A puff adder lies in wait, camouflaged by its natural habitat-matching coloration and commitment to stillness. Photo by Wits University
JOHANNESBURG, South Africa, Jan. 11 (UPI) -- New research suggests the African puff adder has two main stealth strategies. Researchers already knew about the first, extreme patience and stillness, but a new study has revealed a second -- chemical camouflage. The snake has evolved to suppress its scent.
The puff adder is the deadliest snake in Africa, responsible for some 30,000 deaths per year. The viper's ubiquity throughout the continent and its highly toxic venom are the main reason for this, but its ability to hide is also at play.
Recently, researchers at the University of the Witwatersrand in Johannesburg, South Africa, set out to investigate the snake's elusiveness. Puff adders are committed to visual camouflage. They will lie in wait for as long as two weeks, motionless -- typically beneath thin grass cover, overgrowth or brush.
Scientists wondered why such an approach didn't make the snake vulnerable to attack.
The reason was smell. Scientists found the snakes are also extremely hard to detect by scent. Researchers from Witwatersrand observed the viper's primary predators -- including wild dogs and meerkats, a type of African mongoose -- walking right over the snakes without noticing their presence.
Scientists followed up their field observations with lab tests.
"We asked the meerkats and dogs to scent-match scent samples collected from puff adders and other snake species," lead researcher Ashadee Kay Miller, a Wits post-graduate student, explained in a news release. "The scents of most snakes were easily identified by the dogs and meerkats, but they failed dismally when it came to puff adder scent."
The ability to suppress its scent is called chemical crypsis, and researchers say the viper is the first terrestrial vertebrate species to exhibit the quality. But Miller and her colleagues suspect other ambush predators can hide their smell, too.
The new research was published in the journal Proceedings of the Royal Society B.