67-437: Vipers are snakes in the family Viperidae , found in most parts of the world, except for Antarctica , Australia , Hawaii , Madagascar , New Zealand , Ireland , and various other isolated islands. They are venomous and have long (relative to non-vipers), hinged fangs that permit deep penetration and injection of their venom . Three subfamilies are currently recognized. They are also known as viperids . The name "viper"
134-409: A bite can still result in a permanent scar , and in the worst cases, the affected limb may even have to be amputated . A victim's fate is impossible to predict, as this depends on many factors, including the species and size of the snake involved, how much venom was injected (if any), and the size and condition of the patient before being bitten. Viper bite victims may also be allergic to the venom or
201-618: A distinct family group name, despite the fact that Gray was the first to use the form Viperinae. Snake Snakes are elongated, limbless reptiles of the suborder Serpentes ( / s ɜːr ˈ p ɛ n t iː z / ). Like all other squamates , snakes are ectothermic , amniote vertebrates covered in overlapping scales . Many species of snakes have skulls with several more joints than their lizard ancestors, enabling them to swallow prey much larger than their heads ( cranial kinesis ). To accommodate their narrow bodies, snakes' paired organs (such as kidneys) appear one in front of
268-714: A family of giant, primitive, python-like snakes, was around until 50,000 years ago in Australia, represented by genera such as Wonambi . Recent molecular studies support the monophyly of the clades of modern snakes, scolecophidians, typhlopids + anomalepidids, alethinophidians, core alethinophidians, uropeltids ( Cylindrophis , Anomochilus , uropeltines), macrostomatans, booids, boids, pythonids and caenophidians. While snakes are limbless reptiles, evolved from (and grouped with) lizards, there are many other species of lizards that have lost their limbs independently but which superficially look similar to snakes. These include
335-484: A marine way of life in different ways and to various degrees. All have evolved paddle-like tails for swimming and the ability to excrete salt. Most also have laterally compressed bodies, their ventral scales are much reduced in size, their nostrils are located dorsally (no internasal scales ), and they give birth to live young ( viviparity ). The reduction in ventral scaling has greatly diminished their terrestrial mobility, but aids in swimming. Members of this family have
402-661: A minor component of the North American fauna, but during the Miocene, the number of species and their prevalence increased dramatically with the first appearances of vipers and elapids in North America and the significant diversification of Colubridae (including the origin of many modern genera such as Nerodia , Lampropeltis , Pituophis , and Pantherophis ). There is fossil evidence to suggest that snakes may have evolved from burrowing lizards, during
469-435: A pair of proteroglyphous fangs to inject venom from glands located towards the rear of the upper jaw (except for the genus Emydocephalus , in which fangs are present as a vestigial feature but without venom production, as they have specialized toward a fish egg diet, making them the only non-venomous elapids). The fangs, which are enlarged and hollow, are the first two teeth on each maxillary bone. Usually only one fang
536-414: A positive cladistical correlation, although some of these features are shared with varanids. Genetic studies in recent years have indicated snakes are not as closely related to monitor lizards as was once believed—and therefore not to mosasaurs, the proposed ancestor in the aquatic scenario of their evolution. However, more evidence links mosasaurs to snakes than to varanids. Fragmented remains found from
603-520: A short tail remains of the caudal vertebrae. However, the tail is still long enough to be of important use in many species, and is modified in some aquatic and tree-dwelling species. Many modern snake groups originated during the Paleocene , alongside the adaptive radiation of mammals following the extinction of (non-avian) dinosaurs . The expansion of grasslands in North America also led to an explosive radiation among snakes. Previously, snakes were
670-415: A short time. In predatory bites, factors that influence the amount of venom injected include the size of the prey, the species of prey, and whether the prey item is held or released. The need to label prey for chemosensory relocation after a bite and release may also play a role. In defensive bites, the amount of venom injected may be determined by the size or species of the predator (or antagonist), as well as
