Metamorphosis is one of the most amazing processes in nature. This event, which we can define as the transformation of an animal from one form to another, usually leads to a great change in the appearance and behavior of living things. Some of the best-known examples of metamorphosis are butterflies and moths, which go through four developmental stages: egg, larva (caterpillar), pupa (chrysalis), and adult (butterfly).
In the pupal stage, the caterpillar’s body; completely rearranged to produce the adult butterfly or moth. Tissues and organs are broken down and rebuilt, some parts are discarded or recycled. This begs the question in the title.
First we need to learn this: How does memory work in butterflies and moths?
Memory is the ability to store and recall information based on past experiences. This phenomenon, which can be divided into different types such as short-term memory (lasting from seconds to minutes) and long-term memory (lasting from days to years), can also be classified according to how it is acquired: for example declarative memory (involving the conscious recall of facts and events) and non-declarative memory (involves unconscious learning of skills and habits).
Although butterflies and moths have a relatively simple nervous system compared to humans, they do have some memory and learning capacity. They have a brain made up of several clusters of neurons called ganglia connected by nerve cords.
The most important part of the brain for memory and learning is the cork body, which is involved in sensory processing, associative learning, and decision making. The fungus body is found in both caterpillars and butterflies but undergoes significant changes during metamorphosis.
Whether the butterflies retain their memory after metamorphosis had to be tested.
Scientists have long wondered if butterflies and moths remember learning as caterpillars, but testing this hypothesis has been difficult because of the drastic changes that occur during metamorphosis. In 2008, a research team from Georgetown University in the USA designed an ingenious experiment to answer this question.
They trained the caterpillars to associate a particular odor (ethyl acetate) with a mild electric shock, which allowed them to avoid it. They then waited for the caterpillars to develop into adult moths and tested whether they still remembered to avoid the same scent.
The results were surprising: Yes, butterflies remember their caterpillar times, but not in the way you might think.
Most adult moths still showed a strong aversion to ethyl acetate, even if they had never encountered ethyl acetate in their adulthood. This indicated that although they had undergone complete metamorphosis, they retained some form of memory from their caterpillar days.
The researchers suggested that this type of memory is non-declarative, meaning that it involves an automatic response based on past experience, not conscious recall. They also suggested that this memory is stored in the cork body, which is preserved during metamorphosis.
This study by Georgetown University was the first, but not the last, to show that butterflies and moths can remember what they have learned as caterpillars. Since then, other researchers have confirmed and extended this finding using different methods and species.
For example, a 2014 study showed that monarch butterflies can maintain their migratory orientation throughout metamorphosis; this helps them travel thousands of miles each year from North America to Mexico.
These studies revealed that metamorphosis is not a complete reset of the nervous system, but rather a complex process that allows some memories to be retained and others to be erased or altered.
As a result, we can say with certainty, according to the studies carried out, that yes, although butterflies remember their caterpillar times, this is not a conscious memory, but a reflex memory transmitted by evolution.
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