Metamorphosis

We explain what metamorphosis is and how it occurs in butterflies, frogs, bees and dragonflies. Also, Kafka's “The Metamorphosis.”

butterfly metamorphosis
Metamorphosis occurs at a specific time and under specific conditions.

What is metamorphosis?

In biology, metamorphosis It is the process of structural and physiological changes through which certain animals reach adulthood leaving behind the characteristics obtained from birth. This is a natural process, common to numerous species of insects, mollusks, amphibians, crustaceans, cnidarians, echinoderms and tunicates.

The changes involved in this biological process can be more or less radical, depending on the type of metamorphosis:

  • Complex or complete metamorphosis (holometabolism). It occurs when the characteristics of the initial stages of the animal, say, the larva or its primary stages, are radically different from those of adult life. That is, when the animal completely and significantly changes its ways of life, its anatomy and even its habitat of existence, after going through a stage of inactivity and profound transformation.
  • Simple or incomplete metamorphosis (hemimetabolism). It occurs, on the contrary, when the changes that the young form of the animal goes through are not so radical, since its larval or young stage is not so different from its adult stage. Generally these stages are distinguished only in size, and the animal goes through different “moults” or partial changes, until reaching adulthood.

Both types of metamorphosis are controlled by a diverse set of hormones that induce various reactions and biochemical changes in the body. This process, in addition, is usually related to the climatic and biological cycles of nature, so that they always occur at a certain time and under certain conditions.

Metamorphosis has captivated the attention of human beings since ancient times, leading them to explain it through the most diverse theories, and also becoming a metaphor for change, growth and the life cycle itself, especially that which involves animals. like bees or butterflies, very present in human culture since its beginnings.

See also: Living beings

The metamorphosis of the butterfly

butterfly chrysalis metamorphosis
The butterfly usually places its chrysalis under a branch.

The metamorphosis of butterflies is probably one of the best known and studied by humans, and in total it includes the following stages:

  • The egg. The initial stage in a butterfly's life occurs when an egg is deposited in the environment (on a branch or leaf, or wherever depending on the species) and then fertilized. Generally this occurs in strategic places, using viscous substances, and several eggs are usually deposited. Each one matures, as the life inside it reaches the necessary point, and finally hatches, releasing a larva, which we commonly know as a caterpillar.
  • The caterpillar. Butterfly larvae, called caterpillars, are very popular in gardens, and are elongated animals like a worm, equipped with numerous legs and a robust, spherical head, with powerful jaws capable of crushing leaves, stems and other plant fibers from which the caterpillar feeds. Caterpillars can have antennae, protuberances, very different colors characteristic of the species, and many are even poisonous, but they all have their main goal in common: eating. They feed frantically until they accumulate in their bodies just the right size and energy to undertake the process of metamorphosis. Then, they find the right place, usually hanging upside down from a branch, and weave a cocoon of silks or other fibers that they themselves produce. There they lock themselves up to become adults.
  • The chrysalis. Once inside the cocoon woven by themselves, the caterpillars become chrysalises or pupae, and lead a motionless life that lasts about three weeks. During this time, the caterpillar's tissues modify, dissolve and build, until they adopt the form of a complete adult (imago). As this happens, the chrysalis also hardens, until, when the time comes, and thanks to the pressure that the animal exerts from within, it cracks, allowing an adult butterfly to emerge.
  • The adult butterfly. After breaking the chrysalis, the butterfly unfolds its newly hatched wings and lets them dry and fill with hemolymph. Meanwhile, it fully emerges and, still hanging in place, prepares for flight. It is already an adult individual, ready to lead an aerial life, feeding on the nectar of flowers and other similar fluids, and to reproduce and begin the cycle again.
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The metamorphosis of the frog

frog metamorphosis
In their larva stage, frogs are called tadpoles and have a 100% aquatic life.

Another well-known case is that of most batrachians, frogs and toads. These amphibian animals are the evolutionary step between aquatic and terrestrial life, and for that reason they must always reproduce in water. Its life cycle includes the following stages:

  • The eggs. The life of the frog begins when a female deposits her eggs in a body of water, such as a river, a lake or a puddle of some kind, next to a male who immediately proceeds to fertilize them. The eggs then mature, as the life inside them reaches the right point, and hatch to release tadpoles.
  • The tadpoles. This is the name given to the “larvae” of frogs, that is, their infantile forms, which lead a 100% aquatic life. In fact, they have long, limbless bodies, similar to fish, equipped with tails, gills and a wind blower to hold on to objects. Tadpoles live for about three months, feeding on everything possible, during which they gradually change, as they accumulate the energy necessary for metamorphosis. Then, the changes begin: the hind legs begin to sprout, then the front ones, and the body increases considerably in size. The lungs develop inside the young frog, as the tail and gills are gradually reabsorbed, preparing the animal for its future terrestrial life.
  • The adult frog. Once metamorphosis is complete, an adult frog leaves the water and begins adult life in the dry, although returning from time to time to hydrate and lay eggs, thus repeating its life cycle.

