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Agkistrodon contortrix contortrix

Agkistrodon contortrix contortrix

Superregnum: Eukaryota
Regnum: Animalia
Subregnum: Eumetazoa
Cladus: Bilateria
Cladus: Nephrozoa
Superphylum: Deuterostomia
Phylum: Chordata
Subphylum: Vertebrata
Infraphylum: Gnathostomata
Superclassis: Tetrapoda
Cladus: Reptiliomorpha
Cladus: Amniota
Classis: Reptilia
Cladus: Eureptilia
Cladus: Romeriida
Subclassis: Diapsida
Cladus: Sauria
Infraclassis: Lepidosauromorpha
Superordo: Lepidosauria
Ordo: Squamata
Subordo: Serpentes
Infraordo: Caenophidia
Superfamilia: Viperoidea

Familia: Viperidae
Subfamilia: Crotalinae
Genus: Agkistrodon
Species: Agkistrodon contortrix

Agkistrodon contortrix


Agkistrodon contortrix (Linnaeus, 1766)

Type material: not designated, unknown.
Type locality: “Carolina”, restricted to “Charleston, South Carolina” by Schmidt (1953: 224).


Boa contortrix Linnaeus, 1766: 373 [original combination]
Scytale contortrix — Latreille, 1802: 159 [subsequent combination]
Trigonocephalus contortrix — Holbrook, 1838: 69 [subsequent combination]
Cenchris contortrix — Gray, 1842: 50 [subsequent combination]
Agkistrodon contortrix — Baird & Girard, 1853: 17 [subsequent combination]
Ancistrodon contortrix — Baird, 1854: 13 [subsequent combination]


Agkistrodon mokasen Palisot de Beauvois, 1799: 370
Type material: unknown.
Type locality: not stated.

Cenchris mokason Daudin, 1803: 358
Type material: unknown.
Type locality: “Philadelphia”, restricted to “vicinity of Philadelphia, Pennsylvania”.

Scytalus cupreus Rafinesque, 1818: 85
Type material: unknown.
Neotype: UMMZ 81758.
Type locality: not stated, designated by neotype designation to “2 miles south of Fishkill, Dutchess County, New York”.

Cenchris marmorata Boie, 1827: 562
Type material: unknown.
Type locality: not stated.

Acontias atro-fuscus Troost, 1836: 181
Holotype: unknown.
Type locality: “Maury county, Tenn. [=Tennessee]”.

Trigonocephalus cenchris Schlegel, 1837: 553
Type material: unknown.
Type locality: “habite les provinces méridionales des États-Unis de l'Amérique du Nord”.

Trigonocephalus histrionicus Duméril, 1853: 534
Type material: unknown.
Type locality: not stated.

Agkistrodon mokason austrinus Goyd & Conant, 1945: 153
Holotype: CHAS 5089, adult ♀, collected by Percy Viosca Jr. in 1933.
Type locality: “Gentilly, Orleans Parish, Louisiana”.

Agkistrodon contortrix phaeogaster Gloyd, 1969: 220
Holotype: USNM 165955, adult ♂, received from Henry S. Fitch in July 1960.
Type locality: “10 miles south of McLouth, Jefferson County, Kansas”.

Primary references

Linnaeus, C. 1766. Systema naturae sive regna tria naturae, secundum classes, ordines, genera, species, cum characteribus, differentiis, synonymis, locis. Laurentii Salvii: Holmiae. 12th ed. v. 1 (pt 1): 1–532. BHL Reference page.
Palisot de Beauvois, M. 1799. Memoir on Amphibia. Serpents. Transactions of the American Philosophical Society 4: 362–381. BHL Reference page.
Daudin, F.M. 1803. Histoire naturelle, générale et particulière, des reptiles : ouvrage faisant suite à l'Histoire naturelle générale et particulière, composée par Leclerc de Buffon, et rédigée par C.S. Sonnini. Tome Cinquième. L'Imprimerie de F. Dufart: Paris. 365 pp. + plates LIX–LXX. BHL Reference page.
Rafinesque, C.S. 1818. Natural History of the Scytalus Cupreus, or Copper-head Snake. American Journal of Science 1: 84–86. BHL Reference page.
Boie, F. 1827. Bemerkungen über Merrem’s Versuch eines Systems der Amphibien. Marburg, 1820. 1te Lieferung, Ophidier. Isis von Oken 20(6): 508–566. BHL Reference page.
Troost, G. 1836. On a new genus of serpents, and two new species of the genus Heterodon, inhabiting Tennessee. Annals of the Lyceum of Natural History of New York 3: 174–190. BHL Reference page.
Schlegel, H. 1837. Essai sur la physionomie des serpens. Partie Descriptive. Volume 2. M.H. Schonekat: Amsterdam, The Netherlands. 606 pp. BHL Reference page.
Duméril, A.M.C. 1853. Prodrome de la classification des reptiles ophidiens. Mémoires de l'Académie de Sciences de l'Institut de France 23: 399–536. BHL Reference page.
Gloyd, H.K. & Conant, R. 1943. A synopsis of the American forms of Agkistrodon (copperheads and moccasins). Bulletin of the Chicago Academy of Sciences 7(2): 147–170. Reference page.
Gloyd, H.K. 1969. Two additional subspecies of North American crotalid snakes, genus Agkistrodon. Proceedings of the Biological Society of Washington 82(1): 219–232. BHL Reference page.

