Batesian Mimicry: How Imitators Defend Themselves

Imagine for a second you're not very strong—actually, you're pretty weak, with no real defenses. While this might be fine if you're lounging on your couch reading this on your phone, now imagine you're in middle school. The only major downside to being weak in that scenario is getting bullied. For many animals and plants, getting bullied means getting eaten, and that's something animals are trying to avoid daily.

However, there are ways to avoid this fate. For example, you could invest heavily in becoming highly toxic, having an excruciating sting, or tasting awful—basically, any unpleasant consequence for a predator trying to capture you. But that's not the only route; you could also evolve over generations to simply look like something that is toxic, stinging, or foul-tasting.

Mimicry occurs when two different species, a model and a mimic, evolve to resemble each other. This phenomenon is advantageous to the mimic, as it often gains a survival edge over species that don't mimic. Over time, mimics begin to more closely resemble their models. In cases where the mimic is harmless but the model is dangerous or harmful, this is known as Batesian mimicry, and it provides the mimic with protection from predators, as seen in many organisms.

Copying Predators

"Batesian mimics are undefended species that mimic a defended model, gaining protection through their resemblance to the harmful model," says Susan Finkbeiner, an entomologist and ecologist from the Department of Biological Sciences at California State University, Long Beach. "The variety of insects that resemble wasps and bees has always intrigued me. There are moths and flies that look like bees, and harmless grasshoppers and beetles that resemble wasps. Their resemblance is so precise, even down to the smallest details!"

Batesian mimicry was initially described in non-predatory animals, and it's common in species like frogs, snakes, and butterflies. However, plants and fungi also engage in mimicry to avoid predators: Some plants mimic rocks to avoid herbivores, and certain fungi imitate parts of flowers to attract pollinators, ensuring their spores are spread along with pollen as the pollinators travel from one flower to another.

Finkbeiner explains that Batesian mimicry only works under specific conditions. For one, looking dangerous, toxic, or unpleasant only benefits the mimic if predators have already learned to avoid such traits. Additionally, the mimic must share the same geographic area as the model species—otherwise, predators won't have learned to avoid the mimic. Finally, there must be more models than mimics in the area, or predators might begin to recognize that some mimics are harmless.

While Batesian mimics typically only resemble their model species, some take this mimicry to the next level by imitating the behaviors of their models as well—such as replicating sounds, flight patterns, and antennal movements.

Other Types of Mimicry

Certain organisms mimic things entirely different from their own species, such as katydids and moths impersonating leaves, or caterpillars and stick insects imitating twigs.

"Instead of classifying this as Batesian mimicry, it's more accurately referred to as 'masquerade,' where an organism pretends to be something it's not," explains Finkbeiner. "When masquerade combines with Batesian mimicry, it's termed 'protective deceptive mimicry.'"

In Müllerian mimicry, two unrelated harmful species share similar appearances to enhance the warning signals they send to predators—basically saying, 'Don't touch, danger ahead.'