Vipers: Venomous
This family includes some of the most recent
and advanced snakes on earth. Vipers have longer fangs, proportionally, than
other venomous snakes. In addition, the fangs of vipers are hinged, and close
close to the roof of the mouth when the mouth is closed. Alternatively, when
striking, the fangs are erected and are directed a considerable degree forward.
The mole vipers (genus Atractaspis) have fangs that are so long that they
cannot be handled safely without implements.
Viper venom is predominantly
haemotoxic,
destroying blood cells and their vessels. Some species, most notably some South
American vipers and the American rattlesnake Crotalus scutellatus, have
neurotoxic (nerve destroying) elements in the venom. Worldwide, vipers account
for far more human snake-bite fatalities than other snakes, with the major
killers being Russell's and saw-scaled vipers.
There are two broad divisions, or subfamilies,
of vipers. The Viperinae contains most of the Old World vipers. The Crotalinae
is the pit vipers, snakes with a heat-sensitive pit between the eye and nostril.
Pit vipers are distributed throughout the New World and Asia. There are no
vipers in Australia, Madagascar, New Zealand, or most islands in Oceania.
