Physical Description
The Dwarf sperm whale is the smallest species commonly known as a whale. It grows up to 2.7 m (8.9 ft) in length and 250 kilograms (550 lb) in weight— making it smaller than the bigger dolphins. The species makes slow, deliberate movements with little splash or blow and usually lies motionless when at the sea's surface. Consequently it is usually observed only in very calm seas (Beaufort 0-1).
The Dwarf sperm whale is similar in appearance and behavior to its cousin the Pygmy sperm whale. Identification may be close to impossible at sea – however, the Dwarf is slightly smaller and has a larger dorsal fin. The body is mainly bluish gray 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. Dwarfs have long, curved and sharp teeth (0–6 in the upper jaw, between 14 and 26 in the lower). These teeth led to the species being described as the "rat porpoise" in the Lower Antilles.
Like other sperm whales, the Dwarf sperm whale has a spermaceti organ in its forehead. Like the pygmy, 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 but have occasionally been seen in small groups. They feed mainly on squid and crab.
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