Book Lungs True Spiders

The book lungs located inside the arachnid are made up of several thin membranes somewhere between 10 and 80 depending the species.

Book lungs true spiders. Book lungs are a series of very thin leaf like structures like the pages in a book. The inside of each leaf is filled with blood and the outside is exposed to air. Book lung form of respiratory organ found in certain air breathing arachnid arthropods scorpions and some spiders.

Spiders have developed several different respiratory anatomies based either on book lungs or on tracheae. Spiders such as tarantulas in the mygalomorphae infra order and mesothelae suborder have two pairs of book lungs. Some have a pair of book lungs others have several pairs.

Scientists have found that many primitive spider species have the feature of a set of book lungs compared to just one pair. Mesothele and mygalomorph spiders have two pairs of book lungs filled with haemolymph where openings on the ventral surface of the abdomen allow air to enter and oxygen to diffuse in and carbon dioxide to diffuse out. As in the trachea the book lungs exchange oxygen and carbon dioxide through diffusion.

The book lungs are saturated in light blue haemolymph. Each book lung consists of a series of thin plates that are highly vascular i e richly supplied with blood and are arranged in relation to each other like the pages of a book.