The Slender-billed Prion is a member of the distinctive genus Pachyptila, the prions. Apart from their small size, from afar their general appearance is similar to most procellariids being darker and patterned above and white below. Their most distinctive attribute are broadened mandibles with the upper mandible fringed with lamellae, which is used to filter plankton from the ocean. The Slender-billed Prion feeds using two alternative methods, either ‘surface-seizing’ while pattering over the water or by ‘dipping’ their bills into the water while in flight. The Slender-billed Prion is the most distinctive species of prion due to its very slender bill with which it takes mostly marine crustaceans, though this character is fairly difficult to see well in the field. It occurs in small flocks in the pelagic waters off of South America and in the south Indian Ocean from New Zealand to Africa.