Coral snake

From Wikipedia, the free encyclopedia
Jump to navigation Jump to search

Coral snake
Coral snake.jpg
Coral snake (Micrurus sp.)
Scientific classification e
Kingdom: Animalia
Phylum: Chordata
Class: Reptilia
Order: Squamata
Suborder: Serpentes
Superfamily: Elapoidea
Family: Elapidae

Coral snakes are a large group of elapid snakes that can be subdivided into two distinct groups, Old World coral snakes and New World coral snakes. There are 16 species of Old World coral snake 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 are Asian, indicating that the group originated in the Old World.[1][2]

North American coloration patterns[edit]

Experts now recognize that coloration patterns and common mnemonics which people use to identify the deadly coral snake are occasionally inconsistent. While any North American snake exhibiting the coral snake's color banding pattern will almost certainly in fact be a coral snake (with one exception), there are coral snakes in other parts of the world which are colored differently.[3] Examples of mnemonics commonly used to sort North American coral snakes from similarly-colored but non-venomous local species include the following:

  • "Red'n Yellow Deadly Fellow, Red'n Black Friend of Jack" "Red on yellow kills a fellow. Red on black, venom lack." or "Red touches black, it’s a friend of Jack. Red touches yellow, it’s bad for a fellow." or "Red touches yellow, you're a dead fellow. Red touches black, you're okay Jack."[4][5]

Coral snakes in North America are most notable for their red, yellow/white, and black colored banding. However, several nonvenomous species have similar (though not identical) coloration, including the scarlet snake, genus Cemophora; some of the kingsnakes, and the milk snakes, genus Lampropeltis, whose banding however does not include any red touching any yellow; also, there is a genus of shovelnose snake, genus Chionactis, whose color banding actually matches that of a genuine coral snake. No genuine coral snakes in North America, however, exhibit red bands of color in contact with bands of black. So while on extremely rare occasions a certain non-venomous snake might be mistaken for a coral snake, the mnemonic holds true in that a red/ yellow/ black banded snake in North America whose red banding is in contact with its black banding is never a poisonous coral snake.

Most species of coral snake are small in size. North American species average around 3 feet (91 cm) in length, but specimens of up to 5 feet (150 cm) or slightly larger have been reported. Aquatic species have flattened tails acting as a fin, aiding in swimming.

Behavior[edit]

Coral snake showing typically reclusive behavior of hiding under rotting wood. This one was over 30 inches (76 cm) long, but less than an inch (2.5 cm) across.

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.[6][7] 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.[8][9] 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.[8][10] The venom takes time to reach full effect.[9]

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.[11]

Distribution (U.S.)[edit]

Eastern coral snake (Micrurus fulvius)

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.[12]

There is controversy about the classification of the very similar Texas coral snake as a separate species. Its habitat, in Texas, Louisiana, Arkansas, and sometimes in Oklahoma due to floods in the Red River, 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.[13]

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 from sea level to 5,800 feet (1,768 m); often found in rocky areas.[14]

Danger to humans[edit]

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. According to the American National Institutes of Health, there is an average of 15–25 coral snake bites in the United States each year.[15] When confronted by humans, coral snakes will almost always attempt to flee, and bite only as a last resort. In addition, coral snakes have short fangs (proteroglyph dentition) that cannot penetrate thick leather clothing. Any skin penetration, however, is a medical emergency that requires immediate attention. The powerful neurotoxin in the venom paralyzes the breathing muscles, often requiring mechanical or artificial respiration and large doses of antivenom to save a victim's life. Though there is usually only mild pain associated with a bite, respiratory failure can occur within hours.

Antivenom shortage[edit]

As of 2012, the relative rarity of coral snake bites, combined with the high costs of producing and maintaining an antivenom supply, means that antivenom (also called "antivenin") production in the United States has ceased. According to Pfizer, the owner of the company that used to make the antivenom Coralmyn, it would take between $5–$10 million for researching a new synthetic antivenom.[citation needed][clarification needed] The cost was too high in comparison to the small number of cases presented each year. The existing American coral snake antivenom stock technically expired in 2008, but the U.S. Food and Drug Administration has extended the expiration date every year through to at least 30 April 2017.[16][17] Foreign pharmaceutical manufacturers have produced other coral snake antivenoms, but the costs of licensing them in the United States have stalled availability (see above).[18] Instituto Bioclon is developing a coral snake antivenom.[19] In 2013, Pfizer was reportedly working on a new batch of antivenom but had not announced when it would become available.[17] As of 2016, the Venom Immunochemistry, Pharmacology and Emergency Response (VIPER) institute of the University of Arizona College of Medicine was enrolling participants in a clinical trial of INA2013, a "novel antivenom," according to the Florida Poison Information Center.[20][21]

Old World[edit]

Genus Calliophis[edit]

Species in this genus are:

Nota bene: A binomial authority in parentheses indicates that the species was originally described in a different genus.

