Coral snake

Coral snakes are a large group of elapid snakes that can be divided into two distinct groups, the Old World coral snakes and New World coral snakes. There are 16 species of Old World coral snakes, in three genera (''Calliophis'', '' Hemibungarus'', and '' Sinomicrurus''), and over 65 recognized species of New World coral snakes, in two genera ('' Micruroides'' and ''Micrurus''). Genetic studies have found that the most basal lineages have origins in Asia, suggesting that the group originated in the Old World. While new world species of both genera are venomous, their bites are seldom lethal; only two confirmed fatalities have been documented in the past 100 years from the genus ''Micrurus''. Meanwhile, snakes of the genus ''Micruroides'' have never caused a medically-significant bite.

North American coloration patterns

Experts now recognize that certain coloration patterns and common mnemonics - such as the phrase “Red touch yellow, kill a fellow; red touch black, you’re good, Jack,” which people sometimes use to distinguish between the venomous coral snake & non-venomous milksnake - are not consistent enough to be trustworthy. While any snake exhibiting the coral snake's color and/or banding pattern in the southeastern United States will almost certainly, in fact, be a coral snake, there are coral snakes in other parts of the world which are colored differently.

Coral snakes in the United States are most notable for their red, yellow/white, and black-colored banding. However, several nonvenomous species in the U.S. have similar (though not identical) bandings, including the two scarlet snake species in the genus ''Cemophora'', and some of the kingsnakes (including the aforementioned milksnakes) in the genus ''Lampropeltis''. However, in reference to the mnemonic phrase “red touching yellow, a deadly fellow,” some of these kingsnakes do not naturally display any red touching yellow, to begin with. Additionally, some ground snakes in the genus '' Sonora'' (of the southwestern U.S.) can have a color pattern that matches that of the sympatric Sonoran coral snake (''Micruroides euryxanthus''). No genuine coral snake in the U.S. exhibits red bands of color, in contact with bands of black, except in rare cases of an aberrant pattern. Thus, while on extremely rare occasions when a certain non-venomous snake might be mistaken for a coral snake, the mnemonic holds true. However, a red–yellow–black banded snake in the U.S. (whose red and black banding actually touch) is rarely a venomous coral snake.

Furthermore, the mnemonic is not consistently accurate for North American coral snake species found south of the U.S., either. Some species, like Mexico’s Oaxacan coral snake (''Micrurus ephippifer'') or Clark's coral snake (''Micrurus clarki'', of Costa Rica & Panama), do actually fit the mnemonic; others, like the Mexican saddled coral snake (''Micrurus bernadi''), the Honduran Roatan coral snake (''Micrurus ruatanus''), or the redtail coral snake (''Micrurus mipartitus'') of Panama, do not. Further still, some South American coral snakes will fit the mnemonic, while others do not. To complicate the issue more, the South American tricolored hognose snake (''Xenodon pulcher'') has repeated bands of red-black-white-black, imitating the coral snake as a defense mechanism, with the key visual difference being their upturned snout (used for burrowing). The hognoses are, actually, mildly rear-fanged venomous; although generally not considered serious to humans, anecdotal research has suggested the South American hognoses to possess slightly more potent venom than the North American hognoses. In the Old World, none of the coral snake species usually fit the mnemonic.

Most species of coral snake are small in size. North American species average around in length, but specimens of up to or slightly larger have been reported. Some coral snakes even live in the water but most of them do not. Aquatic species have flattened tails that act as fins, aiding in swimming.

Behavior

Coral snakes vary widely in their behavior, but most are very elusive, fossorial (burrowing) snakes which spend most of their time buried beneath the ground or in the leaf litter of a rainforest floor, coming to the surface only when it rains or during breeding season. Some species, like ''Micrurus surinamensis'', are almost entirely aquatic and spend most of their lives in slow-moving bodies of water that have dense vegetation.

Coral snakes feed mostly on smaller snakes, lizards, frogs, nestling birds, small rodents, etc.

Like all elapid snakes, coral snakes possess a pair of small hollow fangs to deliver their venom. The fangs are positioned at the front of the mouth. The fangs are fixed in position rather than retractable, and rather than being directly connected to the venom duct, they have a small groove through which the venom enters the base of the fangs. Because the fangs are relatively small and inefficient for venom delivery, rather than biting quickly and letting go (like vipers), coral snakes tend to hold onto their prey and make chewing motions when biting. The venom takes time to reach full effect.

Coral snakes are not aggressive or prone to biting and account for less than one percent of the total number of snake bites each year in the United States. The life span of coral snakes in captivity is about seven years.

