The Puff Adder (Bitis arietans) a highly venomous snake that together with the Mozambique Spitting, Cobra accounts for the majority of serious snake bites in Southern Africa. As the common name suggests, when threatened the Puff Adder will begin hissing and puffing by rapidly inhaling and exhaling air serving as an early warning system not to mess with it. | African Snakebite Institute

Why do we call this snake a puff adder? Well looking at this video you can see that it is a very appropriate name for this snake. The puff adder will inhale and exhale air through its nostrils and this causes the sound that tells you, Watch out! | African Reptiles and Venom