While often referred to as "spinning" a cocoon, the process performed by a silkworm is more accurately described as extruding silk fibre and forming a cocoon. The term 'spinning' in the context of textile production, as defined by the reference, refers to a different process applied after the silk fibre is produced.
Here's a breakdown of what happens:
The Silkworm's Biological Process
The silkworm (the larva of the silk moth Bombyx mori) doesn't spin itself in the traditional textile sense. Instead, it produces a continuous filament of silk from special glands.
- Silk Gland Activity: Inside the silkworm, two large silk glands run along its body. These glands produce a liquid protein called fibroin.
- Sericin Coating: The fibroin is coated with another protein, sericin, which acts as a natural gum, helping the strands stick together.
- Extrusion: The liquid silk is forced out through spinnerets located on the silkworm's mouth.
- Hardening: Upon contact with air, the liquid protein hardens into a solid, continuous filament.
- Cocoon Formation: The silkworm then moves its head in a figure-eight motion, carefully winding the silk filament around itself to create a protective casing called a cocoon. This process takes several days.
This biological action of extruding the filament and winding it into a cocoon is often colloquially called "spinning" the cocoon, but it's distinct from the textile manufacturing process that follows.
Textile Spinning of Silk Fibre
The silk filament produced by the silkworm is the raw material for silk yarn. After harvesting and processing the cocoons (often involving killing the pupa inside and softening the sericin), the long, continuous filament is reeled off the cocoon. This reeled silk is then prepared for textile production.
According to the provided reference:
- Spinning Definition: Spinning is the process of winding together drawn-out strands of fibres to form a yarn. It is a major part of the textile industry.
- Application to Silk: While silk's natural long filament (up to 1,000 meters!) means it often requires less spinning than shorter staple fibres like cotton or wool, the reeled filaments are still twisted together, sometimes with multiple ends, to create stronger yarn of a desired thickness. Shorter silk fibres, known as "silk waste," are definitely spun using textile methods.
- Spinning Methods: The reference mentions different types of spinners used in the textile industry, such as Ring, Rotor and Air-jet spinners. These machines are used to process various textile fibres, including silk (especially silk waste), into yarn by twisting the fibres together.
In summary: A silkworm produces silk fibre and forms a cocoon by extruding and winding this fibre. The term 'spinning', in the textile industry sense (as defined by the reference), is a subsequent process where collected silk fibres (long filaments or shorter waste fibres) are twisted together to create yarn suitable for weaving or knitting.
