Vipers are typically short and stocky in appearance, and are mainly land or tree dwelling, although some semi aquatic species do exist. Hairy bush vipers are slender with very long scales that curl up at the tips. It is pale to dark green or yellow in colour, and it may be possible to spot faint crossbars across the back. These snakes are small, growing to 2 feet, but have a deadly venom. They are native to the forests of West Africa.
Horned adders are another type of venomous viper.
They are short and stocky in appearance, with a flattened body and short tail. These snakes have a horn above each eye, and are generally coloured according to the soil on which they live, for camouflage purposes. Horned adders are also small, being little longer than a foot. They are found in the desert and semi-desert of south and south west Africa. Gaboon vipers are one of the larger types of vipers, growing up to 7 feet in length.