Pit viper

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Pit viper
Temporal range: Early Miocene–present
Timber Rattlesnake by Trisha.jpg
Timber rattlesnake (Crotalus horridus), showing the characteristic infrared pit below and between the eye and nostril
Scientific classification OOjs UI icon edit-ltr.svg
Domain: Eukaryota
Kingdom: Animalia
Phylum: Chordata
Class: Reptilia
Order: Squamata
Suborder: Serpentes
Family: Viperidae
Subfamily: Crotalinae
Oppel, 1811
Synonyms
  • Crotalini Oppel, 1811
  • Crotales Cuvier, 1817
  • Crotalidae Gay, 1825
  • Crotaloidae Fitzinger, 1826
  • Cophiadae Boie, 1827
  • Crotaloidei Eichwald, 1831
  • Crotalina Bonaparte, 1831
  • Bothrophes Fitzinger, 1843
  • Crotalinae Cope, 1860
  • Teleuraspides Cope, 1871
  • Crotalida Strauch, 1873
  • Bothrophera Garman, 1884
  • Cophiinae Cope, 1895
  • Lachesinae Cope, 1900
  • Lachesinii Smith, Smith & Sawin, 1977
  • Agkistrodontinii Hoge & Romano-Hoge, 1981
  • Agkistrodontini Hoge & Romano-Hoge, 1983 [1]

The Crotalinae, commonly known as pit vipers, [2] [3] or pit adders, are a subfamily of vipers found in Asia and the Americas. Like all other vipers, they are venomous. They are distinguished by the presence of a heat-sensing pit organ located between the eye and the nostril on both sides of the head. Currently, 23 genera and 155 species are recognized: [4] These are also the only viperids found in the Americas. The groups of snakes represented here include rattlesnakes, lanceheads, and Asian pit vipers. The type genus for this subfamily is Crotalus , of which the type species is the timber rattlesnake, C. horridus.[ citation needed ]

Contents

These snakes range in size from the diminutive hump-nosed viper, Hypnale hypnale , that grows to a typical total length (including tail) of only 30–45 cm (12–18 in), to the bushmaster, Lachesis muta , a species known to reach a maximum total length of 3.65 m (12.0 ft) in length.

This subfamily is unique in that all member species share a common characteristic – a deep pit, or fossa, in the loreal area between the eye and the nostril on either side of the head. These loreal pits are the external openings to a pair of extremely sensitive infrared-detecting organs, which in effect give the snakes a sixth sense to help them find and perhaps even judge the size of the small, warm-blooded prey on which they feed. [5] The pit organ is complex in structure and is similar to the thermoreceptive labial pits found in boas and pythons. It is deep and located in a maxillary cavity. The membrane is like an eardrum that divides the pit into two sections of unequal size, with the larger of the two facing forwards and exposed to the environment. The two sections are connected via a narrow tube, or duct, that can be opened or closed by a group of surrounding muscles. By controlling this tube, the snake can balance the air pressure on either side of the membrane. [2] The membrane has many nerve endings packed with mitochondria. Succinic dehydrogenase, lactic dehydrogenase, adenosine triphosphate, monoamine oxidase, generalized esterases, and acetylcholine esterase have also been found in it. [5] When prey comes into range, infrared radiation falling onto the membrane allows the snake to determine its direction. [2] Having one of these organs on either side of the head produces a stereo effect that indicates distance, as well as direction. Experiments have shown, when deprived of their senses of sight and smell, these snakes can strike accurately at moving objects less than 0.2 °C (0.36 °F) warmer than the background. [6] The paired pit organs provide the snake with thermal rangefinder capabilities. [7] Clearly, these organs are of great value to a predator that hunts at night, as well as for avoiding the snake’s own predators. [8]

Among vipers, these snakes are also unique in that they have a specialized muscle, called the muscularis pterigoidius glandulae, between the venom gland and the head of the ectopterygoid. Contraction of this muscle, together with that of the muscularis compressor glandulae, forces venom out of the gland. [5]

Evolution

The earliest known fossil pit viper remains are from the Early Miocene of Nebraska. As pit vipers are thought to have had an Asian origin before eventually colonizing the Americas, this suggests that they must have originated and diversified even earlier. During the Late Miocene, they reached as far west as eastern Europe, where they are no longer found; it is thought that they did not expand further into Europe. [9]