Genus Hemibungarus[edit]

Species in this genus are:

Genus Sinomicrurus[edit]

Species in this genus are:

New World[edit]

Genus Micruroides[edit]

Genus Micrurus[edit]

Mimicry[edit]

New World coral snakes serve as models for their Batesian mimics, false coral snakes, snake species whose venom is less toxic, as well as for many nonvenomous snake species that bear superficial resemblances to them. The role of coral snakes as models for Batesian mimics is supported by research showing that coral snake color patterns deter predators from attacking snake-shaped prey,[22][23] and that in the absence of coral snakes, species hypothesized to mimic them are indeed attacked more frequently.[24] Species that appear similar to coral snakes include:

References[edit]

  1. ^ Slowinski, J. B. & Keogh J. S. (April 2000). "Phylogenetic Relationships of Elapid Snakes Based on Cytochrome b mtDNA Sequences". Molecular Phylogenetics and Evolution. 15 (1): 157–164. doi:10.1006/mpev.1999.0725. PMID 10764543.
  2. ^ Slowinski, J. B.; Boundy, J. & Lawson, R. (June 2001). "The phylogenetic relationships of Asian coral snakes (Elapidae: Calliophis and Maticora) based on morphological and molecular characters". Herpetologica. 57 (2): 233–245. JSTOR 3893186.
  3. ^ "The Most Common Myths About Coral Snakes | The Venom Interviews". thevenominterviews.com. Retrieved 7 October 2018.
  4. ^ "Frequently Asked Questions". South Carolina Department of Natural Resources. (see FAQ's. -- "are there any visual clues"..........). Archived from the original on 30 December 2017.
  5. ^ Medical-Surgical Nursing: Patient-Centered Collaborative Care   by Donna D. Ignatavicius, M. Linda Workman   (page 125s)
  6. ^ Eastern Coral Snake (Micrurus fulvius), Savannah River Ecology Library.
  7. ^ Coral Snakes: Rear fanged? Grooved fangs? Primitive?
  8. ^ a b Eastern Coral Snake
  9. ^ a b "Coral Snakes: Micrurus f. fulvius". Retrieved 24 November 2009.
  10. ^ Coral Snakes: Colors, Bites, Farts & Facts, Live Science.
  11. ^ "Eastern Coral Snake". Animals national Geographic.
  12. ^ University of Georgia, Savannah River Ecology, Snakes of Georgia and South Carolina
  13. ^ Western Connecticut State University
  14. ^ Arizona-Sonora Desert Museum
  15. ^ "Snake bites: MedlinePlus Medical Encyclopedia". Nlm.nih.gov. 13 January 2010. Retrieved 16 November 2010.
  16. ^ "Safety & Availability (Biologics) > Expiration Date Extension for North American Coral Snake Antivenin (Micrurus fulvius) (Equine Origin) Lot 4030026 Through October 31, 2014". Food and Drug Administration. Retrieved 19 March 2016.
  17. ^ a b Breen, David (12 October 2013). "Risk from coral-snake bites grows as antivenin dwindles". Orlando Sentinel. Retrieved 25 May 2014.
  18. ^ "Antivenom Shortages – Cost of Antivenom Production Creates Shortages". Popular Mechanics. 10 May 2010. Retrieved 16 November 2010.
  19. ^ "Our Products – Coralmyn". Bioclon.com.mx. Archived from the original on 13 October 2010. Retrieved 16 November 2010.
  20. ^ "Coral Snake Antivenom - Poison Center Tampa". Poison Center Tampa. Retrieved 19 March 2016.
  21. ^ "Emergency Treatment of Coral Snake Envenomation With Antivenom - Full Text View - ClinicalTrials.gov". National Institutes of Health. Retrieved 19 March 2016.
  22. ^ Brodie III, Edmund D (1993). "Differential avoidance of coral snake banded patterns by free-ranging avian predators in Costa Rica". Evolution. 47 (1): 227–235. doi:10.2307/2410131. JSTOR 2410131. PMID 28568087.
  23. ^ Brodie III, Edmund D.; Moore, Allen J. (1995). "Experimental studies of coral snake mimicry: do snakes mimic millipedes?". Animal Behaviour. 49 (2): 534–6. doi:10.1006/anbe.1995.0072. S2CID 14576682.
  24. ^ Pfennig, David W.; Harcombe, William R.; Pfennig, Karin S. (2001). "Frequency-dependent Batesian mimicry". Nature. 410 (6826): 323. Bibcode:2001Natur.410..323P. doi:10.1038/35066628. PMID 11268195. S2CID 205015058.

Further reading[edit]

  • Boulenger, G.A. 1896. Catalogue of the Snakes in the British Museum (Natural History). Volume III., Containing the Colubridæ (Opisthoglyphæ and Proteroglyphæ)... Trustees of the British Museum (Natural History). (Taylor and Francis, Printers.) London. xiv + 727 pp. + Plates I.- XXV. (Elaps, 28 species, pp. 411–433 + Plate XX.)
  • Roze, J.A. 1996. Coral Snakes of the Americas: Biology, Identification, and Venoms. Krieger. Malabar, Florida. 340 pp. ISBN 978-0894648472.
  • Tanaka G. D., Furtado Md. F. D., Portaro F. C. V., Sant'Anna O. A. & Tambourgi D. V. (2010). "Diversity of Micrurus Snake Species Related to Their Venom Toxic Effects and the Prospective of Antivenom Neutralization". PLoS Neglected Tropical Diseases 4(3): e622. doi:10.1371/journal.pntd.0000622
  • Universidad de Costa Rica (2009). El envenenamiento por mordedura de serpiente en Centroamérica ("Snakebite poisonings in Central America"). San José, Costa Rica: Instituto Clodomiro Picado, Facultad de Microbiología, Universidad de Costa Rica. (in Spanish)