Pirate spiders ambush prey by tricking them with lines of silk

A species of pirate spider in Costa Rica has a unique hunting strategy: It attacks other spiders that use its silk lines as scaffolding for their own webs.

Many spiders build webs to snare prey, but their web design and purpose can vary widely depending on where they live and what they hunt. Some webs are flat sheets, while others form tube-like funnels or spiralling orbs. Other species forgo web-building altogether, and instead chase down or ambush prey. …