Head to head
Horned Viper vs Sidewinder
A horned viper and a sidewinder live on entirely different continents and belong to different genera, yet both move across loose desert sand using the exact same distinctive sideways locomotion, one of the clearest examples of convergent evolution among snakes.
| Horned Viper | Sidewinder | |
|---|---|---|
| Native range | Sahara Desert, North Africa, Middle East | Southwestern US, northern Mexico |
| Genus | Cerastes | Crotalus |
| Movement style | Sidewinding | Sidewinding |
| Eye horns | Present in most individuals | Small raised scales above each eye |
| Venom delivery | Venomous viper | Venomous rattlesnake |
| Rattle | No true rattle, rasps scales instead | True rattle at tail tip |
| Hunting style | Buried ambush | Buried ambush |
| Evolutionary relationship | Unrelated to sidewinder | Unrelated to horned viper |
Horned Viper vs Sidewinder: common questions
Are the horned viper and the sidewinder related to each other?
No, despite moving in the same distinctive sideways manner and sharing small horn-like scales above the eyes, the two species belong to entirely different snake genera on different continents, with the horned viper in the genus Cerastes found across the Sahara and the sidewinder in the genus Crotalus, the rattlesnakes, found in North American deserts. Their shared traits are the result of convergent evolution, in which two unrelated species independently arrived at very similar physical solutions to the shared challenge of living and hunting in loose desert sand.
Why did two unrelated snakes both evolve the same sidewinding movement?
Sidewinding minimises the amount of a snake’s body in continuous sliding contact with loose, shifting sand at any given moment, which dramatically reduces the slippage that would otherwise make normal forward-undulating movement inefficient or exhausting on fine desert sand. Because both the horned viper and the sidewinder independently evolved to live in very similar loose-sand desert environments on different continents, natural selection favoured the same effective solution in both lineages separately, rather than either species inheriting the trait from a shared ancestor.
Does the sidewinder have a rattle but the horned viper does not?
Yes, the sidewinder is a true rattlesnake and possesses the segmented rattle structure at the tip of its tail that is characteristic of the genus Crotalus, used to produce its well-known warning buzz. The horned viper lacks any true rattle structure entirely, and instead produces a rasping, hissing warning sound by rubbing coils of its rough, keeled body scales together, a different mechanism that happens to produce a broadly similar warning function despite the two species having no close evolutionary relationship.