Reproduction

''M. fluvius'' reproduction is internal fertilization through the use of hemipenes. The breeding season occurs from spring to early summer and late summer to early fall. Male combat is not typical in ''M. fulvius'' as males are smaller than females. ''Micrurus fulvius'' are oviparous and typically lay eggs from May to July. During early spring females will undergo sudden vitellogenesis–oocyte and yolk formation–in preparation for breeding. Approximately 37 days post fertilization oviposition occurs and the average clutch size ranges from five to seven eggs. The incubation period of the ''M. fluvius'' eggs normally reaches 60 days. Males also undergo sexual changes throughout the year, testicular recrudescence start in the fall and testicular regression occurs come spring. However, males typically have mature sperm residing in the epididymis year round and are capable of storing sperm in the deferent duct over the winter till the females are receptive. A study investigating how climate influences the reproductive cycle discovered species found closer to the equator displayed more continuous cycles while those in colder regions had more seasonal cycles. With increasing temperatures as a result of climate change, continuous cycles have the possibility of becoming more prevalent. Offspring reach maturation depending on sex, males mature at roughly 11 to 16 months while females reach maturity later at 26 months. With increasing temperatures as a result of climate change continuous cycles have the possibility of becoming more prevalent.

Distribution (U.S.)

New World coral snakes exist in the southern range of many temperate U.S. states. Coral snakes are found in scattered localities in the southern coastal plains from North Carolina to Louisiana, including all of Florida. They can be found in pine and scrub oak sandhill habitats in parts of this range, but sometimes inhabit hardwood areas and pine flatwoods that undergo seasonal flooding.

There is controversy about the classification of the very similar Texas coral snake as a separate species. Its habitat, in Texas, Louisiana, and Arkansas is separated from the eastern coral snake's habitat by the Mississippi River. The coral snake population is most dense in the southeastern United States, but coral snakes have been documented as far north as Kentucky.

The Arizona coral snake is classified as a separate species and genus and is found in central and southern Arizona, extreme southwestern New Mexico and southward to Sinaloa in western Mexico. It occupies arid and semiarid regions in many different habitat types, including thornscrub, desert-scrub, woodland, grassland and farmland. It is found in the plains and lower mountain slopes, at elevations ranging from sea level to ; often found in rocky areas.

Danger to humans

New World coral snakes possess one of the most potent venoms of any North American snake. However, relatively few bites are recorded due to their reclusive nature and the fact they generally inhabit sparsely populated areas. Even in areas that are densely populated bites are rare. According to the American National Institutes of Health, there are an average of 15–25 coral snake bites in the United States each year.
When confronted by humans, coral snakes will almost always attempt to flee, and bite only if restrained. In addition, coral snakes have short fangs ( proteroglyph dentition) that cannot penetrate thick clothing although bites are possible through normal thin clothing. Any skin penetration, however, is a medical emergency that requires immediate attention.

Historically, the venom of the North American ''Micrurus'' and ''Micruroides'' species was believed to contain powerful neurotoxins which could paralyze the breathing muscles, requiring mechanical or artificial respiration. It was usually reported that there was only mild pain associated with a bite and that respiratory failure could occur within hours. However recent studies on the bites of at least the Texas Coralsnake (''Micrurus tener'') have shown that these bites rarely require antivenom, don't usually show any systemic respiratory problems and can be intensely painful. Further studies are necessary to see if these clinical features are true of all ''Micrurus'' species.

Shortages of coral snake antivenin were previously reported, but one source states that production has resumed and, Pfizer indicates that antivenin is available.

Old World

Genus ''Calliophis''

Species in this genus are:
*''Calliophis beddomei'' ( M.A. Smith, 1943) – Beddome's coral snake (India)
*'' Calliophis bibroni'' ( Jan, 1858) – Bibron's coral snake (India)
*'' Calliophis bivirgatus'' ( F. Boie, 1827) – blue Malaysian coral snake (Indonesia, Cambodia, Malaysia, Singapore, Thailand)
*'' Calliophis castoe'' (E.N. Smith, Ogale, Deepak & Giri, 2012) – Castoe's coral snake (India)
*''Calliophis gracilis'' ( Gray, 1835) – spotted coral snake (Thailand, Malaysia, Indonesia, Singapore)
*'' Calliophis haematoetron'' (E.N. Smith, Manamendra-Arachchi & Somweera, 2008) – blood-bellied coral snake ( Sri Lanka)
*'' Calliophis intestinalis'' ( Laurenti, 1768) – banded Malaysian coral snake (Indonesia, Malaysia)
*''Calliophis maculiceps'' ( Günther, 1858) – speckled coral snake (Myanmar, Thailand, Malaysia, Vietnam, Cambodia, Laos)
*'' Calliophis melanurus'' ( Shaw, 1802) – Indian coral snake (India, Bangladesh, Sri Lanka)
*''Calliophis nigrescens'' (Günther, 1862) – black coral snake (India)
*''Calliophis salitan'' (Brown, Smart, Leviton & Smith, 2018) – Dinagat Island Banded Coralsnake (Philippines)

