The juveniles have black bands on their bodies and fins but these fade as they grow into adults. This is a type of coloration known as countershading, and it is found in many types of animals including fish, reptiles, mammals, and birds. The purpose of countershading is to provide camouflage from predators or prey. When an animal is viewed from above, the darker color on its back absorbs more light than the lighter color on its belly. This makes the animal appear flattened and less visible. When viewed from below, the opposite occurs and the animal appears much brighter against a dark background. Countershading works because it breaks up an animal's outline so that it becomes harder to spot.