Fish General - 6 of 7
Fish General FAQs - 7 Found
Yes. Gas bladders, more commonly referred to as swim bladders, allow precise control of buoyancy because the volume of gas they contain can be regulated with ease. Two types of swim bladders exist. Some fish have swim bladders with a connection or duct to the gut. The swim bladder is inflated by gulping air at the water's surface and forcing it through the duct into the swim bladder. Deflation occurs by a reflex action initiated when reduced external pressure makes the fish too light, releasing gas by way of the duct into the esophagus. The other type of swim bladder is a 'closed' system. Special structures associated with the circulatory system are used for inflating or deflating. The structure is a tight bundle of capillaries. This vascular arrangement provides an efficient, countercurrent exchange of blood gases, allowing gas pressure to increase within the swim bladder.