Texas coral otter
| Texas coral otter | ||||||||||||
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Texas coral otter ( Micrurus tener ) |
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| Micrurus tener | ||||||||||||
| Baird & Girard , 1853 |
The Texas coral otter ( Micrurus tener ) is a poisonous snake (Elapidae) and belongs to the genus of the coral otter ( Micrurus ). The species was first described in 1853 by herpetologists Charles F. Girard and Spencer F. Baird.
features
Micrurus tener usually reaches a length of 61 to 91 cm. The collector Don Mascarelli documented a 118.1 cm specimen in Colorado County . The species has a black-colored, blunt head, which hardly separates from the neck and has a yellow ring behind the eyes. The eyes are black and have a round pupil. The rein shield ( Scutum loreale ) is missing. The body is extremely slim. Narrow, sulfur-yellow and wide red and black rings stretch across the body, with the red rings scattered with black spots. A black collar extends to the rear tips of the parietal shields ( Scutum parietale ). Starting with this collar, the pattern proceeds in the order black-yellow-red-yellow, then starting again with black. The drawing continues on the ventral side. 15 rows of scales run over the back ( scutum dorsale ). The scales below the tail ( scutum subcaudale ) are arranged in a double row and the anal shield ( scutum anale ) is divided.
Snake venom
As a poisonous snake, the Texas coral otter has fixed poisonous teeth in its front upper jaw (proteroglyphic tooth position). It produces a highly potent snake venom ; the mean lethal dose , measured on laboratory mice, is 0.8 mg per kg of body weight. Above all, the toxin has neurotoxic properties; alpha neurotoxins prevent the transmission of signals to the muscle fibers at the motor endplate by binding competitively to the postsynaptic acetylcholine receptors. However, it also contains proteins that have an effect on hemostasis (blood clotting). Both procoagulative thrombin-like and plasmin- inhibiting, as well as anticoagulative fibrinolytic and factor Xa-inhibiting activity can be demonstrated. It is conceivable that in the future medically usable active ingredients could be obtained from the poison of Micrurus tener . The toxin also contains phospholipase A₂ .
As a result of a bite accident, paralysis occurs, death can result from respiratory paralysis or heart failure. Antivenins (antidotes) have been available since 1967 ; fatal bites with Micrurus tener have not been recorded in the USA since then. Previously, the mortality was 10%. Coralmyn® is an important polyvalent antivenin. It is a polyclonal antivenin, consists of a (Fab) 2 fragment and is obtained by immunizing horses using the toxin from Micrurus nigrocinctus nigrocinctus . It has been shown to be well effective against the Micrurus tener toxin .
Way of life
The species leads a hidden way of life and mostly hides in the ground or hides under tree stumps and the like. It reproduces through oviparity , so it is egg-laying. The young snakes measure between 16.5 and 23.9 cm when they hatch. The eggs will probably be buried in loose soil. The Texas coral viper feeds primarily on smaller, burrowing snakes .
distribution
The distribution area extends in the south of the USA from western Louisiana and southwestern Arkansas west to central (and partly western) Texas and south to the Mexican states of Coahuila , Nuevo León , Tamaulipas , Veracruz , Hidalgo , Guanajuato and San Luis Potosi . No specific altitude levels are inhabited, in the USA the species penetrates up to approx. 500 m in height, in Mexico up to over 2000 m in height. The Texas coral otter is not endangered and its population is considered stable.
habitat
Micrurus tener is not tied to a specific habitat, but seeks biotopes with fertile soil within its range. For example, the mixed and pine forests of East Texas and the prairie and deciduous forests of North and Central Texas as well as the remnants of subtropical forests near Brownsville are inhabited. In the counties of Pecos and Terrell , the species can be found in more or less arid areas, where it mostly seeks out isolated trees in damp ravines. Texas coral otters are occasionally found in and around large cities, visiting vacant spaces within human settlement areas. However, the population density of the snake is decreasing within the metropolitan areas.
Systematics
The Texas coral otter was until recently assigned as a subspecies under the name Micrurus fulvius tener of the harlequin coral otter . As a result of studies by Crother et al. (2000), Collins & Taggart (2002) and Campbell & Lamar (2004) it received species status.
Subspecies
The Reptile Database lists 4 subspecies:
- Micrurus tener fitzingeri ( Jan , 1858)
- Micrurus tener maculatus Roze , 1967
- Micrurus tener microgalbineus Brown & Smith , 1942
- Micrurus tener tener ( Baird & Girard , 1853)
Individual evidence
- ↑ a b c d e IUCN Red List: Micrurus tener
- ↑ a b c d EE Sánchez, JC Lopez-Johnston, A Rodríguez-Acosta, JC Pérez: Neutralization of two North American coral snake venoms with United States and Mexican antivenoms . In: Toxicon 51, 2008, pp. 297-303. PMID 18054059
- ↑ a b A. M. Salazar, J. Vivas, EE Sánchez, A. Rodríguez-Acosta, C. Ibarra, A. Gil, Z. Carvajal, ME Girón, A. Estrella, LF Navarrete, B. Guerrero: Hemostatic and toxinological diversities in venom of Micrurus tener tener, Micrurus fulvius fulvius and Micrurus isozonus coral snakes. In: Toxicon: official journal of the International Society on Toxinology. Volume 58, number 1, July 2011, pp. 35-45, doi : 10.1016 / j.toxicon.2011.04.020 , PMID 21596052 , PMC 3304457 (free full text).
- ↑ facmed.unam.mx: Coralmyn®
- ↑ Micrurus tener in The Reptile Database ; Retrieved September 4, 2011.
Literature and Sources
- Dixon & Werler: Texas Snakes - A Field Guide , Texas Natural History Guides, University of Texas Press, 2005. ISBN 978-0-292-70675-0 .
- Conant & Collins: Reptiles and Amphibians - Eastern / Central North America , Peterson Field Guides, 1998. ISBN 978-0-395-90452-7 .