The metamorphosis of the bee

bee metamorphosis
The bee undergoes metamorphosis within a cell of the hive.

Despite living an organized life in their respective hives, the metamorphosis of honey bees is well known to biology. And it includes the following life cycle:

  • The eggs. Bee eggs are always laid by the queen bee, the only one capable of reproducing, inside special cells of the hive, intended to house the young, instead of honey. The eggs are white and flat, oval in shape, and hatch after about three days.
  • The larvae. Freshly hatched from the egg, the larvae rest in a “C” shape in their respective cells, waiting for the worker bees to bring them their food: a kind of honey-based jelly, made by themselves. The larvae are white, elongated and have a segmented body, but without limbs and totally blind. They will be fed in this way until they reach the size necessary to become pupae or chrysalises.
  • The chrysalises. When they are ready for metamorphosis, the larvae generate a characteristic odor that the workers recognize, and they proceed to seal each cell with wax, isolating the larva from the outside. Inside, hidden from the light, the larva undertakes a period of inactivity and changes that varies according to the final role that the individual will have in the hive: workers, drones or queens.
  • adult bees. Once the adult or imago stage has been reached, the bees emerge from their cells to join the complex social life that characterizes these insects.
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The metamorphosis of the dragonfly

dragonfly metamorphosis
The adult dragonfly emerges from the water and loses its outer bark.

The dragonfly, popularly known as “damselfly” or “aguacil”, is another insect that undergoes metamorphosis into insects: the dragonfly. An individual of this species can live more than one year, during which it will have completed the next cycle of life and changes, allocating the smallest amount of that year to adulthood.

  • The eggs. Like the rest of the insects, the dragonfly is born from an egg, laid by a fertilized female, since dragonflies mate in mid-flight. The eggs are generally laid on aquatic plants, or released into the water of rivers, lakes or ponds.
  • The nymph. The larval stage of the dragonfly is also known as the nymph, and begins when an egg hatches and releases a humpbacked underwater creature whose feeding is constant and based on smaller creatures. This life stage can be quite long, since metamorphosis does not begin until the weather conditions are suitable for the nymph to emerge from the water. But in the meantime, the nymph will undergo a series of molts and transformations, which will strip it of its hump and give it small nymphal wings, as well as the trachea apparatus necessary to replace the gills.
  • The adult dragonfly. When ready to emerge from the water, the nymph will look for some aquatic plant to attach itself to and begin its ascent toward the surface, during which it will lose its outer bark (called exuvia) and emerge from itself as an adult. From then on, it will have a flying life, although restricted to a few months: enough to reproduce and restart the cycle.
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“The Metamorphosis” by Franz Kafka

The metamorphosis (Die Verwandlung in German), sometimes published as The transformation, is a story written by Czech author Franz Kafka (1883-1924) published in 1915. It is probably the best known of all his work.

This is the story of Gregorio Samsa a 23-year-old traveling salesman, who One day he wakes up in his bed turned into a gigantic beetle. This makes it impossible for him to carry out his work, on which his entire family depended.

Finally, unable to communicate with his family and mistakenly hurt by his father, who on one occasion believed that the insect was caring for his own mother, Gregorio Samsa dies from an infected wound in his side. His body is found by the shop assistant, who throws it in the trash, and the family continues its existence, a little relieved deep down.

The metamorphosis has given rise to numerous interpretations, some of an autobiographical nature, but It is considered one of the most outstanding works of literature in German of the 20th century. Especially since it was written by a Bohemian Jew almost two decades before the tragic events of World War II, in which the Jewish population of Europe was enslaved and annihilated, treating them as if they were less than human beings.

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References

  • “Metamorphosis (biology)” on Wikipedia.
  • “Metamorphosis” in the language dictionary of the Royal Spanish Academy.
  • “Kafka's Metamorphosis: Summary and Analysis” (video) in Reo de nocturnidad.
  • “What is metamorphosis?” in Hidden Nature.
  • “Metamorphosis (biology)” in The Encyclopaedia Britannica.