings emerge during April through June the following year. [28] The hatchlings are about 16 cm (6.3 in) long and can bite and inject venom upon hatching. The juveniles typically have larger bands of pink scales than adults, although the banded Gila monster (H. s. cinctum) has a tendency to retain the band pattern. H. suspectum sexually matures at three to five years old. After egg-laying, adult Gila monsters gradually spend less time on the surface to avoid the hottest part of the summer (although they may be active in the evening), eventually starting their hibernation around November. [9]

Little is known about the social behavior of H. suspectum, but they have been observed engaging in male-male combat, in which the dominant male lies on top of the subordinate one and pins it with its front and hind limbs. Both lizards arch their bodies, pushing against each other and twisting around in an effort to gain the dominant position. A wrestling match ends when the pressure exerted forces them to separate, although bouts may be repeated one after the other. These bouts are typically observed just before the mating season. Those with greater strength and endurance are thought to win more often and enjoy greater reproductive success. [29] Although the Gila monster has a low metabolism and one of the lowest lizard sprint speeds, it has one of the highest aerobic scope values (the increase in oxygen consumption from rest to maximum metabolic exertion) among lizards, allowing them to engage in intense aerobic activity for a sustained period of time. Males have been observed to have higher aerobic scopes than females, presumably because of sexual selection for a trait advantageous in prolonged combat. [15] The Gila monster may live up to 20 years in the wild, or 30 in captivity. [30]

Conservation status

Urban sprawl and habitat destruction have adversely affected Gila monster numbers. In 1952, they became the first venomous animal to be given legal protection. [12] [31] [32] Gila monsters are listed as Near Threatened by the IUCN. [1] In 1963, the San Diego Zoo became the first zoo to successfully breed Gila monsters in captivity. [30]

Relationship with humans

Though the Gila monster is venomous, its laggard movement means it poses little threat to humans. However, it has a fearsome reputation and is often killed by humans. Among Native American tribes, the Gila monster had a mixed standing. The Apache believed its breath could kill a man, and the Tohono O'Odham and the Pima believed it possessed a spiritual power that could cause sickness. In contrast, the Seri and the Yaqui believed the Gila monster's hide had healing properties. [13]

The Gila monster has even starred as a monster in the film The Giant Gila Monster (though the titular monster was actually portrayed by a Mexican beaded lizard). [33] It played a minor role in the motion picture The Treasure of the Sierra Madre. In Brock Brower's 1971 novel The Late Great Creature fictional horror movie star Simon Moro is presented as famous for playing the reptilian werewolf-like Gila Man.

Myths about the animal include that the animal's breath is toxic enough to kill humans, that it can spit venom like a spitting cobra and that it can leap several feet in the air to attack. [30] Another myth held that the Gila monster did not have an anus and therefore expelled waste from its mouth, the source of its venom and "fetid breath". [14]

The official mascot of Eastern Arizona College located in Thatcher, Arizona, is Gila Hank, a gun-toting, cowboy-hat-wearing Gila monster. A similar character as an old western outlaw was seen in 2011 animated film Rango , called Bad Bill; the character was voiced by Ray Winstone. [34] In 2017, the Vegas Golden Knights selected a Gila monster, named Chance, as the official mascot. [35]

Related Research Articles

Squamata Order of reptiles

Squamata is the largest order of reptiles, comprising lizards, snakes and amphisbaenians, which are collectively known as squamates or scaled reptiles. With over 10,000 species, it is also the second-largest order of extant (living) vertebrates, after the perciform fish, and roughly equal in number to the Saurischia. Members of the order are distinguished by their skins, which bear horny scales or shields. They also possess movable quadrate bones, making it possible to move the upper jaw relative to the neurocranium. This is particularly visible in snakes, which are able to open their mouths very wide to accommodate comparatively large prey. Squamata is the most variably sized order of reptiles, ranging from the 16 mm (0.63 in) dwarf gecko to the 5.21 m (17.1 ft) green anaconda and the now-extinct mosasaurs, which reached lengths of over 14 m (46 ft).

Earless monitor lizard Earless monitor lizard

The earless monitor lizard is a semiaquatic, brown lizard native to the Southeast Asian island of Borneo. It is the only living species in the family Lanthanotidae and it is related to the true monitor lizards.

<i>Heloderma</i> genus of reptiles

Heloderma, or beaded lizards, are large, stocky, slow-moving reptiles that prefer semi-arid climates. Their tails are short and used as fat storage organs. They are covered with small, non-overlapping, bead-like scales, with osteoderms on the undersides of their bodies. All species are dark in color, with yellowish or pinkish markings. Heloderma is the only living genus of the family Helodermatidae.

Rattlesnake Group of venomous snakes of the genera Crotalus and Sistrurus

Rattlesnakes are a group of venomous snakes of the genera Crotalus and Sistrurus of the subfamily Crotalinae. The scientific name Crotalus is derived from the Greek κρόταλον, meaning "castanet". The name Sistrurus is the Latinized form of the Greek word for "tail rattler" and shares its root with the ancient Egyptian musical instrument the sistrum, a type of rattle. The 36 known species of rattlesnakes have between 65 and 70 subspecies, all native to the Americas, ranging from southern Alberta and Saskatchewan and southern British Columbia in Canada to central Argentina.

