He based this on the head of an individual washed up on the coasts of Audierne in France in 1784, which was then stored in the Muséum d'histoire naturelle.

He noted its small size and nicknamed it "cachalot a tête courte"–small-headed sperm whale; further, the species name breviceps is Latin for "short-headed".

[10] The dorsal fin is very small and hooked; its size is considerably smaller than that of the dwarf sperm whale and may be used for diagnostic purposes.

[11] Dwarf and pygmy sperm whales possess the shortest rostrum of current day cetaceans with a skull that is greatly asymmetrical.

[18] The rostroventral dura of the brain contains a significant concentration of magnetite crystals, which suggests that K. breviceps can navigate by magnetoreception.

When closing in on prey, the click repetition rate starts at 20 Hz and then begins to rise when nearing the target.

[16] Fat from the core of the spermaceti organ helps direct sonic energy from the museau de singe to the melon.

[16] The melon acts as a sonic magnifier and gives directionality to sound pulses, making echolocation more efficient.

[citation needed] Like in most odontocetes, the known echoreception apparatus used by the pygmy sperm whale is linked to the fat-filled lower mandibles within the skull.

[16] However, compositional topography of the pygmy sperm whale's skull indicates abnormally large fatty jowls surrounding the mandibles, suggesting a more intricate echoreception apparatus.

[16] Additionally, an unusual cushion structure, of porous and spongy texture, found behind the museau de singe has been hypothesized of being a possible "pressure receptor".

[16] The positioning of this cushion structure in close proximity to the largest cavities closest to the museau de singe may suggest that it is a sound absorber used for echoreception.

[21] Newborn calves are about 1.2 metres (3 ft 11 in) in length, weighing 50 kg, and are weaned around one year of age.

[26] Analysis of stomach contents suggests that pygmy sperm whales feed primarily on cephalopods, most commonly including bioluminescent species found in midwater environments.

They have also been reported to eat some deep-sea shrimps, but, compared with dwarf sperm whales, relatively few fish.

Both species have a sac in the lower portion of their intestinal tracts that contains up to 12 liters of dark reddish-brown fluid, which can be ejected to confuse or discourage potential predators.

[31][32] However, they are rarely sighted at sea, so most data come from stranded animals - making a precise range and migration map difficult.

Fossils identified as belonging to K. breviceps have been recovered from Miocene deposits in Italy, Japan, and southern Africa.

[34] They were not as heavily hunted as their larger counterpart Physeter macrocephalus, the sperm whale, which are typically 120,000 lb, thus preferred by whalers.

[35] The pygmy sperm whale is also rather inactive and slow rising when coming to the surface and as such do not bring much attention to themselves.

[39] Pygmy sperm whales have been reported as being forced to change their diets and foraging behaviors due to anthropic factors such as deep-sea trawling and increased fishing for cephalopods off the coast of many Southeast Asian countries.

[36] Anthropogenic noise caused by military activity and shipping is another issue affecting this species, as it echolocates.