Colouration of most cetaceans is a dark dorsal region and a light ventral region. This is called countershading and prevents detection from predators.

The light coloured underbelly blends with the light penetrating the water surface, making it difficult to detect from below. The dark coloured back blends with the shadowy water below and is difficult to see from above.

The white underbelly and dark back aid in protecting this Harbour Porpoise in the wild from predators like sharks and Killer Whales.