What arachnid order contains all true spiders?

The arachnid order containing all true spiders is Araneae.

Araneae is the scientific order that includes every living spider, from orb-weavers and jumping spiders to tarantulas and trapdoor spiders. Spiders are arachnids, but they are not insects: adults have eight legs, two main body regions joined by a narrow pedicel, and specialized mouthparts called chelicerae.

The order is divided into major lineages including Mesothelae and Opisthothelae. Opisthothelae contains Mygalomorphae, such as tarantulas, and Araneomorphae, which includes most living spider species. Araneomorphs are often called true spiders in a narrower anatomical sense, but the quiz’s wording uses “true spiders” to mean spiders as opposed to other arachnids.

Spiders are distinguished by features such as spinnerets and silk production, though silk is used for more than webs: it can anchor retreats, protect eggs, help movement, or assist with prey capture. Another common mix-up is treating Solifugae, Amblypygi, or Scorpiones as spiders; those are separate arachnid orders.