What are the 3 groups of fish. What are some of the differences that separate these groups?

The three main groups of fish are jawless fish (agnatha), cartilaginous fish (chondrichthyes), and bony fish (osteichthyes). Jawless fish, like lampreys and hagfish, lack jaws and have a simple body structure. Cartilaginous fish, such as sharks and rays, have a skeleton made of cartilage instead of bone. Bony fish possess a bony skeleton and include the vast majority of fish species, featuring a more complex anatomy, including swim bladders for buoyancy and gills covered by a bony operculum.