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How do chondrichthyans differ from bony fishes?
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chondrichthyan
Southern stingrays (Dasyatis americana or Hypanus americanus) are found in the western Atlantic Ocean.
Chondrichthyans (cartilaginous fishes, such as sharks, rays, and chimaeras) differ from bony fishes in several fundamental ways:
- Skeleton: The chondrichthyan skeleton is composed primarily of cartilage rather than true bone, which characterizes the bony fishes.12
- Gills: Chondrichthyans typically have five to seven external gill slits, whereas bony fishes possess a single, movable bony cover called an operculum over the gill chamber.13
- Scales: Chondrichthyan scales, known as dermal denticles, are structurally similar to teeth and do not grow throughout the animal's life; instead, new scales form as the body grows. Bony fishes generally have platelike scales that grow with the fish.12
- Buoyancy: Most bony fishes possess a swim bladder for buoyancy, a structure absent in chondrichthyans.42
- Reproduction: Chondrichthyans exclusively employ internal fertilization, often using specialized male organs called claspers. While bony fishes exhibit diverse reproductive strategies, they frequently utilize external fertilization.4562