Which whale species is known as the 'greyhound of the sea'?

The fin whale is known as the “greyhound of the sea.” Its long, streamlined body and powerful tail make it one of the fastest large whales, capable of sustained high-speed swimming and short bursts even faster.

The fin whale (Balaenoptera physalus) is a baleen whale and the second-longest cetacean after the blue whale. It feeds by filtering small fish, squid, krill, and copepods through baleen plates rather than using teeth.

Its speed helped inspire the nickname, but the comparison is also a useful clue to its shape: fin whales are slender, muscular, and built for efficient travel across open oceans. They are sometimes confused with blue whales, yet fin whales usually have a more sharply ridged back and distinctive asymmetrical coloring around the head.

Fin whales range through all major oceans. Commercial whaling severely reduced their numbers during the nineteenth and twentieth centuries, although some populations have since begun recovering.