(Photo by SteveD)
The Spinner Dolphin (Stenella longirostris) is a small dolphin found in off-shore tropical waters around the world. It is famous for its acrobatic displays in which it spins along its longitudinal axis as it leaps through the air. They have small, pointed flippers and curved dorsal fins at the center of their bodies. Spinner dolphins are typically dark gray on their dorsal (top) sides with a lighter gray area that runs from their eyes to their tails. Their ventral (under) side is white. Spinner dolphins are a very gregarious species frequently traveling together in schools and with other species, such as spotted dolphins and humpback whales. In the eastern tropical Pacific, spinner dolphins swim with yellowfin tuna, which has resulted in great numbers of spinner dolphins caught as bycatch in purse-seines. The characteristic spinning of this species is thought to be used for communication as it is often observed when a school is scattered. Another theory is that the spinning may be related to the removal of parasites or of remoras.