Sharks and tuna share the same basic streamlined body plan, with locomotion driven by moving fins. They share other structures such as gills. They differ in some details, such as the mineralization of the tuna’s skeleton and the tiny rays which support the tuna’s delicate fins. Tuna also have a swim bladder and a bony operculum covering their gills.
Work Step by Step
Just scan through the text about both ray-finned fishes and the cartilaginous fishes, making a list of similarities and differences. Comparing images of these two kinds of fish may also help.