Lung | Book

Because these organs are essentially open to the air, they are prone to drying out. This is why many spiders require high humidity to breathe effectively. 💡 Key Evolution Fact

Most arachnids don't "inhale" or "exhale" like we do. Air simply flows into the spiracles and oxygen diffuses into the hemolymph naturally.

While book lungs are common, some smaller spiders also use a (a network of tubes). book lung

The folded design creates a massive surface area in a small space, maximizing oxygen absorption. How They Work

These are the spaces between the "pages" where air circulates. Because these organs are essentially open to the

Better for surviving in arid environments because they are more water-efficient.

More efficient at delivering high amounts of oxygen to very active insects. Air simply flows into the spiracles and oxygen

A "book lung" is a specialized respiratory organ used for atmospheric gas exchange by many arachnids, such as spiders and scorpions. Unlike human lungs, these organs are not connected to a complex throat or nose system; instead, they open directly to the outside air through small slits on the abdomen called spiracles. Anatomy of a "Book"