The Art and Science of Blending In
Evolutionary Roots of Mimicry and CamouflagePosted on: November 4th, 2020
Sheltering-in-Place Blog Entry #30
A wildlife photographer dons her fall-themed camouflage suit before venturing into a western forest. She wears a hat with a patterned net that covers her face and protects her against insects. Even her camera and long telephoto lens sport camo tape. It is deer hunting season (early August to mid-November), so the photographer wears an incongruous bright orange vest, which seems to defy the logic of wearing leaf-patterned clothing to blend in with the environment. Hunters wear the same type of clothing, including the orange vest. This logic rests on the erroneous but wide-spread simplification that deer see in black and white or are colorblind. In fact, deer have fewer “cones” in their eyes and far more “rods,” allowing them to see much fewer colors (the role of the cones) but see much better in low-light conditions (role of the rods). This trait is essential precisely when hunters (and photographers) may be moving about looking for deer. Deer don’t see colors as we do, but they do see some. They are essentially colorblind to the red-green spectrum, just like people with Daltonism. Deer see well in the blue-green range of colors but can’t quite distinguish green from red or orange from red. Instead, those colors look gray. So, wearing a bright orange vest doesn’t clash with the other grayish colors the deer may be seeing. Nocturnal bird predators like owls are also essentially colorblind in various degrees, as are some bats, rodents, and raccoons. They have traded color vision for the ability to see better in the dark, which brings us to camouflage and mimicry.
Camouflage, or the ability to blend into your environment or background, and mimicry, the ability to look like something else in your environment, are advantageous traits in those species (prey) that are chased or consumed by other species (predators). They are also instrumental for predators who need to blend in with their surroundings when they are stalking prey (for example, a lion or a leopard hidden in the dry, tall grass, or a tiger, leopard, or jaguar slinking silently and well camouflaged through the mottled shadows of a tropical forest). A little Western Screech Owl (Megascops kennicottii, family Strigidae) can be both predator and prey, so blending well with its surroundings is critical to its success as a species.
Camouflage and mimicry are two of three distinct but equally efficient ways to fool an enemy or your next potential meal. The other one, disguise, is a variation on the theme, where animals use pieces of the background or nature as a disguise. Camouflage and mimicry are possible because of physical traits that the animals are born with or develop through life. These traits act as survival mechanisms in an explosively diverse world. Blending into the background is a way to protect oneself and avoid the attention of potential predators (“protective camouflage). And if you are a predator, you use “aggressive camouflage” where you blend in to increase your chances of catching your prey unaware.
Camouflage and mimicry are not just the look, the outline, and the colors and shapes that help the animal blend in with its environment. They also involve behaviors, such as standing perfectly still for long periods or swaying slightly, mimicking the movements of leaves, grasses, or shadows to perfection. Western Screech Owls are masters of blending in. When they close their large, yellow eyes (as when sleeping) can be practically invisible to larger diurnal predators, such as hawks.
Camouflage and mimicry are such successful evolutionary strategies that have appeared a near-infinite amount of times in all kinds of animals. Insects, in particular, demonstrate an extraordinary variety of strategies, some of which can simply verge on the unbelievable. For example, the leafy sea dragon (a fancy and adventurous name for a group of species of large seahorses) grow over their lifetimes an incredible set of “leaves,” which uncannily resemble a branch of marine algae. But perhaps the most intriguing and spectacular example of camouflage and mimicry is the tropical moss mimic walking stick, Trychopeplus sp., (probably T. laciniatus, Phasmatodea, of the family Diapheromeridae).
The order Phasmatodea or “ghost insects,” include a large number of species that resemble sticks, leaves, and mosses, making them one of the superstars of blending in. I can try to describe the absolutely stunning features of Trichopeplus, but a picture is better than a thousand words. Sitting silently, swaying gently within a patch of vines and vegetation, the moss sprig you see in this photo is an insect, blending so well with its surroundings that if it hadn’t moved when everything else was still, I would not have seen it. If you are having trouble seeing its parts, you are not alone, so let’s walk through it, starting from the upper right and down. The front legs are very long and have “leaflets, which point to the sides. The head is that bit with the downward-pointing brownish leaflet. You can barely see its green eye there. Then, the body…oh well, we might as well map it out and label the parts.
I love sharing these stories because they are not only marvels of nature, but because they expand our understanding of nature’s processes of evolution, predation, animal and plant defenses, and survival. They also ignite my desire to know more, explore, care, and protect these creatures and their habitats, and to continue to learn from them and make better decisions about how to manage and protect the habitats that sustain these species.
The future well-being of humanity rests on preserving the natural wonders that have catalyzed and permitted the development of today’s civilizations. Without nature, we would not have medicines, foods, materials, and soils to support our lives. These creatures that we so much admire and enjoy make their home in endangered and threatened ecosystems, vulnerable because of our disconnect with the essential roles they play in the balance of nature. When we share stories about such species, we move one step closer to protecting what’s left of nature in California and the world.
Carlos de la Rosa
FURTHER READING AND VIEWING