AP BIOLOGY

Detailed explanation-1: -Most bony fishes are covered with the cycloid scales of salmon and carp, or the ctenoid scales of perch, or the ganoid scales of sturgeons and gars. Cartilaginous fishes (sharks and rays) are covered with placoid scales.

Detailed explanation-2: -Many fish have an outer covering of scales. Scales protect fish, much like a suit of armor. All fish have a slimy covering of mucus. This substance allows the fish to swim through the water with very little drag and also makes it difficult for other organism to attach to the fish.

Detailed explanation-3: -Scales. Most species of bony fishes are covered with and protected by a layer of plates called scales. There are four different kinds of bony fish scales: cosmoid, ganoid, cycloid, and ctenoid. True cosmoid scales are found only on extinct Crossopterygians.

Detailed explanation-4: -Ctenoid scales are scales with comb-like edge found in higher order teleost fishes, such as perch and sunfish.

Detailed explanation-5: -Ganoid scales (or modified ganoid scales) are found in fishes such as the bichirs (Polypteridae), Bowfin (Amia calva), paddlefishes (Polyodontidae), gars (Lepisosteidae), and sturgeons (Acipenseridae).