737-476: A wide range of light levels. Typically, vipers are nocturnal and ambush their prey . Compared to many other snakes, vipers often appear rather sluggish. Most are ovoviviparous : the eggs are retained inside the mother's body, and the young emerge living. However, a few lay eggs in nests. Typically, the number of young in a clutch remains constant, but as the weight of the mother increases, larger eggs are produced, yielding larger young. Viperid snakes are found in
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#1732772130401804-441: A wide range of sizes. Drysdalia species are small serpents typically 50 cm (20 in) and down to 18 cm (7.1 in) in length. Cobras , mambas , and taipans are mid- to large sized snakes which can reach 2 m (6 ft 7 in) or above. The king cobra is the world's longest venomous snake with a maximum length of 5.85 m (19.2 ft) and an average mass of 6 kg (13 lb). All elapids have
871-470: Is a family of snakes characterized by their permanently erect fangs at the front of the mouth. Most elapids are venomous , with the exception of the genus Emydocephalus . Many members of this family exhibit a threat display of rearing upwards while spreading out a neck flap. Elapids are endemic to tropical and subtropical regions around the world, with terrestrial forms in Asia, Australia, Africa, and
938-420: Is a finer one, barely visible; the cavities are connected internally, separated only by a membrane with nerves that are extraordinarily attuned to detecting temperature changes between. As in the overlapping vision fields of human eyes, the forward-facing pit on either side of the face combined produces a field of vision: a pit viper can distinguish between objects and their environments, as well as accurately judge
1005-415: Is adapted for burrowing and its stomach indicates that it was preying on other animals. It is currently uncertain if Tetrapodophis is a snake or another species, in the squamate order, as a snake-like body has independently evolved at least 26 times. Tetrapodophis does not have distinctive snake features in its spine and skull. A study in 2021 places the animal in a group of extinct marine lizards from
1072-534: Is also dual-purpose: first, it is used for defense and to immobilize prey, as with neurotoxic venoms; second, many of the venom's enzymes have a digestive function, breaking down molecules such as lipids , nucleic acids , and proteins. This is an important adaptation, as many vipers have inefficient digestive systems. Due to the nature of proteolytic venom, a viperid bite is often a very painful experience and should always be taken seriously, though it may not necessarily prove fatal. Even with prompt and proper treatment,
1139-476: Is associated with DNA mutations in the Zone of Polarizing Activity Regulatory Sequence (ZRS), a regulatory region of the sonic hedgehog gene which is critically required for limb development. More advanced snakes have no remnants of limbs, but basal snakes such as pythons and boas do have traces of highly reduced, vestigial hind limbs. Python embryos even have fully developed hind limb buds, but their later development
1206-461: Is based on morphological characteristics and mitochondrial DNA sequence similarity. Alethinophidia is sometimes split into Henophidia and Caenophidia , with the latter consisting of "colubroid" snakes ( colubrids , vipers , elapids , hydrophiids , and atractaspids ) and acrochordids, while the other alethinophidian families comprise Henophidia. While not extant today, the Madtsoiidae ,
1273-525: Is believed that the Laticauda and the 'true sea snakes' evolved separately from Australasian land snakes. Asian cobras, coral snakes, and American coral snakes also appear to be monophyletic, while African cobras do not. The type genus for the Elapidae was originally Elaps , but the group was moved to another family. In contrast to what is typical of botany , the family Elapidae was not renamed. In
1340-468: Is derived from the Latin word vipera , - ae , also meaning viper, possibly from vivus ("living") and parere ("to beget"), referring to the trait viviparity (giving live birth) common in vipers like most of the species of Boidae . All viperids have a pair of relatively long solenoglyphous (hollow) fangs that are used to inject venom from glands located towards the rear of the upper jaws, just behind
