New research published in the journal Animal Behaviour has uncovered the genius of European vipers' zigzag pattern, revealing that it serves three defensive functions when the snake is under attack. In breaking up the animal’s silhouette the zigzag first serves as a means of camouflage but once detected, it can both ward off and confuse the predator as the snake slips away.
Led by scientists from the University of Jyväskylä, the research reveals how even single-color patterns can be multifaceted in enabling those that sport them to entrap or evade other animals. Protective coloration is a very common means of predator evasion but most animals that exhibit the defense strategy use different colorations for different purposes.
Some use theirs as means of obscuring themselves, such as chameleons, which blend into their environment, others are aposematic, which protects the animal by making them look menacing, such as wasps. Another strategy is to produce an optical illusion that can confuse or scare predators just long enough to get away. But a series of experiments undertaken by Janne Valkonen and Johanna Mappes at the University of Jyväskylä, Finland, has found that European vipers (Vipera sp.) can achieve all three tricks with a single-color pattern – their characteristic zigzag.
They first tested the zigzags' benefit for hiding using plasticine models of snakes with differing color patterns dotted them along a path before challenging volunteers to walk to the trail and report back how many “snakes” they saw. The reports revealed far more plain-colored snakes being spotted than those with the zigzag pattern. Previous research has established that the vipers’ zigzag pattern serves as an aposematic warning of their fierce bite, so all that was left to tick off was if the color pattern acted as an optical illusion.
The most significant finding was the discovery of a particular class of illusion created by the vipers’ zigzag. In the same way that flick-book cartoons can create a moving image, when rapidly flickered, the zigzags also create a solid, moving shape. The team measured the speeds of fleeing vipers and used recorded footage to calculate the flick rate of the zigzag. They found that the zigzag moved fast enough to create a “flicker-fusion effect” to the eyes of mammalian predators, changing the appearance of the moving snake and making it more difficult to catch. This effect however wasn’t effective in the eyes of raptors, which have exceptionally fast vision.
While the viper’s zigzag monochrome pattern might seem a plain one, it is in fact a masterful illusion that can enable the snake to hide, spook, and scarper all in one. The discovery expands the discussion on protective coloration and anti-predator adaptations in demonstrating how a single-color pattern can have multiple effects during a predation event.