Additional references

Burbrink, F.T. & Guiher, T.J. 2015. Considering gene flow when using coalescent methods to delimit lineages of North American pitvipers of the genus Agkistrodon. Zoological Journal of the Linnean Society 173(2): 505–526. DOI: 10.1111/zoj.12211 Open access Reference page.


Uetz, P. & Hallermann, J. 2022. Agkistrodon contortrix. The Reptile Database. Accessed on 21 May 2021.
Frost, D.R., Hammerson, G.A. & Santos-Barrera, G. 2007. IUCN: Agkistrodon contortrix (Least Concern). The IUCN Red List of Threatened Species 2007: e.T64297A12756101. DOI: 10.2305/IUCN.UK.2007.RLTS.T64297A12756101.en

Vernacular names
Deutsch: Nordamerikanischer Kupferkopf
English: Copperhead
Nederlands: Moccasinslang
polski: Mokasyn miedziogłowiec
Türkçe: Bakır kafalı

Agkistrodon contortrix is a species of venomous snake found in North America, a member of the Crotalinae (pit viper) subfamily. Common names for the species include Copperhead and moccasin. The behavior of Agkistrodon contortrix may lead to accidental encounters with humans. Five subspecies are currently recognized, including the nominate subspecies described here.[2]

A. c. contortrix

Adults usually grow to a total length of 50–95 cm (20–37 in), although some may exceed 1 m (3.3 ft). Males are usually larger than females. The maximum length reported for this species is 134.6 cm (53.0 in) for A. c. mokasen (Ditmars, 1931). Brimley (1944) mentions a specimen of A. c. mokasen from Chapel Hill, North Carolina, that was "four feet, six inches" (137.2 cm), but this may have been an approximation. The maximum length for A. c. contortrix is 132.1 cm (52.0 in) (Conant, 1958).[3]

The body is relatively stout and the head is broad and distinct from the neck. Because the snout slopes down and back, it appears less blunt than that of the cottonmouth, A. piscivorus. Consequently, the top of the head extends further forward than the mouth.[4]

The scalation includes 21-25 (usually 23) rows of dorsal scales at midbody, 138-157 ventral scales in both sexes and 38-62/37-57 subcaudal scales in males/females. The subcaudals are usually single, but the percentage thereof decreases clinally from the northeast, where about 80% are undivided, to the southwest of the geographic range where as little as 50% may be undivided. On the head there are usually 9 large symmetrical plates, 6-10 (usually 8) supralabial scales and 8-13 (usually 10) sublabial scales.[3]

The color pattern consists of a pale tan to pinkish tan ground color that becomes darker towards the midline, overlaid with a series of 10-18 (13.4) crossbands. Characteristically, both the ground color and crossband pattern are pale in A. c. contortrix. These crossbands are light tan to pinkish tan to pale brown in the center, but darker towards the edges. They are about 2 scales wide or less at the midline of the back, but expand to a width of 6-10 scales on the sides of the body. They do not extend down to the ventral scales. Often, the crossbands are divided at the midline and alternate on either side of the body, with some individuals even having more half bands than complete ones. A series of dark brown spots is also present on the flanks, next to the belly, and are largest and darkest in the spaces between the crossbands. The belly is the same color as the ground color, but may be a little whitish in part. At the base of the tail there are 1-3 (usually 2) brown crossbands followed by a gray area. In juveniles, the pattern on the tail is more distinct: 7-9 crossbands are visible, while the tip is yellow. On the head, the crown is usually unmarked, except for a pair of small dark spots, one near the midline of each parietal scale. A faint postocular stripe is also present; diffuse above and bordered below by a narrow brown edge.[4]

Several aberrant color patterns for A. c. contortrix, or populations that intergrade with it, have also been reported. In a specimen described by Livezey (1949) from Walker County, Texas, 11 of 17 crossbands were not joined middorsally, while on one side three of the crossbands were fused together longitudinally to form a continuous undulating band, surmounted above by a dark stripe that was 2-2.5 scales wide. In another specimen, from Lowndes County, Alabama, the first three crossbands were complete, followed by a dark stripe that ran down either side of the body, with points of pigment reaching up to the midline in six places but never getting there, after which the last four crossbands on the tail were also complete. A specimen found in Terrebonne Parish, Louisiana by Ernest A. Liner, had a similar striped pattern, with only the first and last two crossbands being normal.[4]