1407-1161: Is in place on each side at any time. The maxilla is intermediate in both length and mobility between typical colubrids (long, less mobile) and viperids (very short, highly mobile). When the mouth is closed, the fangs fit into grooved slots in the buccal floor and usually below the front edge of the eye and are angled backwards; some elapids ( Acanthophis , taipan, mamba, and king cobra) have long fangs on quite mobile maxillae and can make fast strikes. A few species are capable of spraying their venom from forward-facing holes in their fangs for defense, as exemplified by spitting cobras . Most elapids are terrestrial , while some are strongly arboreal (African Pseudohaje and Dendroaspis , Australian Hoplocephalus ). Many species are more or less specialized burrowers (e.g. Ogmodon , Parapistocalamus , Simoselaps , Toxicocalamus , and Vermicella ) in either humid or arid environments. Some species have very generalised diets ( euryphagy ), but many taxa have narrow prey preferences (stenophagy) and correlated morphological specializations, for example feeding almost exclusively on other serpents (especially
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#17327721304011474-459: Is not universal (see Amphisbaenia , Dibamidae , and Pygopodidae ). Living snakes are found on every continent except Antarctica, and on most smaller land masses; exceptions include some large islands, such as Ireland, Iceland, Greenland, and the islands of New Zealand, as well as many small islands of the Atlantic and central Pacific oceans. Additionally, sea snakes are widespread throughout
1541-624: Is potent enough to cause painful injury or death to humans. Nonvenomous snakes either swallow prey alive or kill by constriction . The English word snake comes from Old English snaca , itself from Proto-Germanic * snak-an- ( cf. Germanic Schnake 'ring snake', Swedish snok 'grass snake'), from Proto-Indo-European root * (s)nēg-o- 'to crawl to creep', which also gave sneak as well as Sanskrit nāgá 'snake'. The word ousted adder , as adder went on to narrow in meaning, though in Old English næddre
1608-585: Is relatively poor because snake skeletons are typically small and fragile making fossilization uncommon. Fossils readily identifiable as snakes (though often retaining hind limbs) first appear in the fossil record during the Cretaceous period. The earliest known true snake fossils (members of the crown group Serpentes) come from the marine simoliophiids , the oldest of which is the Late Cretaceous ( Cenomanian age) Haasiophis terrasanctus from
1675-816: Is stopped by the DNA mutations in the ZRS. There are about 3,900 species of snakes, ranging as far northward as the Arctic Circle in Scandinavia and southward through Australia. Snakes can be found on every continent except Antarctica, as well as in the sea, and as high as 16,000 feet (4,900 m) in the Himalayan Mountains of Asia. There are numerous islands from which snakes are absent, such as Ireland , Iceland , and New Zealand (although New Zealand's northern waters are infrequently visited by
1742-477: The Colubridae ; almost all have long, slender bodies with smooth scales, a head covered with large shields (and not always distinct from the neck), and eyes with rounded pupils. Also like colubrids, their behavior is usually quite active and fast, with most of the females being oviparous (egg-layers). Exceptions to these generalizations occur; for example, certain adders ( Acanthophis ) have commonalities with
1809-479: The Cretaceous Period . An early fossil snake relative, Najash rionegrina , was a two-legged burrowing animal with a sacrum , and was fully terrestrial . Najash , which lived 95 million years ago, also had a skull with several features typical for lizards, but had evolved some of the mobile skull joints that define the flexible skull in most modern snakes. The species did not show any resemblances to
1876-558: The Jurassic and Early Cretaceous indicate deeper fossil records for these groups, which may potentially refute either hypothesis. Both fossils and phylogenetic studies demonstrate that snakes evolved from lizards , hence the question became which genetic changes led to limb loss in the snake ancestor. Limb loss is actually very common in extant reptiles and has happened dozens of times within skinks , anguids , and other lizards. In 2016, two studies reported that limb loss in snakes
1943-632: The Jurassic period, with the earliest known fossils dating to between 143 and 167 Ma ago. The diversity of modern snakes appeared during the Paleocene epoch ( c. 66 to 56 Ma ago, after the Cretaceous–Paleogene extinction event ). The oldest preserved descriptions of snakes can be found in the Brooklyn Papyrus . Most species of snake are nonvenomous and those that have venom use it primarily to kill and subdue prey rather than for self-defense. Some possess venom that
