Viperidae
Encyclopedia
The Viperidae are a family of venomous snake
s found all over the world, except in Antarctica, Australia
, Ireland
, Madagascar
, Hawaii
, various other isolated islands, and above the Arctic Circle
. All have relatively long, hinged fangs that permit deep penetration and injection of venom
. Four subfamilies are currently recognized. They are commonly known as vipers or viperids.
from glands located towards the rear of the upper jaws. 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. The left and right fangs can be rotated together or independently. During a strike, the mouth can open nearly 180° and the maxilla
rotates forward, erecting the fangs as late as possible so as the fangs do not become damaged. The jaws close on impact and powerful muscles that surround the venom glands contract to inject the venom as the fangs penetrate. This action is very fast; in defensive strikes it can be more a stab than a bite. Viperids use this mechanism primarily for immobilization and digestion of prey. Secondarily it is used for self-defense, though in most cases with non-prey items such as humans they are more likely to give a dry bite
(not inject any venom).
Almost all vipers have keeled scales
, a stocky build with a short tail, and, due to the location of the venom glands, a triangular-shaped head distinct from the neck. The great majority have vertically elliptical, or slit-shaped, pupil
s that can open wide to cover most of the eye or close almost completely, which helps them to see in 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
, giving birth to live young, but a few lay eggs; the word "viper" is derived from Latin vivo = "I live" and pario = "I give birth".
, Africa
and Eurasia
. In the Americas, they are native from southern Canada
south, through the United States
, Mexico
, Central America
and into South America
.The Adder branch of The Viperidae family contains the only venomous snake found in the United Kingdom
. Wild viperids are not found in Australia
.
-degrading enzymes, called protease
s, that produce symptoms such as pain, strong local swelling and necrosis
, blood loss from cardiovascular damage complicated by coagulopathy
, and disruption of the blood clotting system. Death is usually caused by collapse in blood pressure. This is in contrast to elapid venoms that generally contain neurotoxin
s that disable muscle contraction and cause paralysis. Death from elapid bites usually results from asphyxiation because the diaphragm can no longer contract. However, 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 is also dual-purpose: firstly, it is used for defense and to immobilize prey, as with neurotoxic venoms; secondly, many of the venom's enzymes have a digestive function, breaking down molecules in prey items, such as lipid
s, nucleic acid
s, 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, even though it may not necessarily prove fatal. Even with prompt and proper treatment, 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 (but not limited to) 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 and/or the antivenom.
Type genus
= Vipera
—Laurenti, 1768
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 a distinct family group name, despite the fact that Gray was the first to use the form Viperinae.
Venomous snake
"Poisonous snake" redirects here. For true poisonous snakes, see Rhabdophis.Venomous snakes are snakes which have venom glands and specialized teeth for the injection of venom...
s found all over the world, except in Antarctica, Australia
Australia
Australia , officially the Commonwealth of Australia, is a country in the Southern Hemisphere comprising the mainland of the Australian continent, the island of Tasmania, and numerous smaller islands in the Indian and Pacific Oceans. It is the world's sixth-largest country by total area...
, Ireland
Ireland
Ireland is an island to the northwest of continental Europe. It is the third-largest island in Europe and the twentieth-largest island on Earth...
, Madagascar
Madagascar
The Republic of Madagascar is an island country located in the Indian Ocean off the southeastern coast of Africa...
, Hawaii
Hawaii
Hawaii is the newest of the 50 U.S. states , and is the only U.S. state made up entirely of islands. It is the northernmost island group in Polynesia, occupying most of an archipelago in the central Pacific Ocean, southwest of the continental United States, southeast of Japan, and northeast of...
, various other isolated islands, and above the Arctic Circle
Arctic Circle
The Arctic Circle is one of the five major circles of latitude that mark maps of the Earth. For Epoch 2011, it is the parallel of latitude that runs north of the Equator....
. All have relatively long, hinged fangs that permit deep penetration and injection of venom
Venom
Venom is the general term referring to any variety of toxins used by certain types of animals that inject it into their victims by the means of a bite or a sting...
. Four subfamilies are currently recognized. They are commonly known as vipers or viperids.