Common names

Copperhead (snake), chunk head, death adder, highland moccasin, (dry-land) moccasin, narrow-banded copperhead, northern copperhead, pilot snake, poplar leaf, red oak, red snake, southeastern copperhead, white oak snake,[5] American copperhead,[6] southern copperhead,[4] cantil cobrizo (Spanish).[2]

Geographic range

Found in the United States in the states of Texas, Oklahoma, Kansas, Missouri, Arkansas, Louisiana, Mississippi, Alabama, Georgia, Florida, South Carolina, North Carolina, Tennessee, Kentucky, Virginia, West Virginia, Illinois, Indiana, Ohio, Iowa, Pennsylvania, Maryland, New Jersey, Delaware, New York, Connecticut and Massachusetts. In Mexico it occurs in Chihuahua and Coahuila. The type locality is "Carolina." Schmidt (1953) proposed that the type locality be restricted to "Charleston, South Carolina."[1]

Unlike some other species of North American pit vipers (Crotalus horridus and Sistrurus catenatus), Agkistrodon contortrix has not reestablished itself north of the terminal moraine after the last glacial period (the Wisconsin glaciation).[7]


Within its range it occupies a variety of different habitats. In most of North America it favors deciduous forest and mixed woodlands. It is often associated with rock outcroppings and ledges, but is also found in low-lying swampy regions. In the states around the Gulf of Mexico, however, this species is also found in coniferous forest. In the Chihuahuan Desert of west Texas and northern Mexico, it occurs in riparian habitats, usually near permanent or semipermanent water and sometimes in dry arroyos (brooks).[3]

Conservation status

This species is classified as Least Concern (LC) on the IUCN Red List of Threatened Species (v3.1, 2001).[8] Species are listed as such due to their wide distribution, presumed large population, or because it is unlikely to be declining fast enough to qualify for listing in a more threatened category. The population trend is stable. Year assessed: 2007.[9]

Southern copperhead, A. c. contortrix, at the southern limit of its range, in Liberty Co., Florida, camouflaged in dead leaves.

Like all pit vipers, A. contortrix is generally an ambush predator: it takes up a promising position and waits for suitable prey to arrive. One exception to ambush foraging occurs when copperheads feed on insects such as caterpillars and freshly molted cicadas. When hunting insects, copperheads actively pursue their prey.[10] Juveniles use a brightly colored tail to attract frogs and perhaps lizards, a behavior termed caudal luring (see video: [1]). In the southern United States, they are nocturnal during the hot summer months, but are commonly active during the day during the spring and fall.

Like most North American viperids, these snakes prefer to avoid humans and, given the opportunity, will leave the area without biting. However, unlike other viperids they will often "freeze" instead of slithering away, and as a result many bites occur from people unknowingly stepping on or near them.[11] This tendency to freeze likely evolved because of the extreme effectiveness of their camouflage. When lying on dead leaves or red clay they can be almost impossible to notice. They will frequently stay still even when approached closely, and will generally strike only if physical contact is made.


Roughly 90% of its diet consists of small rodents, such as mice and voles. They have also shown fondness for large insects and frogs, and though highly terrestrial, have been known to climb trees to gorge on emerging cicadas.


A. contortrix breeds in late summer, but not every year: sometimes a female will produce young for several years running, then not breed at all for a time. They give birth to live young about 20 cm long: a typical litter is 4 to 7, but it can be as few as one or as many as 20. Their size apart, the young are similar to the adults, but lighter in color, and with a yellow-marked tip to the tail, which is used to lure lizards and frogs.

A study has shown that A. contortrix males have longer tongue tine lengths than females during the breeding season which may aid in chemoreception of males searching for females.[12]


Although venomous, these snakes are generally non-aggressive and bites are almost never fatal. Copperhead venom has an estimated lethal dose of around 100 mg, and tests on mice show its potency is among the lowest of all pit vipers, and slightly weaker than that of its close relative, the cottonmouth. Copperheads often employ a "warning bite" when stepped on or agitated and inject a relatively small amount of venom, if any at all. "Dry bites" involving no venom are particularly common with the copperhead, though all pit vipers are capable of a dry bite.

Bite symptoms include intense pain, tingling, throbbing, swelling, and severe nausea. Damage can occur to muscle and bone tissue, especially when the bite occurs in the outer extremities such as the hands and feet, areas in which there is not a large muscle mass to absorb the venom. A bite from any venomous snake should be taken very seriously and immediate medical attention sought, as allergic reaction and secondary infection are always possible.

The venom of the Southern copperhead has been found to hold a protein called "Contortrostatin" that halts the growth of cancer cells and also stops the migration of the tumors to other sites. It will probably be ten or more years before contortrostatin is used in practical treatment but it has shown to be a very promising drug in laboratory studies.

