So if the web was made entirely out of dragline silk, an insect is very likely to just bounce right off. But by having really, really stretchy capture spiral silk, the web is actually able to absorb the impact of that intercepted prey.
Portanto, se a teia fosse feita toda de seda de reboque, um insecto iria muito provavelmente ressaltar da teia. Mas, ao ter esta espiral muito, muito flexível, a teia é capaz de absorver o impacto causado pela presa em voo.