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Coral snake

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Coral Snake
Coral snake (Micrurus sp.)
Scientific classification
Kingdom:
Animalia
Phylum:
Chordata
Class:
Reptilia
Order:
Squamata
Suborder:
Serpentes
Family:
Elapidae
Species

See text.

The 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 11 species of Old World coral snake in one genus (Calliophis), and over 65 recognized species of New World coral snakes in three genera (Leptomicrurus, Micruroides, and Micrurus).

North American coloration patterns

Coral snakes are most notable for their red, yellow/white, and black colored banding. (However, several nonvenomous species have similar coloration, including the scarlet snake, genus Cemophora, some of the kingsnakes and milk snakes, genus Lampropeltis, and the shovelnose snakes, genus Chionactis.) In some regions, the order of the bands distinguishes between the non-venomous mimics and the venomous coral snakes, inspiring some folk rhymes — "Red on yellow, kill a fellow; "Red on black, friend of Jack"; and "Red into black, venom lack; red into yellow, kill a fellow." However, this reliably applies only to coral snakes native to North America: Micrurus fulvius (Eastern or common coral snake), Micrurus tener (Texas coral snake), and Micruroides euryxanthus (Arizona coral snake), found in the southern and western United States. Coral snakes found in other parts of the world can have distinctly different patterns, have red bands touching black bands, have only pink and blue banding, or have no banding at all.


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

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

Coral snakes vary widely in their behavior, but most are very elusive, fossorial snakes which spend the vast majority of their time buried beneath the ground or in the leaf litter of a rainforest floor, only coming to the surface while raining 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.

Like all elapid snakes, coral snakes use a pair of small fangs fixed in the front of their top jaw to deliver their venom. They feed on smaller snakes, lizards, frogs, and nestling birds and rodents etc. The venom takes time to fully take effect.[1]

Coral snakes have a tendency to hold on to a victim when biting, unlike vipers which have retractable fangs and tend to prefer to strike and let go immediately. Coral snakes are not aggressive or prone to biting however, and account for less than one percent of the number of snake bites each year in the United States. Most coral snake bites in the United States are legitimate occurring because of accidental contact with the snake while engaged in an outdoor activity such as gardening.

Distribution

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 Plain from North Carolina to Louisiana, including all of Florida. They can be found in pine and scrub oak sandhills habitats in parts of this range but sometimes inhabit hardwood areas and pine flatwoods that undergo seasonal flooding.[2]

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 habitat by the Mississippi River. The map here shows the denser population in the southeast United States but coral snakes have been spotted as far north as Kentucky.[3]

The Arizona coral snake, clearly a separate species and genus, 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 5800 feet (1768 m); often found in rocky areas. [4]

Danger to humans

New World coral snakes possess one of the most potent venoms of any North American snake. Most venomous snakes must inject between 75–100 mg of venom to be fatal.[5] 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 are an average of only 15-25 coral snake bites in the United States each year.[6]

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. Coral snakes have a powerful neurotoxin that paralyzes the breathing muscles; mechanical or artificial respiration, along with large doses of antivenin, are often required to save a victim's life. There is usually only mild pain associated with a bite, but respiratory failure can occur within hours.

The bite of a coral snake may soon become increasingly more dangerous, ironically because of the relatively few bites each year. Production of coral snake antivenin in the United States has ceased because it is not profitable. According to Pfizer, the owner of the company that used to make Coralmyn, it would take over $5–$10 million to put toward researching a new synthetic antivenin. The cost was just too large for the small number of cases presented each year. The current antivenin stock is scheduled to expire in 2010, after two consecutive expiration date extensions approved by the FDA. Foreign pharmaceutical manufacturers have produced other coral snake antivenins, but the costs associated with licensing them in the United States have stalled availability (see above).[7]

Coral snake antivenom

Instituto Bioclon is developing a Coral Snake Antivenom.[8]

Taxonomy

Animalia, Deuterostomia, Chordata - Vertebrata - Gnathostomata, Reptilia, Squamata, Serpentes, Elapidae

Old World

Genus Calliophis

Main article: Calliophis
Wikispecies has information related to Calliophis.

New World

Genus Leptomicrurus

  • Leptomicrurus collaris collaris (Schlegel, 1837)
  • Leptomicrurus collaris breviventris (Roze & Bernal-Carlo, 1987)
  • Leptomicrurus narduccii narduccii (Jan, 1863)
  • Leptomicrurus narduccii melanotus (Peters, 1881)

Genus Micruroides

Wikispecies has information related to Micruroides.
  • Micruroides euryxanthus australis (Zweifel & Norris, 1955)
  • Micruroides euryxanthus euryxanthus (Kennicott, 1860)
  • Micruroides euryxanthus neglectus (Roze, 1967)

Genus Micrurus

Wikispecies has information related to Micrurus.
  • Micrurus alleni alleni (Schmidt, 1936)
  • Micrurus alleni richardi (Taylor, 1951)
  • Micrurus alleni yatesi (Taylor, 1954)
  • Micrurus ancoralis jani (Schmidt, 1936)
  • Micrurus ancoralis ancoralis (Jan, 1872)
  • Micrurus annellatus annellatus (Peters, 1871)
  • Micrurus annellatus balzanii (Boulenger, 1898)
  • Micrurus annellatus bolivianus (Roze, 1967)

Mimicry

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,[9][10] and that in the absence of coral snakes, species hypothesized to mimic them are indeed attacked more frequently.[11] Species that appear similar to coral snakes include:

Notes

  1. ^ "Coral Snakes, coral snake, pictures". Retrieved 24 November 2009.
  2. ^ University of Georgia, Savannah River Ecology, Snakes of Georgia and South Carolina
  3. ^ Western Connecticut State University
  4. ^ Arizona-Sonora Desert Museum
  5. ^ "The Venomous Reptiles of the Western Hemisphere". Venomousreptiles.org. Retrieved 16 November 2010.
  6. ^ "Snake bites: MedlinePlus Medical Encyclopedia". Nlm.nih.gov. 13 January 2010. Retrieved 16 November 2010.
  7. ^ "Antivenom Shortages - Cost of Antivenom Production Creates Shortages". Popular Mechanics. 10 May 2010. Retrieved 16 November 2010.
  8. ^ "Our Products - Coralmyn". Bioclon.com.mx. Retrieved 16 November 2010.
  9. ^ Brodie III, Edmund D. (1993). "Differential avoidance of coral snake banded patterns by free-ranging avian predators in Costa Rica". Evolution. 47: 227–235.
  10. ^ Brodie III, Edmund D., Moore, Allen J. (1995). "Experimental studies of coral snake mimicry: do snakes mimic millipedes?". Animal Behavior. 49: 534–6.{{cite journal}}: CS1 maint: multiple names: authors list (link)
  11. ^ Pfennig, David W., Harcombe, William R., Pfennig, Karin S. (2001). "Frequncy-dependent Batesian mimicry". Nature. 410: 323.{{cite journal}}: CS1 maint: multiple names: authors list (link)

Further reading

Media related to Calliophis at Wikimedia Commons Media related to Micrurus at Wikimedia Commons

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