The dwarf sperm whale is the smallest of all whales. The species makes slow, deliberate movements with little splash or blow and will usually lie motionless when at the sea's surface. Consequently it can be observed only in very calm seas.
The dwarf sperm whale is physically very similar to, and has the same behavioural characteristics as, its cousin the pygmy sperm whale. Identification may be close to impossible at sea – however, the Dwarf is slightly smaller and has a considerably larger dorsal fin. The body is mainly bluish grey with a lighter underside with slightly yellow vein-like streaks possibly visible. There is a white false gill behind each eye. The flippers are very short and broad. The top of the snout overhangs the lower jaw, which is small.
Like the other Sperm Whales, the dwarf sperm whale has a spermaceti organ in its forehead. Like the pygmy sperm, the dwarf is able to expel a dark reddish substance when frightened or attacked – possibly to put off any predators.
Dwarf sperm whales are usually solitary creatures but have occasionally been seen in small groups