Classification: 

Dwarf sperm whales are small whales — smaller even than some dolphins. Recent genetic studies suggest that there may actually be two separate species of dwarf sperm whales, one in the Atlantic and one in the Indo-Pacific. It is extremely similar to its close relative, the pygmy sperm whale and usually indistinguishable when spotted at sea. The dwarf sperm whale also releases a cloud of reddish-brown intestinal fluid before diving when startled. It could be a nervous reaction or possibly a defence mechanism. This may act as a decoy similar to that of squid ink.

Appearance: 

Compared to the pygmy sperm whale, the dwarf sperm whale has a more pointed snout, giving its head a more conical appearance with the single blowhole set slightly left of centre. It is also smaller, with a flatter back. Its skin is dark blue to olive brown on the dorsal side, becoming paler on the belly, which can sometimes be pinkish, with a whitish circle above the eye. The dwarf sperm whale also has the small underslung jaw and false gill that cause it to be confused with sharks. It has a taller, more pointed dorsal fin than the pygmy sperm whale which, ignoring behaviour, can cause it to be mistaken with bottlenose dolphins in the wild. Its teeth are long, curved, and very sharp, with 7 to 13 pairs in the lower jaw and often 3 pairs in the upper jaw.

Behaviour: 

Dwarf sperm whales are slow, deliberate swimmers and have been seen floating motionless at the surface. Like pygmy sperm whales, dwarf sperm whales rise slowly to the surface and drop out of sight rather than diving. They don't seem to approach boats, though they are sometimes seen basking on the surface and may allow boats to approach them. Some records note that, when resting on the surface, they float lower in the water than pygmy sperm whales. They generally travel in groups of fewer than 10 animals.