Osteichthyes or bony fish have the same organs as amphibians, reptiles, birds, and mammals. They are only differentiated by the presence of gills and swim bladder. Their musculature is concentrated around the spine and the tail. Chondrichthyan fish or cartilaginous fish have the same organic structure as bony fish, except for the swim bladder. There are 620 species of chondrichthyan fish. Cyclostomus fish, which, with no jaws or teeth, are little more than a long digestive channel, have thin pharyngeal sacs instead of gills. There are 45 species of cyclostomus fish. This infographic from the Ábaco collection belongs to the Amphibians and Fish series, which also includes those originally titled: What Is an Amphibian?, Metamorphosis, Bony fish and Cartilaginous.