Viperidae family

Very venomous snakes, that characterize themselves to have movable face bones; ectopterigoide (transpalatino) extended to the jaw; supratemporary present. Very short, perpendicularly eréctil Maxilar to the ectopterigoide and supporting a pair of curved, hollow and inoculadores eyeteeth of venon, but without external furrow. Hipapófisis developed throughout the spine.

This Family includes snakes in her majority ovovivíparas and of diverse habits. There are more than 80 species, distributed by America, Europe, Asia and Africa.

The snakes viperidaes of the American continent are grouped in a subfamily: CROTALINAE, and are characterized to externally have the bones maxilares excarvados and had by fosetas loreales thermorreceptors. In Venezuela, the called snakes belong to this family "mapanares" , "cuatro narices" , "cascabeles" and "cuaimas" , with a total of 20 species and subspecies, located in the sorts: Bothriechis, Bothriopsis, Bothrops, Crotalus, Lachesis and Porthidium.

The evolution of the snakes of the Viperidae family in the American continent, leaves from the groups Trimesurus-Bothrops and Agkistrodón of the old continent. In the Paleoceno these species arrive at the new world through Straits of Bering, where Bothrops follows the line familiar and Agkistrodon gives rise to two new familiar branches, Lachesis and Crotalus. In Venezuela they represent the more important venomous snakes of the country.

They have common characteristics by which it is possible to be recognized to them like family, like, eyes with vertical pupils for being of habits nocturnes. Outstanding head either of the body with form triangular or heart form to own venomous or developed glands in the lateral part of the head.

Between the eye and thermorreceptors the nasal grave it presents/displays fosets or loreal, composed by an orifice closed internal by a membrane rich inervada, very radiation sensitive infrared emitted by the heat of the bodies of the animal. This means of heat detection are so sensible that it can hardly discriminate a variation of temperature of 0,6ºC in relation to the surrounding atmosphere, which allows him to locate and to hunt to the prey with high accuracy in the dark.

Its set of teeth is solenogliph, presenting/displaying in maxilar two long eyeteeth crossed by a channel which inject venon. When they get ready to attack they twist in the form of spiral with the head raised in typical defensive attitude. Robust body that tends to be heavy with diameter of until 10cm, Which does of these heavy serpents animal of slow displacement, around 2 to 3 km/h of speed (the fast step of a man is from 5 to 6 km/h).

References:

Campbell, J. A. and W. W. Lamar. 2004. The Venomous Reptiles of the Western Hemisphere. Cornell University Press. 1032 pp.

Greene Harry W., 1997. Snakes The Evolution of Mystery in Nature. University of California Press 351 pp.

Kornacker, P. M. 1999. Checklist and key to the snakes of Venezuela / Lista sistemática y clave para las serpientes de Venezuela. PaKo-Verlag. 270 pp.

Lancini, A. R. 1979. Serpientes de Venezuela. Armitano Editores. 262 pp.

Lancini, A. R. y P.M. Kornacker. 1989. Die Schlagen von Venezuela. Armitano Editores. 381 pp.

La Marca, E. y P.J. Soriano. 2004. Reptiles de Los Andes de Venezuela. Fundación Polar, Conservación Internacional, CODEPRE-ULA, Fundacite Mérida, BIOGEOS. Mérida, Venezuela. 163 pp.

Navarrete, L. F., J. C. Lopéz Johnston y A. Blanco Dávila. (s/f) 2006. Guia de las Serpientes de Venezuela Biología, venenos, conservación y checklist. Graficas Lauki. 75 pp.

Roze J. A. 1966. La taxonomía y zoogeografía de los ofidios de Venezuela. Ediciones de la Biblioteca UCV. 362 pp.

Roze J. A. 1970. Ciencia y Fantasía sobre las Serpientes de Venezuela. Editorial Fondo de Cultura Científica, S.R.L., 160 pp.