Pacific whitesided dolphins are among the fastest, most acrobatic swimmers in the sea. They live in the North Pacific from Alaska to Japan in the west and the Baja Peninsula of Mexico in the east, in both coastal and offshore waters. Sailors often see them riding the bow waves of their boats and jumping, somersaulting and spinning in mid-air. Whitesided dolphins are social mammals, usually traveling in groups of hundreds or even thousands on their wanderings across the Pacific. They grow to be seven and a half feet long and feed on hake, anchovies, squid and sardines. Like all dolphins, whitesides have highly evolved senses of hearing, which they use to navigate and hunt by echolocation. Their life spans are believed to be between 35 and 40 years, and they are prey only to killer whales and large sharks.