1. Have you ever stopped to consider the door? This most mundane of architectural elements might surprise you. For example, humans are not the only species to construct doors.
2. Aptly named trapdoor spiders have evolved some spectacular ambush hunting techniques. The arachnids make doors for their burrows out of dirt and silk, camouflaged with leaves and other material. The doors even have hinges.
3. Some trapdoor spider species spin additional silk lines around the door to function as tripwires when prey wanders past.