2010-519: The Viperidae family, such as shorter, stout bodies, rough/keeled scales, broad heads, cat-like pupils and ovoviviparous (internal hatchings with live births). Furthermore, they can also be sluggish, ambush predators with partially fragmented head shields, similar to rattlesnakes or Gaboon vipers . Sea snakes (the Hydrophiinae ), sometimes considered to be a separate family, have adapted to
2077-534: The West Bank , dated to between 112 and 94 million years old. Based on genomic analysis it is certain that snakes descend from lizards . This conclusion is also supported by comparative anatomy , and the fossil record. Pythons and boas —primitive groups among modern snakes—have vestigial hind limbs: tiny, clawed digits known as anal spurs , which are used to grasp during mating. The families Leptotyphlopidae and Typhlopidae also possess remnants of
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2144-407: The antivenom . These snakes can decide how much venom to inject depending on the circumstances. The most important determinant of venom expenditure is generally the size of the snake; larger specimens can deliver much more venom. The species is also important, since some are likely to inject more venom than others, may have more venom available, strike more accurately, or deliver a number of bites in
2211-479: The slowworm , glass snake , and amphisbaenians . Leptotyphlopidae Gerrhopilidae Typhlopidae Xenophidiidae Anomalepididae Aniliidae Tropidophiidae Xenopeltidae Loxocemidae Pythonidae Boidae Bolyeridae Xenophidiidae Uropeltidae Anomochilidae Cylindrophiidae Acrochordidae Xenodermidae Pareidae Viperidae Homalopsidae Colubridae Lamprophiidae Elapidae The fossil record of snakes
2278-434: The yellow-bellied sea snake and the banded sea krait ). The now extinct Titanoboa cerrejonensis was 12.8 m (42 ft) in length. By comparison, the largest extant snakes are the reticulated python , measuring about 6.95 m (22.8 ft) long, and the green anaconda , which measures about 5.21 m (17.1 ft) long and is considered the heaviest snake on Earth at 97.5 kg (215 lb). At
2345-607: The Americas and marine forms in the Pacific and Indian Oceans . Members of the family have a wide range of sizes, from the 18 cm (7.1 in) white-lipped snake to the 5.85 m (19 ft 2 in) king cobra . Most species have neurotoxic venom that is channeled by their hollow fangs, and some may contain other toxic components in varying proportions. The family includes 55 genera with around 360 species and over 170 subspecies. Terrestrial elapids look similar to
2412-849: The Americas, Africa, Eurasia, and South Asia. In the Americas, they are native from south of 48°N . In the Old World , viperids are located everywhere except Siberia , Ireland, and north of the Arctic Circle in Norway and Sweden. Wild viperids are not found in Australia . The common adder , a viperid, is the only venomous snake found in Great Britain . Viperid venoms typically contain an abundance of protein -degrading enzymes, called proteases , that produce symptoms such as pain, strong local swelling and necrosis , blood loss from cardiovascular damage complicated by coagulopathy , and disruption of
2479-508: The Cretaceous period known as dolichosaurs and not directly related to snakes. An alternative hypothesis, based on morphology , suggests the ancestors of snakes were related to mosasaurs —extinct aquatic reptiles from the Cretaceous —forming the clade Pythonomorpha . According to this hypothesis, the fused, transparent eyelids of snakes are thought to have evolved to combat marine conditions (corneal water loss through osmosis), and
2546-584: The Hox gene expression in the axial skeleton responsible for the development of the thorax became dominant. As a result, the vertebrae anterior to the hindlimb buds (when present) all have the same thoracic-like identity (except from the atlas , axis , and 1–3 neck vertebrae). In other words, most of a snake's skeleton is an extremely extended thorax. Ribs are found exclusively on the thoracic vertebrae. Neck, lumbar and pelvic vertebrae are very reduced in number (only 2–10 lumbar and pelvic vertebrae are present), while only
2613-631: The IUCN red-list and CITES Apenndix lists. Some of the protected species are: This however does not touch the number of elapidae that are under threat, for instance 9% of elapid sea snakes are threatened with another 6% near-threatened. A rather large road block that stands in the way of more species being put under protection is lack of knowledge of the taxa; many known species have little research done on their behaviors or actual population as they live in very remote areas or live in habitats that are so vast its nearly impossible to conduct population studies, like
