Masters of Disguise

Caterpillars are faced with a tremendous task as their only goal is to nourish themselves to the point where they can fully develop as a butterfly or moth. As caterpillars find food to sustain themselves as they are growing, they are at a disadvantage in terms of defense. The sizes and speeds that caterpillars travel at make them susceptible to being targeted by small birds and other predators as prey. Because of this, caterpillars begin to adapt unique changes to their appearance to perfect their camouflage tactics to keep predators away from them.

The caterpillar of the Elephant Hawk Moth (Deilephila elpenor) can defend against predators by assuming a snake-like appearance that is threatening to predators to every kind. When threatened, these caterpillars retract and show their bulging heads that give the illusion that they are snake-like and possibly dangerous showcasing two ‘eye-like’ markings that make it appear much larger. When caterpillars develop and get closer to becoming moths or butterflies, their body structures change in a way that makes them more appealing to predators as they increase in fat. Their slow-moving characteristics, nutritional benefits (to other animals) and abundance makes caterpillars an ‘easy prey’ so caterpillars take advantage of their “disguises” during this phase of their lives. Most caterpillars have a unique way of protecting themselves from predators, what contributes to these characteristics?

Caterpillars’ adaptive nature to these ‘disguises’ reflects Charles Darwin’s natural selection theory proposing that only the ‘fittest’ or the organisms most successfully adaptive to whatever environment they are in will survive. Specifically, the Deilephila elpenor have evolved eyespots on their bodies (that show as they are caterpillars or fully grown) and use mimicry of snake-like features to make it more conspicuous. Risk avoidance behavior develops in predators where instead of ‘taking the risk’ to find out whether the caterpillars are dangerous, they make the notion to stay away so they may increase their chances of survival. Evolution and natural selection play a role in creating mimicking organisms, but genes are the most prominent physical mechanism of mimicry. Some organisms have physiological control over their mimicking characteristics, but the structures of mimicry are most often genetic characteristics.

The type of mimicry these caterpillars display is referred to as Batesian mimicry in which the caterpillars assume the appearance of something that could be potential to predators, causing them to stay away. Currently, we are learning about heredity and how genes are passed through meiosis. Traits that are passed down usually provide some benefit to an organism to help them survive longer, which again reflects natural selection. Batesian mimicry is often looked at in phylogenetic charts that display evolutionary relationships based on similarities (or differences) in genetic characteristics. This analysis helps to study how various types of mimicry are passed through generations and is essential in figuring out what facilitates evolution of other mimicry features. Considering the eye-spot mimicry that occurs in these caterpillars, these traits usually result from some random gene variations in nature and if these traits begin to increase survival of these caterpillars, they can sustain and pass on these traits to future generations. In this way caterpillars finish the cycle of metamorphosis whilst pulling off the greatest scam of the century, fooling predators left and right and increasing their population.

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Biology Teacher

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