Dorsal fin
A fin on the back of a fish that helps stabilize its movement. Its shape and structure vary among species and can also serve other functions.
Hydrodynamic stability: The tendency of a body moving through a fluid to resist or recover from disturbances to its motion. The dorsal fin can reduce unwanted rolling as a fish swims.
Fish: Aquatic vertebrates with gills and, in most species, fins. Dorsal fins are anatomical structures of fishes.
Shark fin: A fin of a shark, including its typically prominent first dorsal fin. Shark dorsal fins are conspicuous examples with varied shapes and ecological roles.
Tuna: A group of fast-swimming marine fishes in the tribe Thunnini. Tunas have a second dorsal fin followed by small finlets.
Fin ray: A supporting element in a fish fin, made of bone or cartilage, that helps shape and stiffen the fin. Fin rays give many dorsal fins structural support and flexibility.
Fish anatomy: The body structures and organ systems of fishes. Its anatomical position is defined by the fish’s back and midline.
Dorsal fin (cetacean): A dorsal fin on a whale, dolphin, or porpoise, formed from connective tissue rather than fin rays. Cetacean dorsal fins share the name but differ from the fish structure defined here.
Mola mola: The ocean sunfish, a large marine fish with a tall dorsal fin and truncated body. Its tall dorsal fin is a distinctive feature of an unusual body plan.
Median fin: A fin located along the midline of a fish, including dorsal, anal, and caudal fins. The dorsal fin is one of the fins positioned along a fish’s midline.
Fin: A flattened appendage used by aquatic animals for movement, steering, or stability. The dorsal fin is one specialized type of fin.