Genus ''Hemibungarus''

Species in this genus are:
*'' Hemibungarus calligaster'' ( Wiegmann, 1835) – barred coral snake (Philippines)
*''Hemibungarus gemianulis'' (Peters, 1872) – (Philippines)

Genus ''Sinomicrurus''

Species in this genus are:
*''Sinomicrurus hatori'' (Takahashi, 1930) (Taiwan)
*''Sinomicrurus japonicus'' ( Günther, 1868) – Japanese coral snake ( Ryukyu Islands)
*'' Sinomicrurus kelloggi'' ( Pope, 1928) – Kellogg's coral snake (Vietnam, Laos, China)
*'' Sinomicrurus macclellandi'' ( J.T. Reinhardt, 1844) – Macclelland's coral snake (India, Nepal, Myanmar, Thailand, Vietnam, China, Ryukyu Islands, Taiwan)
*''Sinomicrurus sauteri'' ( Steindachner, 1913) (Taiwan)

New World

Genus '' Micruroides''

*'' Micruroides euryxanthus'' ( Kennicott, 1860) – Arizona coral snake (lowland regions from Arizona to Sinaloa, Mexico)
**''Micruroides euryxanthus australis'' ( Zweifel & Norris, 1955)
**''Micruroides euryxanthus euryxanthus'' ( Kennicott, 1860)
**''Micruroides euryxanthus neglectus'' ( Roze, 1967)

Genus ''

Micrurus''

