A TAN­GLED WEB

Science Illustrated - - BIODIVERSITY -

Spi­ders orig­i­nally evolved silk to wrap and pro­tect their eggs. While not all spi­ders build webs, all species do pro­duce silk and all also wrap their eggs in the suff. The older the spi­der’s lin­eage (ie, the less it has changed over time), the more prim­i­tive its silkpro­duc­ing sys­tems. Taran­tu­las – in­clud­ing the Syd­ney Fun­nel-Web – are among the most prim­i­tive, silk­wise, and can’t even re­ally make lines. They only make sheets they use to build their nests. Other spi­ders have adapted silk for all kinds of elab­o­rate sys­tems, from huge clas­sic-style webs strong enough to trap birds, to webs that are held in two legs and thrown over prey like a net. Even tiny jump­ing spi­ders – who don’t build webs – nev­er­the­less use silk as drag-lines and teth­ers, in way that would make the most ex­treme park­our ex­pert blanch.

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