The Respiratory System of Spiders
WouterIn many spiders, the respiratory system is remarkably diverse. A number of hypotheses have been proposed to explain this variation. Among these are miniaturization, tracheal morphology, and the role of water loss. However, water loss and tracheal morphology are not the only explanations for the diversity of respiratory organs.
A well-known family of spiders is the Lycosidae. They have a complex arachnid respiratory organ, known as the book lung. It consists of a series of thin plates. It is richly supplied with blood and is used by a variety of species to exchange atmospheric gaseous materials.
In arachnids, the book lung is located in the posterior respiratory system. In smaller spiders, it is present in the anterior respiratory system. Its spiracles open into the atrium. In larger spiders, it is in the prosoma.
In symphytognathoids, the respiratory system is highly variable. The posterior tracheal system is complex, but the anterior tracheal system is simple. This arrangement has evolved from a fully developed book lung. The symphytognathoid family of spiders includes ninety species in eight genera.
Another well-known family is the Salticidae. They have a tracheal system that consists of flat lamellae with a thin cuticle. They are arranged in a leaf-like structure. They are grouped in pairs and connected to the atria by a transverse duct.
In addition to these, spiders have tracheae that have been referred to as tubular lungs. They increase the surface area of the respiratory system, and they have been shown to increase local oxygen demands. They also increase flexibility of the respiratory behavior.
