Dolphins (Jay Ebberly / CC BY)

Dolphins (Delphinidae) are toothed whales with torpedo-shaped bodies and cleaved flukes. Their forelimbs have evolved into flippers. Dolphins range from 1.4 meters (4.6 feet, Hector's dolphin) to 9 meters (30 feet, orca) in length. Dolphins generally interact well with humans, and their behavior is sometimes even playful.

More images » More info »

This supplemental online resource accompanies the book Scuba Diving Hand Signals by Lars Behnke, available on Amazon.