Description
All viperids have a pair of relatively long solenoglyphous (hollow) fangs that are used to inject venomVenom
Venom is the general term referring to any variety of toxins used by certain types of animals that inject it into their victims by the means of a bite or a sting...
from glands located towards the rear of the upper jaws. Each of the two fangs is at the front of the mouth on a short maxillary
Maxilla
The maxilla is a fusion of two bones along the palatal fissure that form the upper jaw. This is similar to the mandible , which is also a fusion of two halves at the mental symphysis. Sometimes The maxilla (plural: maxillae) is a fusion of two bones along the palatal fissure that form the upper...
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. The left and right fangs can be rotated together or independently. During a strike, the mouth can open nearly 180° and the maxilla
Maxilla
The maxilla is a fusion of two bones along the palatal fissure that form the upper jaw. This is similar to the mandible , which is also a fusion of two halves at the mental symphysis. Sometimes The maxilla (plural: maxillae) is a fusion of two bones along the palatal fissure that form the upper...
rotates forward, erecting the fangs as late as possible so as the fangs do not become damaged. The jaws close on impact and powerful muscles that surround the venom glands contract to inject the venom as the fangs penetrate. This action is very fast; in defensive strikes it can be more a stab than a bite. Viperids use this mechanism primarily for immobilization and digestion of prey. Secondarily it is used for self-defense, though in most cases with non-prey items such as humans they are more likely to give a dry bite
Dry bite
A dry bite is a bite by a venomous animal in which no venom is released. Dry snake bites are called "Venomous snake bite without envenoming". Dry bites can occur from all snakes, but their frequency varies from species to species. For example, brown snakes can inflict dry bites 80% of the time...
(not inject any venom).
Almost all vipers have keeled scales
Keeled scales
Keeled scales refer to reptile scales that, rather than being smooth, have a ridge down the center that may or may not extend to the tip of the scale, making them rough to the touch...
, a stocky build with a short tail, and, due to the location of the venom glands, a triangular-shaped head distinct from the neck. The great majority have vertically elliptical, or slit-shaped, pupil
Pupil
The pupil is a hole located in the center of the iris of the eye that allows light to enter the retina. It appears black because most of the light entering the pupil is absorbed by the tissues inside the eye. In humans the pupil is round, but other species, such as some cats, have slit pupils. In...
s that can open wide to cover most of the eye or close almost completely, which helps them to see in 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
Ovoviviparity
Ovoviviparity, ovovivipary, or ovivipary, is a mode of reproduction in animals in which embryos develop inside eggs that are retained within the mother's body until they are ready to hatch...
, giving birth to live young, but a few lay eggs; the word "viper" is derived from Latin vivo = "I live" and pario = "I give birth".
Geographic range
Viperid snakes are found in the AmericasAmericas
The Americas, or America , are lands in the Western hemisphere, also known as the New World. In English, the plural form the Americas is often used to refer to the landmasses of North America and South America with their associated islands and regions, while the singular form America is primarily...
, Africa
Africa
Africa is the world's second largest and second most populous continent, after Asia. At about 30.2 million km² including adjacent islands, it covers 6% of the Earth's total surface area and 20.4% of the total land area...
and Eurasia
Eurasia
Eurasia is a continent or supercontinent comprising the traditional continents of Europe and Asia ; covering about 52,990,000 km2 or about 10.6% of the Earth's surface located primarily in the eastern and northern hemispheres...
. In the Americas, they are native from southern Canada
Canada
Canada is a North American country consisting of ten provinces and three territories. Located in the northern part of the continent, it extends from the Atlantic Ocean in the east to the Pacific Ocean in the west, and northward into the Arctic Ocean...
south, through the United States
United States
The United States of America is a federal constitutional republic comprising fifty states and a federal district...
, Mexico
Mexico
The United Mexican States , commonly known as Mexico , is a federal constitutional republic in North America. It is bordered on the north by the United States; on the south and west by the Pacific Ocean; on the southeast by Guatemala, Belize, and the Caribbean Sea; and on the east by the Gulf of...
, Central America
Central America
Central America is the central geographic region of the Americas. It is the southernmost, isthmian portion of the North American continent, which connects with South America on the southeast. When considered part of the unified continental model, it is considered a subcontinent...
and into South America
South America
South America is a continent situated in the Western Hemisphere, mostly in the Southern Hemisphere, with a relatively small portion in the Northern Hemisphere. The continent is also considered a subcontinent of the Americas. It is bordered on the west by the Pacific Ocean and on the north and east...
.The Adder branch of The Viperidae family contains the only venomous snake found in the United Kingdom
United Kingdom
The United Kingdom of Great Britain and Northern IrelandIn the United Kingdom and Dependencies, other languages have been officially recognised as legitimate autochthonous languages under the European Charter for Regional or Minority Languages...
