The dwarf sperm whale is similar to the pygmy sperm whale, but is smaller and has a larger, taller dorsal fin, higher on its back, that looks like the dorsal fin of a bottlenose dolphin. Dwarf sperm whales live in small social groups. Learn more about the Kogia simus, more commonly known as a Dwarf Sperm Whale, in this easy-to-read species overview by the Smithsonian's National Museum of Natural History.