*''Micrurus albicinctus'' (Amaral, 1925) – White-banded Coral Snake
*''Micrurus alleni'' ( K.P. Schmidt, 1936) – Allen's coral snake (eastern Nicaragua, Costa Rica, and Panama)
**''Micrurus alleni alleni'' (K.P. Schmidt, 1936)
**'' Micrurus alleni richardi'' ( Taylor, 1951)
**''Micrurus alleni yatesi'' (Taylor, 1954)
*''Micrurus altirostris'' (Cope, 1860) (Brazil, Uruguay, and northeastern Argentina)
*'' Micrurus ancoralis'' ( Jan, 1872) – regal coral snake (southeastern Panama, western Colombia, and western Ecuador)
**''Micrurus ancoralis ancoralis'' (Jan 1872)
**''Micrurus ancoralis jani'' (K.P. Schmidt, 1936)
*''Micrurus annellatus'' ( W. Peters, 1871) – annellated coral snake (southeastern Ecuador, eastern Peru, Bolivia, and western Brazil)
**''Micrurus annellatus annellatus'' (W. Peters, 1871)
**''Micrurus annellatus balzanii'' ( Boulenger, 1898)
**''Micrurus annellatus bolivianus'' ( Roze, 1967)
*''Micrurus averyi'' (K.P. Schmidt, 1939) – black-headed coral snake
*''Micrurus baliocoryphus'' (Cope, 1860) – Mesopotamian coral snake
*''Micrurus bernadi'' (Cope, 1887) (Mexico)
*''Micrurus bocourti'' (Jan 1872) – Ecuadorian coral snake (western Ecuador to northern Colombia)
*''Micrurus bogerti'' (Roze, 1967) – Bogert's coral snake (Oaxaca)
*''Micrurus boicora'' (Bernarde, Turci, Abegg & Franco, 2018) – Boicora Coral Snake
*''Micrurus brasiliensis'' (Roze, 1967) – Brazilian short-tailed coral snake
*''Micrurus browni'' (K.P. Schmidt & H.M. Smith, 1943) – Brown's coral snake (Quintana Roo to Honduras)
**''Micrurus browni browni'' (K.P. Schmidt & H.M. Smith, 1943)
**''Micrurus browni importunus'' (Roze, 1967)
**''Micrurus browni taylori'' (K.P. Schmidt & H.M. Smith, 1943)
*''Micrurus camilae'' (Renjifo & Lundberg, 2003) ( Colombia)
*''Micrurus catamayensis'' (Roze, 1989) – Catamayo coral snake (Catamayo Valley of Ecuador)
*''Micrurus clarki'' (K.P. Schmidt, 1936) – Clark's coral snake (southeastern Costa Rica to western Colombia)
*''Micrurus collaris'' (Schlegel, 1837) – Guyana blackback coral snake (northern South America)
** ''Micrurus collaris collaris'' (Schlegel, 1837)
** ''Micrurus collaris breviventris'' ( Roze & Bernal-Carlo, 1987)
*''Micrurus corallinus'' ( Merrem, 1820) – painted coral snake
*''Micrurus decoratus'' (Jan 1858) – Brazilian coral snake
*'' Micrurus diana'' (Roze, 1983)
*''Micrurus diastema'' ( A.M.C. Duméril, Bibron & A.H.A. Duméril, 1854) – variable coral snake
**''Micrurus diastema aglaeope'' (Cope, 1859)
**''Micrurus diastema alienus'' ( F. Werner, 1903)
**''Micrurus diastema affinis'' (Jan 1858)
**''Micrurus diastema apiatus'' (Jan 1858)
**''Micrurus diastema diastema'' (A.M.C. Duméril, Bibron & A.H.A. Duméril, 1854)
**'' Micrurus diastema macdougalli'' (Roze, 1967)
**''Micrurus diastema sapperi'' (F. Werner, 1903)
*''Micrurus dissoleucus'' (Cope, 1860) – pygmy coral snake
**''Micrurus dissoleucus dissoleucus'' (Cope, 1860)
**''Micrurus dissoleucus dunni'' ( Barbour, 1923)
**'' Micrurus dissoleucus melanogenys'' (Cope, 1860)
**''Micrurus dissoleucus meridensis'' (Roze, 1989)
**'' Micrurus dissoleucus nigrirostris'' (K.P. Schmidt, 1955)
*''Micrurus distans'' ( Kennicott, 1860) – West Mexican coral snake
**''Micrurus distans distans'' (Kennicott, 1860)
**''Micrurus distans michoacanensis'' ( Dugės, 1891)
**''Micrurus distans oliveri'' (Roze, 1967)
**''Micrurus distans zweifeli'' (Roze, 1967)
*'' Micrurus diutius'' (Burgur, 1955) – Trinidad Ribbon Coral Snake
*''Micrurus dumerilii'' (Jan 1858)
**''Micrurus dumerilii antioquiensis'' (K.P. Schmidt, 1936)
**''Micrurus dumerilii carinicaudus'' (K.P. Schmidt, 1936)
**''Micrurus dumerilii colombianus'' ( Griffin, 1916)
**''Micrurus dumerilii dumerilii'' (Jan 1858)
**''Micrurus dumerilii transandinus'' (K.P. Schmidt, 1936)
**''Micrurus dumerilii venezuelensis'' (Roze, 1989)
*'' Micrurus elegans'' (Jan 1858) – elegant coral snake
**'' Micrurus elegans elegans'' (Jan 1858)
**''Micrurus elegans veraepacis'' (K.P. Schmidt, 1933)
*''Micrurus ephippifer'' (Cope, 1886) – Oaxacan coral snake
**'' Micrurus ephippifer ephippifer'' (Cope, 1886)
**''Micrurus ephippifer zapotecus'' (Roze, 1989)
*''Micrurus filiformis'' ( Günther, 1859) – slender coral snake
**''Micrurus filiformis filiformis'' (Günther, 1859)
**''Micrurus filiformis subtilis'' (Roze, 1967)
*''Micrurus frontalis'' (A.M.C. Duméril, Bibron & A.H.A. Duméril, 1854) – southern coral snake (Brazil to northeastern Argentina)
**''Micrurus frontalis frontalis'' (A.M.C. Duméril, Bibron & A.H.A. Duméril, 1854)
**'' Micrurus frontalis mesopotamicus'' (Barrio & Miranda 19)
*''Micrurus fulvius'' (Linnaeus, 1766) – eastern coral snake (U.S. coastal plains of North Carolina to Louisiana)
*''Micrurus hemprichii'' (Jan 1858) – Hemprich's coral snake
**''Micrurus hemprichii hemprichii'' (Jan 1858)
**'' Micrurus hemprichii ortoni'' (K.P. Schmidt, 1953)
**''Micrurus hemprichii rondonianus'' (Roze & da Silva, 1990)
*''Micrurus hippocrepis

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