. Wild viperids are not found in Australia
Australia
Australia , officially the Commonwealth of Australia, is a country in the Southern Hemisphere comprising the mainland of the Australian continent, the island of Tasmania, and numerous smaller islands in the Indian and Pacific Oceans. It is the world's sixth-largest country by total area...
.
Behavior
Experiments have shown that these snakes are capable of making decisions on how much venom to inject depending on the circumstances. In all cases, the most important determinant of venom expenditure is generally the size of the snake, with larger specimens being capable of delivering much more venom. The species is also important, since some are likely to inject more venom than others, may have much venom available, strike more accurately, or deliver a number of bites in a short space of 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 the assessed level of threat, although larger assailants and higher threat levels may not necessarily lead to larger amounts of venom being injected.Venom
Viperid venoms typically contain an abundance of proteinProtein
Proteins are biochemical compounds consisting of one or more polypeptides typically folded into a globular or fibrous form, facilitating a biological function. A polypeptide is a single linear polymer chain of amino acids bonded together by peptide bonds between the carboxyl and amino groups of...
-degrading enzymes, called protease
Protease
A protease is any enzyme that conducts proteolysis, that is, begins protein catabolism by hydrolysis of the peptide bonds that link amino acids together in the polypeptide chain forming the protein....
s, that produce symptoms such as pain, strong local swelling and necrosis
Necrosis
Necrosis is the premature death of cells in living tissue. Necrosis is caused by factors external to the cell or tissue, such as infection, toxins, or trauma. This is in contrast to apoptosis, which is a naturally occurring cause of cellular death...
, blood loss from cardiovascular damage complicated by coagulopathy
Coagulopathy
Coagulopathy is a condition in which the blood’s ability to clot is impaired. This condition can cause prolonged or excessive bleeding, which may occur spontaneously or following an injury or medical and dental procedures.The normal clotting process depends on the interplay of various proteins in...
, and disruption of the blood clotting system. Death is usually caused by collapse in blood pressure. This is in contrast to elapid venoms that generally contain neurotoxin
Neurotoxin
A neurotoxin is a toxin that acts specifically on nerve cells , usually by interacting with membrane proteins such as ion channels. Some sources are more general, and define the effect of neurotoxins as occurring at nerve tissue...
s that disable muscle contraction and cause paralysis. Death from elapid bites usually results from asphyxiation because the diaphragm can no longer contract. However, 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 is also dual-purpose: firstly, it is used for defense and to immobilize prey, as with neurotoxic venoms; secondly, many of the venom's enzymes have a digestive function, breaking down molecules in prey items, such as lipid
Lipid
Lipids constitute a broad group of naturally occurring molecules that include fats, waxes, sterols, fat-soluble vitamins , monoglycerides, diglycerides, triglycerides, phospholipids, and others...
s, nucleic acid
Nucleic acid
Nucleic acids are biological molecules essential for life, and include DNA and RNA . Together with proteins, nucleic acids make up the most important macromolecules; each is found in abundance in all living things, where they function in encoding, transmitting and expressing genetic information...
s, 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, even though it may not necessarily prove fatal. Even with prompt and proper treatment, a bite can still result in a permanent scar, and in the worst cases, the affected limb may even have to be amputated
Amputation
Amputation is the removal of a body extremity by trauma, prolonged constriction, or surgery. As a surgical measure, it is used to control pain or a disease process in the affected limb, such as malignancy or gangrene. In some cases, it is carried out on individuals as a preventative surgery for...
. A victim's fate is impossible to predict as this depends on many factors, including (but not limited to) 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
Allergy
An Allergy is a hypersensitivity disorder of the immune system. Allergic reactions occur when a person's immune system reacts to normally harmless substances in the environment. A substance that causes a reaction is called an allergen. These reactions are acquired, predictable, and rapid...
to the venom and/or the antivenom.