2680-803: The Indian Ocean and the south-west Pacific. They occupy coastal waters and shallows, and are common in coral reefs. However, the range of Hydrophis platurus extends across the Pacific to the coasts of Central and South America. Venoms of species in the Elapidae are mainly neurotoxic for immobilizing prey and defense. The main group of toxins are PLA2 and three-finger toxins (3FTx). Other toxic components in some species comprise cardiotoxins and cytotoxins , which cause heart dysfunctions and cellular damage, respectively. Cobra venom also contains hemotoxins that clot or solidify blood. Most members are venomous to varying extents, and some are considered among
2747-527: The Indian and Pacific oceans. Around thirty families are currently recognized, comprising about 520 genera and about 3,900 species . They range in size from the tiny, 10.4 cm-long (4.1 in) Barbados threadsnake to the reticulated python of 6.95 meters (22.8 ft) in length. The fossil species Titanoboa cerrejonensis was 12.8 meters (42 ft) long. Snakes are thought to have evolved from either burrowing or aquatic lizards, perhaps during
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2814-499: The Laticaudinae (sea kraits). Currently, none are universally recognized. Molecular evidence via techniques like karyotyping, protein electrophoretic analyses, immunological distance and DNA sequencing, suggests reciprocal monophyly of two groups: African, Asian, and New World Elapinae versus Australasian and marine Hydrophiinae . The Australian terrestrial elapids are technically 'hydrophiines', although they are not sea snakes. It
2881-412: The ability to detect thermal radiation emitted by warm-blooded animals , helping them better understand their environment. Internally the organ forms a small pit lined with membranes, external and internal, attached to the trigeminal nerve . Infrared light signals the internal membranes, which in turn signal the trigeminal nerve and send the infrared signals to the brain, where they are overlaid onto
2948-484: The assessed level of threat, although larger assailants and higher threat levels may not necessarily lead to larger amounts of venom being injected. Hemotoxic venom takes more time than neurotoxic venom to immobilize prey, so viperid snakes need to track down prey animals after they have been bitten, in a process known as "prey relocalization". Vipers are able to do this via certain proteins contained in their venom. This important adaptation allowed rattlesnakes to evolve
3015-610: The blood-clotting system. Also being vasculotoxic in nature, viperine venom causes vascular endothelial damage and hemolysis . Death is usually caused by collapse in blood pressure. This is in contrast to elapid venoms, which generally contain neurotoxins that disable muscle contraction and cause paralysis. Death from elapid bites usually results from asphyxiation because the diaphragm can no longer contract, but this rule does not always apply; some elapid bites include proteolytic symptoms typical of viperid bites, while some viperid bites produce neurotoxic symptoms. Proteolytic venom
3082-503: The distance between objects and itself. The heat sensing ability of a pit viper is so great that it can react to a difference as small as one third of a degree Fahrenheit. Other infrared-sensitive snakes have multiple, smaller labial pits lining the upper lip, just below the nostrils. Elapid Elapidae ( / ə ˈ l æ p ə d iː / , commonly known as elapids / ˈ ɛ l ə p ə d z / , from Ancient Greek : ἔλαψ élaps , variant of ἔλλοψ éllops "sea-fish")
3149-531: The ears. Some primitive snakes are known to have possessed hindlimbs, but their pelvic bones lacked a direct connection to the vertebrae. These include fossil species like Haasiophis , Pachyrhachis and Eupodophis , which are slightly older than Najash . This hypothesis was strengthened in 2015 by the discovery of a 113-million-year-old fossil of a four-legged snake in Brazil that has been named Tetrapodophis amplectus . It has many snake-like features,
3216-621: The external ears were lost through disuse in an aquatic environment. This ultimately led to an animal similar to today's sea snakes . In the Late Cretaceous , snakes recolonized land, and continued to diversify into today's snakes. Fossilized snake remains are known from early Late Cretaceous marine sediments, which is consistent with this hypothesis; particularly so, as they are older than the terrestrial Najash rionegrina . Similar skull structure, reduced or absent limbs, and other anatomical features found in both mosasaurs and snakes lead to
