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Pit viper
Subfamily of snakes

The Crotalinae, or pit vipers, are a subfamily of vipers found in Asia and the Americas, distinguished by a unique heat-sensing pit organ between the eye and nostril on each side of the head. This organ detects infrared radiation, providing a “sixth sense” that aids in locating warm-blooded prey. The group includes 23 genera such as rattlesnakes, lanceheads, and Asian pit vipers. Sizes range from the small Hypnale hypnale to the large Lachesis muta bushmaster. These vipers also possess specialized muscles that efficiently expel venom from their glands, enhancing their predatory capabilities.

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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.12

Geographic range

The subfamily Crotalinae is found from Central Asia eastward and southward to Japan, China, Indonesia, peninsular India, Nepal, Bangladesh and Sri Lanka. In the Americas, they range from southern Canada southward to Central America to southern South America.13

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.14

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.15

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.16

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.

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.

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.

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. 17

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.

Genera

Genus18Taxon author19Species20Common nameGeographic range21
AgkistrodonPalisot 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.
AtropoidesWerman, 19921Picado's jumping pit viperCosta Rica and western Panama
BothriechisPeters, 185911Palm-pit vipersSouthern Mexico (southeastern Oaxaca and the northern highlands of Chiapas), through Central America to northern South America (Colombia, western Venezuela, Ecuador and northern Peru
BothrocophiasGutberlet & Campbell, 20019Toadheaded pit vipersNorthern South America
BothropsWagler, 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
CalloselasmaCope, 18601Malayan pit viperSoutheast Asia from Thailand to northern Malaysia and Java, Indonesia
CerrophidionCampbell & Lamar, 19925Montane pit vipersSouthern 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
CrotalusTLinnaeus, 175851RattlesnakesThe Americas, from southern Canada to northern Argentina
DeinagkistrodonGloyd, 19791Hundred-pace pit viperSoutheast Asia
GarthiusMalhotra & Thorpe, 20041Mount Kinabalu pit viper, Chasen's mountain pit viperBorneo
GloydiusHoge & 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
HypnaleFitzinger, 18433Hump-nosed pit vipersSri Lanka and India
LachesisDaudin, 18034BushmastersCentral and South America
MetlapilcoatlusCampbell, Frost, & Castoe, 20196Jumping pit vipersThe 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.
MixcoatlusJadin, H.M.Smith & Campbell, 20113Mexican pit vipersMexico
OphryacusCope, 18873Mexican horned pit vipersMexico
OvophisBurger, 19817Mountain pit vipersNepal and Seven Sisters (Assam) of India eastward through Myanmar, Cambodia, Thailand, Laos, Vietnam, West Malaysia, Taiwan, Japan (Okinawa) and Indonesia (Sumatra)
PorthidiumCope, 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)
ProtobothropsHoge & Romano-Hoge, 198314Pit vipersAsia
SistrurusGarman, 18833Ground rattlesnakesSoutheastern Canada, eastern, central and northwestern USA, isolated populations in northern and central Mexico
TrimeresurusLacépède, 180443Asian lanceheadsSoutheast Asia from India to southern China and Japan, and the Malay Archipelago to Timor
TropidolaemusWagler, 18305Temple vipersSouthern India and Southeast Asia

*) Not including the nominate subspecies. T) Type genus.22

See also

Further reading

  • Gumprecht, Andreas; Tillack, Frank (2004). "A proposal for a replacement name of the snake genus Ermia Zhang, 1993". Russian Journal of Herpetology 11: 73–76.
  • Wright, Albert Hazen; Wright, Anna Allen (1957). Handbook of Snakes of the United States and Canada. Ithaca and London: Comstock Publishing Associates, a Division of Cornell University Press. 1,105 pp. (in two volumes). (Seventh Printing 1985). ("Crotalidae", p. 901).
  • Goris RC (2011). "Infrared organs of snakes: an integral part of vision". Journal of Herpetology 45: 2–14.
Wikimedia Commons has media related to Crotalinae. Wikispecies has information related to Crotalinae.

References

  1. Mehrtens JM (1987). Living Snakes of the World in Color. New York: Sterling Publishers. 480 pp. ISBN 0-8069-6460-X. /wiki/ISBN_(identifier) ↩

  2. Sometimes spelled "pitvipers" – Campbell & Lamar, 2004 [page needed] /wiki/Wikipedia:Citing_sources ↩

  3. "Crotalinae". Integrated Taxonomic Information System. Retrieved 26 October 2006. https://www.itis.gov/servlet/SingleRpt/SingleRpt?search_topic=TSN&search_value=634394 ↩

  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. /wiki/ISBN_(identifier) ↩

  5. Mehrtens JM (1987). Living Snakes of the World in Color. New York: Sterling Publishers. 480 pp. ISBN 0-8069-6460-X. /wiki/ISBN_(identifier) ↩

  6. 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. /wiki/ISBN_(identifier) ↩

  7. Mehrtens JM (1987). Living Snakes of the World in Color. New York: Sterling Publishers. 480 pp. ISBN 0-8069-6460-X. /wiki/ISBN_(identifier) ↩

  8. 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). /wiki/ISBN_(identifier) ↩

  9. Bullock, T. H. and Diecke, F. P. J. (1956). Properties of an infrared receptor. Journal of Physiology 134, 47-87. ↩

  10. Stidworthy J. 1974. Snakes of the World. Grosset & Dunlap Inc. 160 pp. ISBN 0-448-11856-4. /wiki/ISBN_(identifier) ↩

  11. 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. /wiki/ISBN_(identifier) ↩

  12. "The first European pit viper from the Miocene of Ukraine - Acta Palaeontologica Polonica". www.app.pan.pl. Retrieved 21 February 2024. https://www.app.pan.pl/article/item/app44-327.html ↩

  13. 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). https://fr.wikipedia.org/wiki/Roy_Wallace_McDiarmid ↩

  14. 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. /wiki/ISBN_(identifier) ↩

  15. 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. https://journals.biologists.com/jeb/article/206/15/2539/20239/Thermoregulation-is-the-pits-use-of-thermal ↩

  16. Shine R, Sun L, Kearney M, Fitzgerald M (2002). "Why do Juvenile Chinese Pit-Vipers (Gloydius shedoaensis) Select Arboreal Ambush Sites?" Ethology 108: 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. /wiki/Richard_Shine ↩

  17. 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. http://www.jstor.org/stable/3891463 ↩

  18. "Crotalinae". Integrated Taxonomic Information System. Retrieved 26 October 2006. https://www.itis.gov/servlet/SingleRpt/SingleRpt?search_topic=TSN&search_value=634394 ↩

  19. "Crotalinae". Integrated Taxonomic Information System. Retrieved 26 October 2006. https://www.itis.gov/servlet/SingleRpt/SingleRpt?search_topic=TSN&search_value=634394 ↩

  20. "Crotalinae". Integrated Taxonomic Information System. Retrieved 26 October 2006. https://www.itis.gov/servlet/SingleRpt/SingleRpt?search_topic=TSN&search_value=634394 ↩

  21. 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). /wiki/ISBN_(identifier) ↩

  22. 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). /wiki/ISBN_(identifier) ↩