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Silverfish

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The silverfish, known scientifically as Lepisma saccharinum, is a small and primitive insect.

Lepisma saccharina
Lepisma saccharina

It belongs to the order Zygentoma, which is a group of wingless insects. The common name comes from its silvery, light grey color and its fish-like movement. This insect is nocturnal, meaning it is active during the night and avoids light. It is considered a cosmopolitan species because it is found globally. You can find silverfish in Africa, the Americas, Australia, Eurasia, and parts of the Pacific.

Silverfish head close-up
Silverfish head close-up

Physically, the silverfish has a very distinct body shape. Its abdomen tapers at the end to create a look similar to a fish. It possesses two long antennae and two long cerci at the back. There is also one terminal filament located at the tip of the abdomen between the cerci. While some other Zygentoma members are eyeless, the silverfish has two small compound eyes. Young silverfish are born whitish in color. As they mature, they develop a greyish hue and a metallic sheen. They are also quite resilient; they can regenerate lost antennae or terminal filaments within four weeks.

Silverfish have a unique and complex life cycle involving many moults. A moult is when an insect sheds its old exoskeleton to grow. Most insects stop moulting once they reach adulthood, but silverfish are different. They continue to moult even after they become adults. Throughout their lives, they may undergo between 17 and 66 moults. Some individuals may undergo as many as 30 moults in a single year. This process helps them grow from small, white nymphs into adults over a period of three months to three years. Their total lifespan is estimated to be around 2 to 8 years.

Reproduction for the silverfish involves a specific three-phase ritual. This process can last for over half an hour. In the first phase, the male and female stand face to face. They touch their vibrating antennae and then repeatedly back off and return. In the second phase, the male runs away and the female chases him. During the third phase, they stand side by side, head to tail. The male vibrates his tail against the female. The male then lays a spermatophore, which is a sperm capsule covered in gossamer. The female uses her ovipositor to take this into her body. She then lays groups of fewer than 60 eggs in small crevices. These oval, whitish eggs take two weeks to two months to hatch.

The diet of the silverfish is tied closely to its scientific name. The name saccharinum refers to its preference for carbohydrates like sugar and starches.

Silverfish scales
Silverfish scales

They possess an enzyme called cellulase in their midgut. This allows them to digest cellulose, which is a major component of paper. Because of this, they often inhabit libraries, classrooms, and old books.

They consume many items, including book bindings, glue, starch, and dextrin. They may also eat clothing made of cotton, linen, or silk. In times of famine, they might even eat leather or synthetic fabrics. They can survive for a year or more without food if they have access to water.

Because they consume many household items, silverfish are often called pests. They can damage wallpaper by eating the paste or destroy tapestries. However, they do not transmit diseases to humans. They do require moist environments to survive, specifically a relative humidity between 75% and 95%. You might find them in attics, basements, kitchens, or even bathtubs. In the natural ecosystem, they serve as food for predators. House centipedes and certain spiders, such as the spitting spider, hunt silverfish. Scientists have even studied the oil of the Japanese cedar as a way to repel them.

The history of the silverfish is recorded through scientific classification. Carl Linnaeus first described the species in 1758 in his work, Systema Naturae. While the scientific name was established then, the common name has been used since at least 1855. There have been interesting changes in how scientists name them. For a long time, the genus Lepisma was treated as feminine. However, in 2018, the International Commission on Zoological Nomenclature issued a ruling. They decided the gender of Lepisma must be neuter. This changed the formal spelling of the name for many researchers. This demonstrates how scientific language continues to evolve over time.

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🖼️ Images & Media (4)
File:Lepisma_saccharina.jpg
Lepisma_saccharina.jpg
File:Silverfish head close-up.jpg
Silverfish head close-up.jpg
File:Nutritional_traces_of_silverfishs_in_a_book.jpg
Nutritional_traces_of_silverfishs_in_a_book.jpg
File:Silverfish_scales.jpg
Silverfish_scales.jpg
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