The best way for an animal to camouflage itself and avoid getting eaten is to disguise itself as an inanimate object, scientists say.
According to a paper published on September 14 in the journal Proceedings of the Royal Society Bpretending to be a neutral object, like a leaf, twig, or rock, is a better tactic to avoid being spotted by predators than attempting to blend in with the background.
“A comparison between the types of camouflage had never been done,” João Vitor de Alcantara Viana at the State University of Campinas in Brazil, told New Scientist. “We thought it would be a great opportunity to understand how camouflage evolved and how the types of camouflage interact.”
Camouflage in animals can come in a variety of forms, ranging from visible to olfactory. Disruptive coloration breaks up the visual outline of the animal itself, like a zebra’s stripes or a leopard’s spots, while others change how they blend into the background as the conditions change, like chameleons or octopuses.
Eyespot camouflage can resemble a predator’s eyes, scaring off threats, while motion camouflage involves an animal moving in a certain way that they don’t appear to be moving to the other party. Transparency and countershading are often used by marine animals, and masquerade camouflage is used to resemble a neutral part of the surroundings.
The authors of the paper compiled data from 84 publications regarding animal camouflage and predator search time. They found that compared to undisguised animals, predators took four times longer to find animals performing this masquerade camouflage.
This technique is employed by stick insects, some species of spiders that resemble animal droppings, fish that are camouflaged to look like leaves on the bottom of a stream, and a variety of leaf insects, among many others.
Other camouflage methods, like blending into a backdrop or having chaotic color patterns, only increased predator search time by around 55 percent.
“Motion camouflage did not increase [predator search time] but decreased [predator attack rate] on prey. We found no evidence that eyespot increases [predator search time] and decreases [predator attack rate] by predators,” the authors wrote in the paper.
Animals may also use coloration as warning signals to predators. This aposematism instead makes themselves as bright and noticeable as possible to caution the predator from eating them. These animals are often poisonous, so the predator learns to associate this coloration with the horrible taste or sickness after eating that species, leading to it avoiding them in the future.
Some more advanced forms of camouflage include mimicry, which is when non-toxic species take advantage of a predator’s aversion to these bright colors. One example of this is found in the Viceroy butterfly, which has evolved to resemble the bitter-tasting Monarch butterfly.