Biology

Spider respiration: book lungs and tracheae

Spiders breathe through book lungs, tracheae, or both, depending on lineage. Mygalomorphs (tarantulas, trapdoor spiders) retain two pairs of book lungs; most araneomorphs have one pair plus a tracheal system.

Book lungs

Stacked lamellae in a ventral cavity allow gas exchange across a large surface area. Book lungs require ambient humidity; spider mortality outdoors during low-humidity events is partially explained by respiratory water loss.

Tracheae

Some derived araneomorphs (e.g., Salticidae) have extensive tracheal systems supporting the metabolic demands of active hunting and rapid jumping.

References

  1. [1]Comparative respiratory anatomy of spiders - Journal of Morphology. Accessed June 2026.

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