Respiratory System of Spiders
WouterA spider’s respiratory system is different from most animals. The respiratory organs of a spider consist of two main types, book lungs and tracheae. Spiders also have a heart, which is located in the abdomen. Some species have both book lungs and tracheae, while others use only one or the other.
Book lungs are tubular structures, usually with a small opening, located on the underside of the abdomen. These lungs never close completely. They are open only when the spider needs to take in air. During the animal’s active life, slits on the tracheae are used to pump blood. Tracheae can be short or highly branched.
Spiders are slow metabolic creatures. Unless you’re a scientist, you might not realize it, but they need oxygen to survive. It’s a minuscule amount, but they require it.
Oxygen is obtained through diffusion through cuticular pores. Pycnogonids are distributed across the world’s oceans, making them an ideal model to study oxygen-temperature interactions. Unlike other sea-dwelling spiders, pycnogonids are not equipped with specialized respiratory organs. Instead, they rely on passive diffusion of oxygen.
Besides using tracheae, spiders have other respiratory organs, such as an air film, which is a thin layer of water that exchanges carbon dioxide with oxygen. During long submersion, spiders will widen their slits to allow more air into their lungs.
Some spiders have tracheae that extend into their cephalothorax. These tracheae are predators. In some spiders, the slits are opened and closed during short bursts of activity.
