Book lung
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A book lung is a type of respiration organ used for atmospheric gas exchange present in some arachnids such as scorpions and tetrapulmonates. It is a terrestrial adaptation of the book gills seen in a
In this spider diagram, the position of the book lungs is labelled 1.
Underside of female horseshoe crabs showing the legs and book gills
Opiliones
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The Opiliones are an order of arachnids, colloquially known as harvestmen, harvesters, daddy long legs, or granddaddy long legs. Over 6,650 species of harvestmen have been discovered worldwide, althou
Book lung
…In most arachnid species, passive ventilation alone is sufficient to facilitate respiration needed for metabolism. Many arachnids, such as mites and harvestmen, have no traces of book lungs and breathe through their body-surfaces only or through tracheae. Gas exchange is performed by the thin walls inside the…
Opiliones harvestman
Chilean harvestman (Pachyloidellus goliath)
North European harvestman (Leiobunum rotundum) body
A harvestman (a male Phalangium opilio), showing the almost fused arrangement of abdomen and cephalothorax that distinguishes these arachnids from spiders