Geographic range

The subfamily Crotalinae is found from Central Asia eastward and southward to Japan, China, Indonesia, peninsular India, Nepal, and Sri Lanka. In the Americas, they range from southern Canada southward to Central America to southern South America. [1]

Habitat

Crotalines are a versatile subfamily, with members found in habitats ranging from parched desert (e.g., the sidewinder, Crotalus cerastes ) to rainforests (e.g., the bushmaster, Lachesis muta). They may be either arboreal or terrestrial, and at least one species (the cottonmouth, Agkistrodon piscivorus ) is semiaquatic. The altitude record is held jointly by Crotalus triseriatus in Mexico and Gloydius strauchi in China, both of which have been found above the treeline at over 4,000 m above sea level. [5]

Behavior

Although a few species of crotalines are highly active by day, such as Trimeresurus trigonocephalus , a bright green pit viper endemic to Sri Lanka, most are nocturnal, preferring to avoid high daytime temperatures and to hunt when their favored prey are also active. The snakes' heat-sensitive pits are also thought to aid in locating cooler areas in which to rest. [10]

As ambush predators, crotalines typically wait patiently somewhere for unsuspecting prey to wander by. At least one species, the arboreal Gloydius shedaoensis of China, is known to select a specific ambush site and return to it every year in time for the spring migration of birds. Studies have indicated these snakes learn to improve their strike accuracy over time. [11]

Many temperate species of pit vipers (e.g. most rattlesnakes) congregate in sheltered areas or "dens" to overwinter (brumate, see hibernation), the snakes benefiting from the combined heat. In cool temperatures and while pregnant, pit vipers also bask on sunny ledges. Some species do not mass together in this way, for example the copperhead, Agkistrodon contortrix , or the Mojave rattlesnake, Crotalus scutulatus .[ citation needed ]

Like most snakes, crotalines keep to themselves and strike only if cornered or threatened. Smaller snakes are less likely to stand their ground than larger specimens. Pollution and the destruction of rainforests have caused many pit viper populations to decline. Humans also threaten pit vipers, as many are hunted for their skins or killed by cars when they wander onto roads.[ citation needed ]

Reproduction

With few exceptions, crotalines are ovoviviparous, meaning that the embryos develop within eggs that remain inside the mother's body until the offspring are ready to hatch, when the hatchlings emerge as functionally free-living young. In such species, the eggshells are reduced to soft membranes that the young shed, either within the reproductive tract, or immediately after emerging.

Among the oviparous (egg-laying) pit vipers are Lachesis , Calloselasma , and some Trimeresurus species. All egg-laying crotalines are believed to guard their eggs.[ citation needed ]

Brood sizes range from two for very small species, to as many as 86 for the fer-de-lance, Bothrops atrox , which is among the most prolific of all live-bearing snakes.

Many young crotalines have brightly coloured tails that contrast dramatically with the rest of their bodies. These tails are known to be used by a number of species in a behavior known as caudal luring; the young snakes make worm-like movements with their tails to lure unsuspecting prey within striking distance. [12]

Taxonomy

In the past, the pit vipers were usually classed as a separate family: the Crotalidae. Today, however, the monophyly of the viperines and the crotalines as a whole is undisputed, which is why they are treated here as a subfamily of the Viperidae.[ citation needed ]

