Why a spider uses more than one kind of silk
Many spiders produce different silks for different jobs, including structural lines, prey capture and egg protection. Their silk glands make protein mixtures that are processed into fibres through specialised spinning structures. A web is therefore not necessarily built from one identical thread repeated everywhere.
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Different fibres serve different tasks
Spider silk begins as protein-rich material inside silk glands. During spinning, changes in the material and drawing through the spinning apparatus help turn it into a fibre.
Many spiders possess several gland types. The resulting silks can differ in strength, stretchiness or stickiness, matching different functions.
A web can be a combination of materials. In a typical orb web, supporting lines and the prey-catching spiral do not have identical requirements.
- Structural silk supports the framework.
- Capture silk helps retain prey.
- Other silks can wrap eggs or captured animals.
Not all spiders build prey-catching webs, and not every species produces the same collection of silks. The useful general principle is specialised material production, rather than one universal spider thread with every desirable property.