Subfamilies
| Subfamily | Taxon author | Genera | Species | Common name | Geographic range |
|---|---|---|---|---|---|
| Azemiopinae Azemiopinae Azemiopinae is a monotypic subfamily created for the monotypic genus, Azemiops, that contains the venomous viper species Azemiops feae, described here. No subspecies are recognized. The first specimen was collected by Italian explorer Leonardo Fea, and was described as a new genus and new species... |
Liem, Marx & Rabb, 1971 | 1 | 1 | Fea's viper | Myanmar Myanmar Burma , officially the Republic of the Union of Myanmar , is a country in Southeast Asia. Burma is bordered by China on the northeast, Laos on the east, Thailand on the southeast, Bangladesh on the west, India on the northwest, the Bay of Bengal to the southwest, and the Andaman Sea on the south.... , southeastern Tibet Tibet Tibet is a plateau region in Asia, north-east of the Himalayas. It is the traditional homeland of the Tibetan people as well as some other ethnic groups such as Monpas, Qiang, and Lhobas, and is now also inhabited by considerable numbers of Han and Hui people... across southern China China Chinese civilization may refer to:* China for more general discussion of the country.* Chinese culture* Greater China, the transnational community of ethnic Chinese.* History of China* Sinosphere, the area historically affected by Chinese culture... (Fujien, Guangxi Guangxi Guangxi, formerly romanized Kwangsi, is a province of southern China along its border with Vietnam. In 1958, it became the Guangxi Zhuang Autonomous Region of the People's Republic of China, a region with special privileges created specifically for the Zhuang people.Guangxi's location, in... , Jiangxi Jiangxi ' is a southern province in the People's Republic of China. Spanning from the banks of the Yangtze River in the north into hillier areas in the south, it shares a border with Anhui to the north, Zhejiang to the northeast, Fujian to the east, Guangdong to the south, Hunan to the west, and Hubei to... , Kweichow, Sichuan Sichuan ' , known formerly in the West by its postal map spellings of Szechwan or Szechuan is a province in Southwest China with its capital in Chengdu... , Yunnan Yunnan Yunnan is a province of the People's Republic of China, located in the far southwest of the country spanning approximately and with a population of 45.7 million . The capital of the province is Kunming. The province borders Burma, Laos, and Vietnam.Yunnan is situated in a mountainous area, with... , Zhejiang Zhejiang Zhejiang is an eastern coastal province of the People's Republic of China. The word Zhejiang was the old name of the Qiantang River, which passes through Hangzhou, the provincial capital... ) to northern Vietnam Vietnam Vietnam – sometimes spelled Viet Nam , officially the Socialist Republic of Vietnam – is the easternmost country on the Indochina Peninsula in Southeast Asia. It is bordered by China to the north, Laos to the northwest, Cambodia to the southwest, and the South China Sea –... . |
| Causinae Causinae The Causinae are a monotypic subfamily of venomous vipers found only in subsaharan Africa. It was created for the genus Causus; a group considered to be among the most primitive members of the family Viperidae based on head scalation, oviparity, venom apparatus and the fact that they have round... |
Cope Edward Drinker Cope Edward Drinker Cope was an American paleontologist and comparative anatomist, as well as a noted herpetologist and ichthyologist. Born to a wealthy Quaker family, Cope distinguished himself as a child prodigy interested in science; he published his first scientific paper at the age of nineteen... , 1859 |
1 | 6 | Night adders | Subsaharan Africa Sub-Saharan Africa Sub-Saharan Africa as a geographical term refers to the area of the African continent which lies south of the Sahara. A political definition of Sub-Saharan Africa, instead, covers all African countries which are fully or partially located south of the Sahara... |
| Crotalinae Crotalinae The Crotalinae, commonly known as "pit vipers" or crotaline snakes, are a subfamily of venomous vipers found in Asia and the Americas. They are distinguished by the presence of a heat-sensing pit organ located between the eye and the nostril on either side of the head... |
Oppel Nicolaus Michael Oppel Nicolaus Michael Oppel was a German naturalist. He was a student of, and worked as an assistant to, André Marie Constant Duméril at the Muséum national d'histoire naturelle in Paris, France, cataloging and classifying species of reptiles... , 1811 |