Genera

Genus [ref 1] Taxon author [ref 1] Species [ref 1] Common nameGeographic range [ref 2]
Agkistrodon Palisot de Beauvois, 17996MoccasinsNorth America from the northeastern and central USA southward through peninsular Florida and southwestern Texas. In Central America on the Atlantic versant from Tamaulipas and Nuevo León southward to the Yucatán Peninsula, Belize and Guatemala. Along the Pacific coastal plain and lower foothills from Sonora south through Guatemala, El Salvador, Honduras and Nicaragua to northwestern Costa Rica.
Atropoides Werman, 19921Picado's jumping pitviperCosta Rica and western Panama
Bothriechis Peters, 185911Palm-pitvipersSouthern Mexico (southeastern Oaxaca and the northern highlands of Chiapas), through Central America to northern South America (Colombia, western Venezuela, Ecuador and northern Peru
Bothrocophias Gutberlet & Campbell, 20019Toadheaded pit vipersNorthern South America
Bothrops Wagler, 182448LanceheadsNortheastern Mexico (Tamaulipas) southward through Central and South America to Argentina; Saint Lucia and Martinique in the Lesser Antilles; Ilha da Queimada Grande off the coast of Brazil
Calloselasma Cope, 18601Malayan pitviperSoutheast Asia from Thailand to northern Malaysia and Java, Indonesia
Cerrophidion Campbell & Lamar, 19925Montane pitvipersSouthern Mexico (highlands of Guerrero and southeastern Oaxaca), southward through the highlands of Central America (Guatemala, El Salvador, Honduras, northern Nicaragua, Costa Rica) to western Panama
Craspedocephalus Kuhl & van Hasselt, 182215Pit viperIndia to Thailand to northern Malaysia and Indonesia
Crotalus T Linnaeus, 1758 51RattlesnakesThe Americas, from southern Canada to northern Argentina
Deinagkistrodon Gloyd, 19791Hundred-pace pitviperSoutheast Asia
Garthius Malhotra & Thorpe, 20041Mount Kinabalu pit viper, Chasen's mountain pit viper Borneo
Gloydius Hoge & Romano-Hoge, 198122Asian moccasinsRussia, east of the Ural Mountains through Siberia, Iran, the Himalayas from Pakistan, India, Nepal and China, Korea, Japan and the Ryukyu Islands
Hypnale Fitzinger, 18433Hump-nosed pit vipers Sri Lanka and India
Lachesis Daudin, 18034BushmastersCentral and South America
Metlapilcoatlus Campbell, Frost, & Castoe, 20196Jumping pitvipersThe mountains of eastern Mexico southeastward on the Atlantic versant and lowlands though Central America to central Panama. On the Pacific versant, they occur in isolated populations in east-central and southern Mexico, Guatemala, El Salvador, Costa Rica, and Panama.
Mixcoatlus Jadin, H.M.Smith & Campbell, 20113Mexican pit vipersMexico
Ophryacus Cope, 18873Mexican horned pitvipersMexico
Ovophis Burger, 19817Mountain pit vipersNepal and Seven Sisters (Assam) of India eastward through Myanmar, Cambodia, Thailand, Laos, Vietnam, West Malaysia, Taiwan, Japan (Okinawa) and Indonesia (Sumatra)
Porthidium Cope, 18719Hognose pit vipersMexico (Colima, Oaxaca and Chiapas on the Pacific side, the Yucatán Peninsula on the Atlantic side) southward through Central America to northern South America (Ecuador in the Pacific lowlands, northern Venezuela in the Atlantic lowlands)
Protobothrops Hoge & Romano-Hoge, 198314Pit vipersAsia
Sistrurus Garman, 18833Ground rattlesnakesSoutheastern Canada, eastern, central and northwestern USA, isolated populations in northern and central Mexico
Trimeresurus Lacépède, 180443Asian lanceheadsSoutheast Asia from India to southern China and Japan, and the Malay Archipelago to Timor
Tropidolaemus Wagler, 18305Temple vipersSouthern India and Southeast Asia

*) Not including the nominate subspecies.[ citation needed ]
T) Type genus. [ref 2]

  1. 1 2 3 "Crotalinae". Integrated Taxonomic Information System . Retrieved 26 October 2006.
  2. 1 2 McDiarmid RW, Campbell JA, Touré T. 1999. Snake Species of the World: A Taxonomic and Geographic Reference, vol. 1. Herpetologists' League. 511 pp. ISBN   1-893777-00-6 (series). ISBN   1-893777-01-4 (volume).

See also

Related Research Articles

<span class="mw-page-title-main">Viperinae</span> Subfamily of snakes

Viperinae, or viperines, are a subfamily of vipers endemic to Europe, Asia and Africa. They are distinguished by their lack of the heat-sensing pit organs that characterize their sister group, the subfamily Crotalinae. Currently, 13 genera are recognized. Most are tropical and subtropical, although one species, Vipera berus, even occurs within the Arctic Circle. Like all vipers, they are venomous.

<i>Lachesis</i> (genus) Genus of snakes

Lachesis is a genus of venomous pit vipers in the family Viperidae. Member species are found in forested areas of the Neotropics. The generic name refers to one of the Three Fates, Lachesis, who determined the length of the thread of life. Four species are currently recognized as being valid.