3283-408: The eyes. Each of the two fangs is at the front of the mouth on a short maxillary bone that can rotate back and forth. When not in use, the fangs fold back against the roof of the mouth and are enclosed in a membranous sheath. This rotating mechanism allows for very long fangs to be contained in a relatively small mouth. The left and right fangs can be rotated together or independently. During a strike,
3350-437: The head, between the nostrils and the eyes. In fact the pit looks like an extra pair of nostrils. All snakes have the ability to sense warmth with touch and heat receptors like other animals ;however, the highly developed pit of the pit vipers is distinctive. Each pit is made of a pit cavity and an inner cavity, the larger one lies just behind and generally below the level of the nostril, and opens forward. Behind this larger cavity
3417-405: The ideal amount of predigestion for the lowest amount of venom. Almost all vipers have keeled scales , a stocky build with a short tail, and a triangle-shaped head distinct from the neck, owing to the location of the venom glands. The great majority have vertically elliptical, or slit-shaped, pupils that can open wide to cover most of the eye or close almost completely, which helps them to see in
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#17327721304013484-574: The king cobra and kraits ). Elapids may display a series of warning signs if provoked, either obviously or subtly. Cobras and mambas lift their inferior body parts, expand hoods, and hiss if threatened; kraits often curl up before hiding their heads down their bodies. In general, sea snakes are able to respire through their skin. Experiments with the yellow-bellied sea snake, Hydrophis platurus , have shown that this species can satisfy about 20% of its oxygen requirements in this manner, allowing for prolonged dives. The sea kraits ( Laticauda spp. ) are
3551-494: The meantime, Elaps was renamed Homoroselaps and moved back to the Elapidae. However, Nagy et al. (2005) regard it as a sister taxon to Atractaspis , which should have been assigned to the Atractaspididae . * Not including the nominate subspecies With the dangers the taxa presents given their venomous nature it is very difficult for activists and conservationists alike to get species on protection lists such as
3618-545: The modern burrowing blind snakes, which have often been seen as the most primitive group of extant forms. One extant analog of these putative ancestors is the earless monitor Lanthanotus of Borneo (though it is also semiaquatic ). Subterranean species evolved bodies streamlined for burrowing, and eventually lost their limbs. According to this hypothesis, features such as the transparent , fused eyelids ( brille ) and loss of external ears evolved to cope with fossorial difficulties, such as scratched corneas and dirt in
3685-500: The mouth can open nearly 180° and the maxilla rotates forward, erecting the fangs as late as possible so that the fangs do not become damaged, as they are brittle. The jaws close upon impact and the muscular sheaths encapsulating the venom glands contract, injecting the venom as the fangs penetrate the target. This action is very fast; in defensive strikes, it will be more a stab than a bite. Viperids use this mechanism primarily for immobilization and digestion of prey. Pre-digestion occurs as
3752-457: The only cure to treat elapidae bites. There are commercial monovalent and polyvalent antivenoms for cobras, mambas, and some other important elapids. Recently, experimental antivenoms based on recombinant toxins have shown that it is feasible to create antivenoms with a wide spectrum of coverage. The venom of spitting cobras is more cytotoxic rather than neurotoxic. It damages local cells, especially those in eyes, which are deliberately targeted by
3819-575: The other end of the scale, the smallest extant snake is Leptotyphlops carlae , with a length of about 10.4 cm (4.1 in). Most snakes are fairly small animals, approximately 1 m (3.3 ft) in length. Some of the most highly developed sensory systems are found in the Crotalidae, or pit vipers—the rattlesnakes and their associates. Pit vipers have all the sense organs of other snakes, as well as additional aids. Pit refers to special infrared-sensitive receptors located on either side of
