What is fin?

Fins are appendages of aquatic animals that help them swim through the water. They come in a variety of shapes and sizes, and are composed of different materials depending on the animal they belong to.

Fish fins are typically symmetrical and have a series of bones or cartilage structures known as rays. The rays support the fin and enable the fish to move through the water with precision and agility. Most fish have dorsal (top), anal (bottom), and paired pectoral and pelvic fins (sides). Some fish, such as anglerfish, also have modified fins that serve as lures to attract prey.

Marine mammals, such as dolphins and whales, have evolved fins that are more similar in structure to limbs than traditional fins. These limbs – known as flippers or flukes – allow marine mammals to navigate and propel themselves through the water with great speed and maneuverability.

Fins are also used in the world of human water sports, such as swimming, diving and surfing. Swimmers often use fins to increase their speed and improve their technique, while divers use fins to help them move through the water with minimal effort. Surfers use fins to enhance their board's control and stability.