Dusky dolphins, originally named Fitzroy's dolphins by Charles Darwin, are easily distinguished from other dolphins. The head is small and evenly sloped, and there's no beak at the end of the snout. The tail and back are bluish black in color, with a dark band that runs diagonally from the flank to the tail. The belly is white, and there's a two-pronged blaze in white or cream from the dorsal fin to the tail. Dusky dolphins are extraordinarily social, sometimes traveling in pods with as many as 1,000 members. They're also highly acrobatic—watch to see them leaping out of the water to turn somersaults in the air. Their squeals, whistles and clicks can sometimes be heard as far as three kilometers (two miles) away.