Micrurus tener, commonly known as the Texas coral snake, is a species of venomous snake in the family Elapidae. The species is native to the southern United States and adjacent northeastern and central Mexico. Five subspecies are recognized as being valid, including the nominotypical subspecies, Micrurus tener tener, which is found in both the US and Mexico, and is also commonly known as the Texas coral snake. The species Micrurus tener was once considered to be a subspecies of the eastern coral snake (Micrurus fulvius).
Geographic range
M. tener ranges from the southern United States south to northeastern and central Mexico. It inhabits the states of Texas, Louisiana and Arkansas, and the Mexican states of Tamaulipas, San Luis Potosí, Guanajuato, Querétaro and Morelos.
Description
The Texas coral snake has the traditional coloration associated with coral snakes: black, yellow, and red rings. These rings extend onto their belly. It is capable of growing to 48 in (122 cm) in total length (including tail), but most are closer to . Males are typically smaller than females. It has smooth dorsal scales, a rounded head, and the eyes have round pupils. Albinistic (lacking black pigment) and anerythristic (lacking red pigment) specimens have been found in the wild. "Pastel" (pink, translucent cream, and very light blue) coloration has been noted, and completely black (melanistic) specimens, are known. The Texas coral snake is somewhat larger (longer and stouter) than the eastern coral snake (Micrurus fulvius), and has a somewhat larger venom yield.
Behavior
All coral snakes are shy, secretive animals, typically nocturnal. They spend most of their time hiding in leaf litter, under logs. They can be seen crawling on the surface, after heavy rains, when the nighttime temperatures rise above .
When grabbed suddenly, or sometimes just when touched, they may thrash about, swing around, and bite. Sometimes they are calm, and then suddenly swing around and bite, for no apparent reason.
Diet
The primary diet of M. tener consists of other snakes, primarily earth snakes, and other small fossorial species. It is cannibalistic. It also occasionally eats small lizards, but the consumption of rodents by coral snakes is rare.
Reproduction
M. tener is oviparous.
Mimicry
Other nonvenomous snakes resemble the Texas coral snake as a form of Batesian mimicry. In the United States only, all three species of venomous coral snakes (Micruroides euryxanthus, Micrurus fulvius, and Micrurus tener) can be identified by the red rings contacting the yellow rings. A common mnemonic device is "red and yellow, kill a fellow. Red on black, friend of Jack". However, this mnemonic is not always accurate, due to the aforementioned color variations, and its usage is dangerous to both snakes and humans.
Venom
Texas coral snake venom is a powerful neurotoxin, causing neuromuscular dysfunction. Until 2006, no deaths from coral snake bites had been reported since the 1970s in the United States; however, rare, fatal bites have occurred, according to several scientific journals in the 1980s and 1990s.
Because of the low profits, the production of coral snake antivenin has been discontinued for several years. Prior to the availability of antivenin, the fatality rate of coral snake envenomations has been estimated at 10%, and death was primarily due to respiratory or cardiovascular failure as a result of paralysis induced by the neurotoxic venom.
Wyeth Pharmaceuticals, a wholly owned subsidiary of Pfizer, produced antivenin for the eastern coral snake, which can also be used for treatment of envenomation by the Texas coral snake. However, the last lot produced (Lot L67530) has an expiration date of January 31, 2020. Pfizer indicates that antivenom is available and one source states that production has resumed.