Vipers are a family of venomous snakes found in most parts of the world, except for Antarctica, Australia, Hawaii, Madagascar, New Zealand, and various other isolated islands. They are characterized by their long, hinged fangs that permit deep penetration and injection of their venom. Vipers have vertically elliptical or slit-shaped pupils that can open wide to cover most of the eye or close almost completely, which helps them to see in a wide range of light levels. They are nocturnal and ambush their prey.

Vipers are divided into two groups: pit vipers and Old World vipers. Pit vipers have a temperature-sensitive pit organ located on each side of the head midway between each nostril and eye, which enables them to “see” heat images of warm-blooded prey. Old World vipers live in desert to forest habitats of Europe, Asia, and Africa and are typically slow, stocky, and broad-headed.

Some interesting facts about vipers include:

• Vipers are venomous, and all species have long, hinged fangs.
• There are more than 200 species of viper.
• Vipers range in length from less than 25 cm (10 inches) to more than 3 meters (10 feet) .
• Vipers are known for their extreme fangs, which are long, hollow, hinged, and rotatable.
• Generally, more venomous vipers are found in tropical areas, particularly South America and Africa.
• Vipers found in colder, northern climates, such as the black or European adder, have more moderate venom.

In summary, vipers are a family of venomous snakes found in most parts of the world, except for certain isolated islands. They are characterized by their long, hinged fangs and are divided into two groups: pit vipers and Old World vipers.