Although technically the antivenin CroFab could be used to treat an envenomation, it is usually not administered for copperheads, as the risk of complications of an allergic reaction to the treatment are greater than the risk from the snakebite itself in most cases. Pain management, antibiotics, and medical supervision in the case of complications is usually the course of action.[13] In 2002 the Illinois poison control center report on the availability of antivenin, the report stated it used 1 Acp to 5 Acp depending on the symptoms and circumstances. The symptoms of a mild envenomation include swelling of the hand, mild cellulitis, and respiratory distress. The symptoms of a moderate envenomation would include swelling of the hand, vomiting, mild bleeding, ecchymosis, diaphoretic, sinus tachycardia, and hypotensive, where the most likely circumstance is the person bitten was collecting rocks.


Subspecies[2] Taxon author[2] Common name[4] Geographic range[4]
A. c. contortrix (Linnaeus, 1766) Southern copperhead The United States, in the lower Mississippi Valley and the states bordering the Gulf of Mexico, from eastern Texas and southeastern Oklahoma to southern Illinois. On the South Atlantic Coastal Plain from the Florida panhandle to South Carolina.
A. c. laticinctus Gloyd & Conant, 1934 Broad-banded copperhead The United States, from south-central Texas (Victoria to Frio counties), north through central Oklahoma to the extreme south of Cowley County, Kansas.
A. c. mokasen Palisot de Beauvois, 1799 Northern copperhead The United States, in southern Illinois, extreme northeastern Mississippi, northern Alabama, northern Georgia northeast to Massachusetts, the Appalachian Mountain region and associated plateaus.
A. c. phaeogaster Gloyd, 1969 Osage copperhead The United States, in eastern Kansas, extreme southeastern Nebraska and a large part of Missouri.
A. c. pictigaster Gloyd & Conant, 1943 Trans-pecos copperhead The United States, in western Texas from the vicinity of the Pecos and Devils rivers to the counties of Jeff Davis and Presidio. Mexico, in northern Chihuahua and Coahuila.

Popular culture

During the American Civil War the leading Peace Democrats were called Copperheads.

In 2010, small arms maker Sig Sauer named a limited edition .380ACP pistol P238 Copperhead. (


^ a b 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).
^ a b c d "Agkistrodon contortrix". Integrated Taxonomic Information System. Retrieved 28 November 2006.
^ a b c Campbell JA, Lamar WW. 2004. The Venomous Reptiles of the Western Hemisphere. Comstock Publishing Associates, Ithaca and London. 870 pp. 1500 plates. ISBN 0-8014-4141-2.
^ a b c d e f Gloyd HK, Conant R. 1990. Snakes of the Agkistrodon Complex: A Monographic Review. Society for the Study of Amphibians and Reptiles. 614 pp. 52 plates. LCCN 89-50342. ISBN 0-916984-20-6.
^ Wright AH, Wright AA. 1957. Handbook of Snakes. Comstock Publishing Associates. (7th printing, 1985). 1105 pp. ISBN 0-8014-0463-0 .
^ U.S. Navy. 1991. Poisonous Snakes of the World. US Govt. New York: Dover Publications Inc. 203 pp. ISBN 0-486-26629-X.
^ anonymous. (year?). Copperhead Snake, Life History Notes. Ohio Division of Wildlife. Publication 373 (399).
^ Agkistrodon contortrix at the IUCN Red List. Accessed 13 September 2007.
^ 2001 Categories & Criteria (version 3.1) at the IUCN Red List. Accessed 13 September 2007.
^ Reiserer, R. S. 2002. Stimulus control of caudal luring and other feeding responses: A program for research on visual perception in vipers, Pp. 361-383 in Schuett, G.W., M. Höggren, M. E. Douglas, and H. W. Greene (eds.), Biology of the Vipers, Eagle Mountain Publishing, Eagle Mtn., Utah.
^ "Venomous Snakes". National Institute for Occupational Safety and Health. Retrieved on November 10, 2008.
^ Smith, C.F., K. Schwenk , R. L. Earley , and G. W. Schuett. 2008. Sexual size dimorphism of the tongue in a North American pitviper. Journal of Zoology. 274(4): 367 - 374.

Further reading

Brimley CS. 1944. Amphibians and reptiles of North Carolina. Elon College, North Carolina, Carolina Biol. Supply Co., reprinted from Carolina Tips, 1939-43: 1-63.
Conant R. 1958. A field guide to reptiles and amphibians of the United States and Canada east of the 100th meridian. Boston, Massachusetts, Houghton, Mifflin Co.: i-xv, 1-366.
Livezey RL. 1949. An aberrant pattern of Agkistrodon mokeson austrinus. Herpetologica, 5: 93.

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