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Coral snake

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Coral Snakes
Scientific classification
Kingdom:
Animalia
Phylum:
Chordata
Class:
Reptilia
Order:
Squamata
Suborder:
Serpentes
Family:
Elapidae
Genus:
Leptomicrurus
Micrurus
Micruroides
Species

Over 65, see article.

The coral snakes are a large group of elapid snakes that can be divided into two distinct groups, New World coral snakes and Old World coral snakes. There are three genera among New World coral snakes that consist of over 65 recognized species.

Coral snakes are most notable for their red, yellow/white, and black colored banding. Several nonvenomous species have similar coloration, however, including the Scarlet Kingsnake and the Milk Snake. In some regions, the order of the bands distinguishes between the non-venomous mimics and the venomous coral snakes, inspiring some folk rhymes — "Red and yellow, kill a fellow, red and black, venom lack". However, this only reliably applies to coral snakes in North America; Micrurus fulvius, Micrurus tener, and Micruroides euryxantus, found in the south and eastern United States. Coral snakes found in other parts of the world can have distinctly different patterns, and can even 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 24" in length, but specimens of up to 60" or slightly larger are not unheard of. South American species can get much larger. They are thin bodied snakes, with a head the same width as the body, small eyes, and a rounded snout. Aquatic species have flattened tails, to act as a fin, aiding in swimming.

Behavior

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

Like all elapid snakes, coral snakes use a pair of small fangs, which are fixed in the front of their top jaw, to deliver their venom. Due to the time it takes for the venom to take effect, 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 a single percent of the number of snake bites each year in the United States. Most coral snake bites occur because of accidental handling of the snake while engaged in an activity like gardening.

Photo of a coral snake in the park , showing typically reclusive behavior of hiding under rotting wood. Note the red and black bands separated by yellow. This one was well over 30 inches long, but slightly less than an inch across.

Venom

Due to the small size of coral snakes, along with their having much smaller fangs than pit vipers, bites are frequently ineffective and have some difficulty penetrating shoes or even thick clothing. This along with the fact that coral snakes are not aggressive creatures and reclusive makes bites quite rare. However, coral snakes are highly venomous, being the only relative of the cobra found in the New World. Despite their relatively small size, their venom is a powerful neurotoxin, quite capable of killing an adult human. No deaths related to coral snake bites have been reported in the United States since coral snake antivenin became available. Before that time, the estimated case fatality rate was 10%. Any bite from a coral snake should be considered life threatening and immediate treatment should be sought. Often there is very little reaction around the bite area, as opposed to the pain and swelling usually associated with a viper bite, and systemic effects can delay manifestation for 8-24 hours. This potential delay in symptoms makes treating coral snake bites particularly tricky, and often results in preventative treatment whether one is displaying symptoms or not. Once the neurotoxin takes effect, it causes the neurotransmitters between the brain and muscles to malfunction. Initially symptoms are slurred speech, double vision, difficulty swallowing, but can quickly progress to muscular paralysis, and even respiratory or cardiac failure if not treated.[1]

Wyeth manufactures a North American coral snake antivenom, also Instituto Bioclon manufactures an antivenom for coral snake species found in Mexico. A third type of antivenom is manufactured in Brazil to treat bites from some coral snake species found there. Unfortunately, no one antivenom is effective against all coral snake envenomations, and due to the relative rarity of bites from coral snakes and high cost of the antivenom, few hospitals stock it.

Taxonomy

Genus Leptomicrurus:

  • Leptomicrurus collaris collaris (Schlegel, 1837)
  • Leptomicrurus collaris breviventris (Roze & Bernal-Carlo, 1987)
  • Andes/Andean Blackback Coral Snake, Leptomicrurus narduccii
  • Leptomicrurus narduccii narduccii (Jan, 1863)
  • Leptomicrurus narduccii melanotus (Peters, 1881)

Genus Micruroides:

  • Micruroides euryxanthus australis (Zweifel & Norris, 1955)
  • Micruroides euryxanthus euryxanthus (Kennicott, 1860)
  • Micruroides euryxanthus neglectus (Roze, 1967)

Genus Micrurus:

Texas Coral Snake, Micrurus tener

Mimicry

New World coral snakes are known to mimic False coral snakes, snake species which are less poisonous. This is a rare example of Mertensian mimicry. Species of false coral snake include:

References

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