3886-515: The other instead of side by side, and most have only one functional lung . Some species retain a pelvic girdle with a pair of vestigial claws on either side of the cloaca . Lizards have independently evolved elongate bodies without limbs or with greatly reduced limbs at least twenty-five times via convergent evolution , leading to many lineages of legless lizards . These resemble snakes, but several common groups of legless lizards have eyelids and external ears, which snakes lack, although this rule
3953-451: The pelvic girdle, appearing as horny projections when visible. Front limbs are nonexistent in all known snakes. This is caused by the evolution of their Hox genes , controlling limb morphogenesis . The axial skeleton of the snakes' common ancestor, like most other tetrapods, had regional specializations consisting of cervical (neck), thoracic (chest), lumbar (lower back), sacral (pelvic), and caudal (tail) vertebrae. Early in snake evolution,
4020-599: The sea snakes least adapted to aquatic life. Their bodies are less compressed laterally, and they have thicker bodies and ventral scaling. Because of this, they are capable of some land movement. They spend much of their time on land, where they lay their eggs and digest prey. Terrestrial elapids are found worldwide in tropical and subtropical regions, mostly in the Southern Hemisphere. Most prefer humid tropical environments, though there are many that can still be found in arid environments. Sea snakes occur mainly in
4087-532: The snakes. The venom may cause intense pain on contact with the eye and may lead to blindness. It is not lethal on skin if no wound provides any chance for the toxins to enter the bloodstream . The table below lists out all of the elapid genera and no subfamilies. In the past, many subfamilies were recognized, or have been suggested for the Elapidae, including the Elapinae, Hydrophiinae (sea snakes), Micrurinae (coral snakes), Acanthophiinae (Australian elapids), and
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#17327721304014154-422: The strike-and-release bite mechanism, which provided a huge benefit to snakes by minimizing contact with potentially dangerous prey animals. This adaptation, then, requires the snake to track down the bitten animal to eat it, in an environment full of other animals of the same species. Western diamondback rattlesnakes respond more actively to mouse carcasses that have been injected with crude rattlesnake venom. When
4221-405: The various components of the venom were separated out, the snakes responded to mice injected with two kinds of disintegrins , which are responsible for allowing the snakes to track down their prey. Type genus = Vipera Laurenti, 1768 Pit vipers have specialized sensory organs near the nostrils called heat-sensing pits. The location of this organ is unique to pit vipers. These pits have
4288-529: The venom contains proteases , which degrade tissues. Secondarily, it is used for self defense, though in cases with nonprey, such as humans, they may give a dry bite (not inject any venom). A dry bite allows the snake to conserve its precious reserve of venom, because once it has been depleted, time is needed to replenish it, leaving the snake vulnerable. In addition to being able to deliver dry bites, vipers can inject larger quantities of venom into larger prey targets, and smaller amounts into small prey. This causes
4355-442: The visual image created by the eyes. Whether family Viperidae is attributed to Oppel (1811), as opposed to Laurenti (1768) or Gray (1825), is subject to some interpretation. The consensus among leading experts, though, is that Laurenti used viperae as the plural of vipera (Latin for "viper", "adder", or "snake") and did not intend for it to indicate a family group taxon. Rather, it is attributed to Oppel, based on his Viperini as
4422-448: The world's most venomous snakes based upon their murine LD 50 values, such as the taipans. Large species, mambas and cobras included, are dangerous for their ability to inject large quantities of venom upon a single envenomation and/or striking at a high position proximal to the victim's brain , which is vulnerable to neurotoxicity. Antivenom is promptly required to be administered if bitten by any elapids. Specific antivenoms are
4489-575: Was the general word for snake. The other term, serpent , is from French, ultimately from Indo-European * serp- 'to creep', which also gave Ancient Greek ἕρπω ( hérpō ) 'I crawl' and Sanskrit sarpá ‘snake’. All modern snakes are grouped within the suborder Serpentes in Linnean taxonomy , part of the order Squamata , though their precise placement within squamates remains controversial. The two infraorders of Serpentes are Alethinophidia and Scolecophidia . This separation
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