Fins are flat, thin structures found on the bodies of many aquatic animals, such as fish and whales. They help these creatures swim efficiently through water by providing stability and control. Fins can vary in shape and size, depending on the species and their environment. For example, the long fins of a tuna allow it to swim quickly, while the broad fins of a manta ray help it glide gracefully. In addition to aiding in movement, fins also play a role in communication and mating displays. Some fish use their colorful fins to attract partners or signal to others. Overall, fins are essential for the survival and behavior of many marine animals.