Happy Halloween! Children all over are dressing up in their costumes to head out trick-or-treating. But these children, disguised as spooky vampires or Wonder Woman, aren’t the only ones with a few tricks up their sleeve. Animals can use disguises too! Some animals have actually developed physical or behavioral characteristics that copy other species or objects, a strategy called mimicry. Using appearances, sounds, smells, or behaviors, mimicry provides an animal with some advantage, usually protection from predators. But unlike kids throwing on a costume for a day, the mimic’s display isn’t a conscious choice by the animal; rather it is the product of millions of years of natural selection. Because the mimicry helps the animal survive in some way, those characteristics are more likely to be passed on to the next generation.
There are many types of mimicry. Batesian mimicry, named after the English naturalist Henry Walter Bates, is one of the most common forms and occurs when a tasty or vulnerable creature mimics an unsavory or dangerous creature. Below are several examples of Batesian mimicry that can be found right in your backyard!
Hoverflies are excellent mimics, warding off predators with their coloration. These small flies are harmless, but with their black and yellow stripes they look like stinging bees and wasps. They can often be seen hovering at flowers, feeding on nectar and pollen. Can you tell which two photos are of hoverflies and which two are not?
Here’s another example of mimicry through colors and patterns. “Eyespots” may mimic the eyes of a larger animal and serve to scare away potential predators, especially young birds. Eyespots can frequently be found on the wings of butterflies and moths, as well as on caterpillars.
These two species of caterpillars have clear eyespots near the front of their bodies. These body markings could help the caterpillar mimic the look of a snake or other more threatening predator. The actual eyes are located on the head, which is the smaller bump at the base of the large pseudo-head.
Another deception – the eastern tiger swallowtail caterpillar mimics the appearance of bird poop in its early stages, which reduces the likelihood of getting eaten by birds or other insects.
A second type of mimicry is called Müllerian mimicry, named after the German naturalist Fritz Müller, in which several species that are equally harmful or unsavory have evolved with shared characteristics. Predators quickly learn to avoid that characteristic, which then benefits all the mimicking species. One example of this is the monarch and viceroy butterfly. Scientists have determined that birds tend to dislike the taste of both butterflies. By sharing a similar color and pattern, these butterflies are advertising that they are not tasty and birds are more likely to avoid both species.
Viceroys and monarchs can be difficult to tell apart. If you look at the lower wing of the butterfly, viceroys have a bold black line that monarchs do not have. Also, viceroys are usually smaller than monarchs.
Mimicry is not only used by animals, but plants and fungi use it as a survival strategy too. There are orchids that have evolved to resemble female insects, so that male insects will be attracted to the fake mate and will collect and/or deposit pollen when they land on the flower. There are fungi that mimic the smell of rotting meat to attract insects, which then help spread the fungi’s spores. There are plants that very precisely mimic the chemical signals released by insects during mating season, which attracts more potential pollinators to the plant.
Mimicry plays a very important role in the survival of many species. It is a complex system involving plants and animals, predators and prey alike, each trying to deceive for safety, food, or propagation. So this Halloween, when kids are in full disguise, think about all the plants and animals that have precisely developed costumes too. If some prey can’t come up with a good trick, the predator may be in for a treat!
Post by Kelsey Ruffino, Student Conservation Association and State Parks
Featured image: praying mantis by Lilly Schelling, State Parks