What is "caudal fin"?

The caudal fin is a large, fan-shaped fin located at the tail end of fish and other aquatic animals such as whales and dolphins. It is composed of a central bony or cartilaginous structure called the hypural plate and is supported by numerous fin rays. The shape and size of the caudal fin vary among species and can be an important characteristic for identifying different types of fish. The caudal fin is primarily used for propulsion and steering, with the different shapes reflecting adaptations to different swimming styles and habitats. For example, fish with a deeply forked caudal fin, such as tuna and marlin, are able to swim at high speeds over long distances, while those with a rounded or square caudal fin, such as catfish, are better suited for maneuvering in tight spaces.