18 | 151 | Pit vipers | In the Old World Old World The Old World consists of those parts of the world known to classical antiquity and the European Middle Ages. It is used in the context of, and contrast with, the "New World" .... from eastern Europe Europe Europe is, by convention, one of the world's seven continents. Comprising the westernmost peninsula of Eurasia, Europe is generally 'divided' from Asia to its east by the watershed divides of the Ural and Caucasus Mountains, the Ural River, the Caspian and Black Seas, and the waterways connecting... eastward through Asia Asia Asia is the world's largest and most populous continent, located primarily in the eastern and northern hemispheres. It covers 8.7% of the Earth's total surface area and with approximately 3.879 billion people, it hosts 60% of the world's current human population... to Japan Japan Japan is an island nation in East Asia. Located in the Pacific Ocean, it lies to the east of the Sea of Japan, China, North Korea, South Korea and Russia, stretching from the Sea of Okhotsk in the north to the East China Sea and Taiwan in the south... , Taiwan Taiwan Taiwan , also known, especially in the past, as Formosa , is the largest island of the same-named island group of East Asia in the western Pacific Ocean and located off the southeastern coast of mainland China. The island forms over 99% of the current territory of the Republic of China following... , Indonesia Indonesia Indonesia , officially the Republic of Indonesia , is a country in Southeast Asia and Oceania. Indonesia is an archipelago comprising approximately 13,000 islands. It has 33 provinces with over 238 million people, and is the world's fourth most populous country. Indonesia is a republic, with an... , peninsular India India India , officially the Republic of India , is a country in South Asia. It is the seventh-largest country by geographical area, the second-most populous country with over 1.2 billion people, and the most populous democracy in the world... and Sri Lanka Sri Lanka Sri Lanka, officially the Democratic Socialist Republic of Sri Lanka is a country off the southern coast of the Indian subcontinent. Known until 1972 as Ceylon , Sri Lanka is an island surrounded by the Indian Ocean, the Gulf of Mannar and the Palk Strait, and lies in the vicinity of India and the... . In the New World New World The New World is one of the names used for the Western Hemisphere, specifically America and sometimes Oceania . The term originated in the late 15th century, when America had been recently discovered by European explorers, expanding the geographical horizon of the people of the European middle... from southern Canada Canada Canada is a North American country consisting of ten provinces and three territories. Located in the northern part of the continent, it extends from the Atlantic Ocean in the east to the Pacific Ocean in the west, and northward into the Arctic Ocean... southward through Mexico Mexico The United Mexican States , commonly known as Mexico , is a federal constitutional republic in North America. It is bordered on the north by the United States; on the south and west by the Pacific Ocean; on the southeast by Guatemala, Belize, and the Caribbean Sea; and on the east by the Gulf of... and Central America Central America Central America is the central geographic region of the Americas. It is the southernmost, isthmian portion of the North American continent, which connects with South America on the southeast. When considered part of the unified continental model, it is considered a subcontinent... to southern South America South America South America is a continent situated in the Western Hemisphere, mostly in the Southern Hemisphere, with a relatively small portion in the Northern Hemisphere. The continent is also considered a subcontinent of the Americas. It is bordered on the west by the Pacific Ocean and on the north and east... . |
| Viperinae Viperinae The Viperinae, or viperines, are a subfamily of venomous vipers found in Europe, Asia and Africa. They are distinguished by their lack of the heat-sensing pit organs that characterize their sister group, the Crotalinae. Currently, 12 genera and 66 species are recognized... |
Oppel Nicolaus Michael Oppel Nicolaus Michael Oppel was a German naturalist. He was a student of, and worked as an assistant to, André Marie Constant Duméril at the Muséum national d'histoire naturelle in Paris, France, cataloging and classifying species of reptiles... , 1811 |
12 | 66 | True or pitless vipers | Europe, Asia and Africa Africa Africa is the world's second largest and second most populous continent, after Asia. At about 30.2 million km² including adjacent islands, it covers 6% of the Earth's total surface area and 20.4% of the total land area... . |
Type genus
Type genus
In biological classification, a type genus is a representative genus, as with regard to a biological family. The term and concept is used much more often and much more formally in zoology than it is in botany, and the definition is dependent on the nomenclatural Code that applies:* In zoological...
= Vipera
Vipera
Vipera is a genus of venomous vipers. It has a very wide range, being found from North Africa to just within the Arctic Circle and from Great Britain to Pacific Asia. The name is possibly derived from the Latin words vivus and pario, meaning "alive" and "bear" or "bring forth"; likely a reference...
—Laurenti, 1768
Taxonomy
That Viperidae as attributed to Oppel (1811), as opposed to Laurenti (1768) or Gray (1825), is subject to some interpretation. However, the consensus among leading experts is that Laurenti used viperae as the pluralPlural
In linguistics, plurality or [a] plural is a concept of quantity representing a value of more-than-one. Typically applied to nouns, a plural word or marker is used to distinguish a value other than the default quantity of a noun, which is typically one...
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 a distinct family group name, despite the fact that Gray was the first to use the form Viperinae.