How does *Cerastes cerastes* produce an acoustic warning when threatened?

Answer

By rubbing together specially serrated scales on its sides

Since it cannot hiss through the nose, *C. cerastes* produces a rasping or crackling sound by rubbing specially serrated scales arranged in oblique rows on its sides as a primary defense warning.

How does *Cerastes cerastes* produce an acoustic warning when threatened?
animalreptilehornsnakeviper