What “true spider” usually means
In hobby conversation, “true spider” is often used informally for araneomorph spiders—the large branch that includes jumping spiders, orb-weavers, huntsman spiders and many familiar house spiders. It is not a formal rank that excludes tarantulas from being spiders.
Tarantulas are mygalomorphs
Tarantulas share Mygalomorphae with trapdoor spiders and their relatives. One obvious anatomical difference is fang orientation: mygalomorph fangs work mainly downward and in parallel, while araneomorph fangs oppose one another more strongly.
What all spiders share
Tarantulas still have the basic spider body plan: eight walking legs, two main body regions, pedipalps, chelicerae with fangs and spinnerets for producing silk.
Terms to remember
- Order: Araneae
- Family: Theraphosidae
- Suborder/infrastructure: Mygalomorphae
- “True spider” is informal hobby wording, not a statement that tarantulas are not spiders