I have always thought it was interesting how caterpillars have the ability to pretty much change into a completely different animal during their life. To be honest it doesn’t really make much sense to me because for half of their life they are able to move about a foot every twenty minutes, and then the other half they have wings and can fly. But my big question is if they remember the time before they could fly.
According to Nancy Miorelli, an entomologist, caterpillars don’t know that they are eventually going to turn into butterflies. She compares it to humans going through puberty; we have no control over the hair that grows on our body during that time. Just like us, hormones signal the body to start growing, but it’s not until the juvenile hormone is no longer present that they transform into the cocoon (1).
Scientists’ previous understanding of what occurred inside of cocoons was that the caterpillar turns to complete mush before it reforms into a butterfly. But just like we have heard in class many times, scientists can be wrong. It is true that most of the insect dissolves, however most of the vital organs stay pretty much intact with some minor alterations in order to be more effective in the new body. For example, the tracheal tubes grow larger because the butterfly is going to need a greater amount of oxygen because it is exerting more energy flying.
The brain is a different situation. The brains of insects contain many different segments. One particular segment is in charge of smelling, taste, learning and memory. Miorelli explains that these factors are vital to the organism’s survival throughout its entire lifespan that they are unchanged during the transformation. The remainder of the brain becomes new and improved for the insects new and improved body.
From Miorelli’s statement about memory remaining intact through both the life of the caterpillar and butterfly, we can assume that my question about butterflies remembering being caterpillars right?! There was a randomized control trial performed by the University of Edinburgh in the U.K. in order to prove exactly that. Manduca sexta caterpillars were electrically shocked in combination with a distinct smell to train their distaste for that specific aroma (2). The null hypothesis in this experiment was that the caterpillars would not be able to remember their aversion to the smell post metamorphosis. The alternative hypothesis was that the caterpillars would remember their aversion to the smell post metamorphosis. Interestingly enough, their distaste was still present after experiencing several molts, but was no longer present after metamorphosis. The scientists concluded that in order to retain a memory once the organism is a butterfly, it needs to occur in later stages in the larval time period. The scientists then tested larvae more developed than the original group. The scientists’ prior conclusion was correct because the butterflies that were tested later in their life remembered their distaste for the odor. Additionally, it is possible that this field suffers from the file drawer problem because in the documentation of this study it stated that there were no competing studies.
Overall, butterflies are able to remember some stuff from their caterpillar life, but from what I can see here it is strictly biological and in relation to their well-being. I doubt that the butterflies can remember personal experiences that they had as a caterpillar, but then again I don’t even know if insects even have those.
Source 1: Miorelli, Nancy. “What Happens Inside a Cocoon?” Ask an Entomologist. N.p., 07 Mar. 2015. Web. 21 Nov. 2016.
Source 2: Blackiston, Douglas, Elena Casey, and Martha Weiss. “Retention of Memory through Metamorphosis: Can a Moth Remember What It Learned As a Caterpillar?” PLOS One. PLOS, 5 Mar. 2008. Web. 21 Nov. 2016.