<span class="mw-page-title-main">Rattlesnake</span> Group of venomous snakes of the genera Crotalus and Sistrurus

Rattlesnakes are venomous snakes that form the genera Crotalus and Sistrurus of the subfamily Crotalinae. All rattlesnakes are vipers. Rattlesnakes are predators that live in a wide array of habitats, hunting small animals such as birds and rodents.

<span class="mw-page-title-main">Viperidae</span> Family of snakes

The Viperidae (vipers) are a family of snakes 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, 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" 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 like most of the species of Boidae.

<i>Sistrurus</i> Genus of snakes

Sistrurus is a genus of venomous pit vipers in the subfamily Crotalinae of the family Viperidae. The genus is endemic to Canada, the United States, and Mexico. Its generic name is a 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. Three species are currently recognized.

<i>Craspedocephalus strigatus</i> Species of reptile

Craspedocephalus strigatus, commonly known as the horseshoe pit viper, is a species of venomous snake in the subfamily Crotalinae of the family Viperidae. The species is endemic to the Western Ghats of India. There are no subspecies that are recognized as being valid.

<i>Hypnale</i> Genus of snakes

Hypnale is a genus of venomous pit vipers endemic to Sri Lanka and southwestern India. Three monotypic species are currently recognized. All members have more or less upturned snouts that produce a hump-nosed effect.

<i>Trimeresurus albolabris</i> Species of snake

Trimeresurus albolabris, the white-lipped pit viper or white-lipped tree viper, is a venomous pit viper species endemic to Southeast Asia.

Trimeresurus cantori, commonly known as Cantor's pit viper or Cantor's pitviper, is a species of venomous snake, a pit viper in the Subfamily Crotalinae of the family Viperidae. The species is endemic to the Nicobar Islands of India. It was named after Theodore Edward Cantor (1809-1860), a Danish naturalist serving as a surgeon with the East India Company in Calcutta. No subspecies are recognized as being valid.

Crotalidae polyvalent immune Fab (ovine), sold under the brandname CroFab, is a snake antivenin, indicated for North American crotalid (rattlesnake, copperhead and cottonmouth/water moccasin) snake envenomation.

<i>Tropidolaemus</i> Genus of snakes

Tropidolaemus is a genus of venomous pit vipers found in southern India and Southeast Asia. Currently, 5 species are recognised and no subspecies.

<i>Crotalus basiliscus</i> Species of reptile

Crotalus basiliscus, known as the Mexican west coast rattlesnake, Mexican green rattler, and also by other names, is a species of pit viper in the family Viperidae. The species is endemic to western Mexico. Like all other pit vipers, it is venomous. The specific name, basiliscus, is derived from the Greek word for king, βασιλισκος, and alludes to this snake's large size and potent venom. No subspecies are currently recognized.

<i>Crotalus helleri</i> Species of snake

Crotalus helleri or Crotalus oreganus helleri, also known commonly as the Southern Pacific rattlesnake, the black diamond rattlesnake, and by several other common names, is a pit viper species or subspecies found in southwestern California and south into Baja California, Mexico, that is known for its regional variety of dangerous venom types. It is sometimes considered a subspecies of Crotalus oreganus.

<i>Hypnale hypnale</i> Species of snake

Hypnale hypnale is a venomous pit viper species endemic to India and Sri Lanka. Common names include the hump-nosed viper, Merrem's hump-nosed viper and others listed below at § Common names.

<i>Protobothrops mangshanensis</i> Species of snake

Protobothrops mangshanensis, commonly known as the Mangshan pit viper, Mangshan pitviper, Mt. Mang pitviper, or Mang Mountain pitviper, is a venomous pit viper species endemic to Hunan and Guangdong provinces in China. No subspecies are currently recognized. This is a nocturnal pit viper that is also known as the ''Mangshan iron-head snake'', ''Chinese pit viper'', and the ''Ironhead viper''. They eat frogs, birds, insects, and small mammals. They have a white tail tip that they wiggle to mimic a grub so that prey comes into striking range—a behaviour known as caudal luring. The venom causes blood clotting and corrodes muscle tissue and can be fatal to humans if not treated. Unusually for vipers, P. mangshanensis is oviparous with the female laying clutches of 13–21 eggs which she will guard until they hatch.

<i>Crotalus stejnegeri</i> Species of snake

Crotalus stejnegeri, commonly known as the Sinaloan long-tailed rattlesnake or just long-tailed rattlesnake, is a venomous pit viper species in the family Viperidae. The species is native to western Mexico. There are no recognized subspecies.

