Gill rakers are bony or cartilaginous outgrowths that project from the branchial arch of fish and assist in feeding by preventing stray particles or loose pieces from exiting through the gills. The size and arrangement of the gill rakers can signify what the fish eats.
Gill rakers that are fine and comb-like serve as filters for plankton or suspended particles, similar in mechanism to a whale's baleen. Short, widely spaced gill rakers are suitable for carnivorous fish that eat larger prey, while longer and thinner gill rakers are effective for consuming smaller prey. Gill rakers are a suitable method for differentiating and identifying fish, as they can vary in closely related species.