Ray-finned fish are a diverse group of fish characterized by their bony skeletons and fins supported by thin, bony rays. They belong to the class Actinopterygii, which is the largest class of vertebrates, including over 30,000 species. These fish inhabit various environments, from freshwater rivers to the deep sea. Their fins are flexible and allow for precise movements, making them efficient swimmers. Ray-finned fish have a swim bladder, an internal gas-filled organ that helps them maintain buoyancy. Common examples include salmon, trout, and tuna, which are important for both ecosystems and human consumption.