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dorsal fin
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internal structure of fishes
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dorsal fin

animal appendage
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internal structure of fishes
internal structure of fishes Internal structure of fishes. (Top) Skeleton of a perch (order Perciformes). (Bottom) Dissection of a perch.

A dorsal fin is an appendage that projects from the back of many fish and some marine mammals, such as dolphins and porpoises. In fish, the dorsal fin, along with caudal and anterolateral fins, plays a crucial role in stabilization and steering while swimming. While most fish have a single dorsal fin, some species possess two or even three. The shape of the dorsal fin can vary; for instance, porpoises have a more triangular dorsal fin, whereas dolphins have a more curved one. This fin helps prevent yawing, or lateral seesawing, movements.123

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4 Britannica Sources
  1. dorsal fin
  2. locomotion - Stabilization and steering
  3. fish - Annotated classification
  4. fish - Body plan

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