Humphrey's long black and white tail fin, which is approximately one third of his body length, and pectoral fins have unique patterns that enable scientists to positively identify Humphrey, in a similar way to the bill markings on Bewick's Swans. Several hypotheses have been suggested to explain the evolution of the Humpback's pectoral fins, proportionally the longest fins of any cetacean. The two most accepted hypotheses are that the higher maneuverability afforded by long fins is a significant evolutionary advantage, or that the increased surface is useful for temperature control when migrating between warm and cold climates.