<i>Crotalus concolor</i> Species of snake

Crotalus concolor, commonly known as the midget faded rattlesnake, faded rattlesnake, and yellow rattlesnake, is a pit viper species found in the western United States. It is a small rattlesnake known for its faded color pattern. Like all other pit vipers, it is venomous.

<span class="mw-page-title-main">Infrared sensing in snakes</span>

The ability to sense infrared thermal radiation evolved independently in two different groups of snakes, one consisting of the families Boidae (boas) and Pythonidae (pythons), the other of the family Crotalinae. What is commonly called a pit organ allows these animals to essentially "see" radiant heat at wavelengths between 5 and 30 μm. The more advanced infrared sense of pit vipers allows these animals to strike prey accurately even in the absence of light, and detect warm objects from several meters away. It was previously thought that the organs evolved primarily as prey detectors, but recent evidence suggests that it may also be used in thermoregulation and predator detection, making it a more general-purpose sensory organ than was supposed.

Gloydius strauchi is a species of venomous pit viper in the subfamily Crotalinae of the family Viperidae. The species is native to western China. It is a small snake with a pattern of four longitudinal stripes, although some older specimens may be a uniform black. G. strauchi may be distinguished from G. monticola by its higher midbody dorsal scale count. This species jointly holds the altitude record for pitvipers together with Crotalus triseriatus of Mexico, both being found even above the tree line at over 4,000 m (13,000 ft). No subspecies were recognized as being valid, until a recent publication re-evaluated the taxonomic statuses of populations of G. strauchi and described the eastern Tibetan populations as a new species.

References

  1. 1 2 McDiarmid RW, Campbell JA, Touré T (1999). Snake Species of the World: A Taxonomic and Geographic Reference, Volume 1. Washington, District of Columbia: Herpetologists' League. 511 pp. ISBN   1-893777-00-6 (series). ISBN   1-893777-01-4 (volume).
  2. 1 2 3 Mehrtens JM (1987). Living Snakes of the World in Color. New York: Sterling Publishers. 480 pp. ISBN   0-8069-6460-X.
  3. Sometimes spelled "pitvipers" – Campbell & Lamar, 2004 [ page needed ]
  4. "Crotalinae". Integrated Taxonomic Information System . Retrieved 26 October 2006.
  5. 1 2 3 4 Campbell JA, Lamar WW (2004). The Venomous Reptiles of the Western Hemisphere. Ithaca and London: Comstock Publishing Associates. 870 pp., 1,500 plates. ISBN   0-8014-4141-2.
  6. Parker HW, Grandison AGC. 1977. Snakes -- a natural history. Second Edition. British Museum (Natural History) and Cornell University Press. 108 pp. 16 plates. LCCCN 76-54625. ISBN   0-8014-1095-9 (cloth), ISBN   0-8014-9164-9 (paper).
  7. Bullock, T. H. and Diecke, F. P. J. (1956). Properties of an infrared receptor. Journal of Physiology 134, 47-87.
  8. Stidworthy J. 1974. Snakes of the World. Grosset & Dunlap Inc. 160 pp. ISBN   0-448-11856-4.
  9. "The first European pit viper from the Miocene of Ukraine - Acta Palaeontologica Polonica". www.app.pan.pl. Retrieved 21 February 2024.
  10. Krochmal, Aaron R.; Bakken, George S. (1 August 2003). "Thermoregulation is the pits: use of thermal radiation for retreat site selection by rattlesnakes". Journal of Experimental Biology. 206 (15): 2539–2545. doi:10.1242/jeb.00471. PMID   12819261. S2CID   18140029 . Retrieved 11 June 2022.
  11. Shine R, Sun L, Kearney M, Fitzgerald M (2002). "Why do Juvenile Chinese Pit-Vipers (Gloydius shedoaensis) Select Arboreal Ambush Sites?" Ethology108: 897–910. ISSN 0179-1613. PDF Archived 24 July 2008 at the Wayback Machine at University of Sydney School of Biological Sciences. Accessed 26 October 2006.
  12. Heatwole, H.; Davison, Elizabeth (1976). "A Review of Caudal Luring in Snakes with Notes on Its Occurrence in the Saharan Sand Viper, Cerastes vipera". Herpetologica. 32 (3): 332–336. JSTOR   3891463 . Retrieved 24 August 2021.

Further reading