Viperidae family of reptiles

The Viperidae (vipers) are a family of venomous snakes found in most parts of the world, with the exception of Antarctica, Australia, Hawaii, Madagascar, New Zealand, various other isolated islands, and north of the Arctic Circle. All have relatively long, hinged fangs that permit deep penetration and injection of snake venom. Four subfamilies are currently recognized. They are also known as viperids. The name "viper" is derived from the Latin word vipera, -ae, also meaning viper, possibly from vivus ("living") and parere, referring to the trait viviparity common in vipers but not in snakes at large.

Goanna

A goanna is any of several Australian monitor lizards of the genus Varanus, as well as certain species from Southeast Asia.

Envenomation is the process by which venom is injected by the bite or sting of a venomous animal.

Perentie species of reptile

The perentie is the largest monitor lizard or goanna native to Australia, and the fourth-largest living lizard on earth, after the Komodo dragon, Asian water monitor, and the crocodile monitor. Found west of the Great Dividing Range in the arid areas of Australia, it is rarely seen because of its shyness and the remoteness of much of its range from human habitation. The species is considered to be a least-concern species according to the International Union for Conservation of Nature (IUCN)

Mexican beaded lizard species of reptile

The Mexican beaded lizard is a species of lizard in the family Helodermatidae, one of the two species of venomous beaded lizards found principally in Mexico and southern Guatemala. It and its congener the Gila monster are the only lizards known to have evolved an overt venom delivery system. The Mexican beaded lizard is larger than the Gila monster, with duller coloration, black with yellowish bands. As it is a specialized predator that feeds primarily upon eggs, the primary use of its venom is still a source of debate among scientists. However, this venom has been found to contain several enzymes useful for manufacturing drugs in the treatment of diabetes, and research on the pharmacological use of its venom is ongoing.

Toxicofera Proposed clade of scaled reptiles

Toxicofera is a proposed clade of scaled reptiles (squamates) that includes the Serpentes (snakes), Anguimorpha and Iguania. Toxicofera contains about 4,600 species, of extant squamata. It encompasses all venomous reptile species, as well as numerous related non-venomous species. There is little morphological evidence to support this grouping, however it has been recovered by all recent molecular analyses.

Desert monitor species of reptile

The desert monitor, Varanus griseus, is a species of monitor lizards of the order Squamata found living throughout North Africa and Central and South Asia. Three subspecies have been described:

Venomous snakes are species of the suborder Serpentes that are capable of producing venom, which they use for killing prey, for defense, and to assist with digestion of their prey. The venom is typically delivered by injection using hollow or grooved fangs, although some venomous snakes lack well-developed fangs. Common venomous snakes include the families Elapidae, Viperidae, Atractaspididae, and some of the Colubridae. The toxicity of venom is mainly indicated by murine LD50, while multiple factors are considered to judge the potential danger to humans. Other important factors for risk assessment include the likelihood that a snake will bite, the quantity of venom delivered with the bite, the efficiency of the delivery mechanism, and the location of a bite on the body of the victim. Snake venom may have both neurotoxic and hemotoxic properties.

Mamushi species of snake

Gloydius blomhoffii, commonly known as the mamushi, Japanese moccasin, Japanese pit viper, Qichun snake or Japanese mamushi, is a venomous pitviper species found in China, Japan, and Korea. There are four subspecies including the nominate subspecies described here.

<i>Heloderma charlesbogerti</i> species of reptile

The Guatemalan beaded lizard, also called the Motagua Valley beaded lizard, is a highly endangered species of beaded lizard, a venomous lizard endemic to the dry forests of the Motagua Valley in southeastern Guatemala, an ecoregion known as the Motagua Valley thornscrub. It is the only allopatric beaded lizard species, separated from the nearest population by 250 km of unsuitable habitat. The Guatemalan beaded lizard is the rarest and most endangered species of beaded lizard and it is believed that fewer than 200 of these animals exist in the wild, making it one of the most endangered lizards in the world. In 2007, it was transferred from Appendix II to Appendix I of CITES due to its critical conservation status.

Uatchitodon is an extinct genus of Late Triassic reptile known only from isolated teeth. Based on the structure of the teeth, Uatchitodon was probably a carnivorous archosauromorph. Folded grooves on the teeth indicate that the animal was likely venomous, with the grooves being channels for salivary venom. The teeth are similar to those of living venomous squamates such as Heloderma and venomous snakes. Uatchitodon is the earliest known venomous reptile.

Helothermine is a toxin from the venom of the Mexican beaded lizard Heloderma horridum horridum. Helothermine inhibits ryanodine receptors, calcium channels and potassium channels. Helothermine can cause lethargy, partial paralysis of rear limbs and lowering of the body temperature.

Venom in medicine is the medicinal use of venoms for therapeutic benefit in treating diseases.

References

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  2. Fry, Bryan G.; et al. (February 2006). "Early evolution of the venom system in lizards and snakes". Nature. 439 (7076): 584–588. doi:10.1038/nature04328. PMID   16292255 . Retrieved 2008-05-14.
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Further reading