It wouldn't be wrong to say that the pygmy sperm whale (Kogia breviceps) is the least known marine animal on our planet, as most of the information that we have about this species is derived from specimen that were washed ashore.
Until 1966, it was mistaken for the dwarf sperm whale (Kogia sima), which is also found in the Atlantic and Pacific waters. More recently, however, studies have revealed that the two are different species belonging to the sperm whale family.
Pygmy Sperm Whale Facts
As in case of other sperm whales, even pygmy sperm whales have the 'spermaceti' on their forehead, from which they derive their name. Even though the members of this species are known to lead a solitary life, occasional sightings in groups have also been recorded.
Their tendency to jump and flip all over the place has earned them the name kujira, meaning the firecracker whale, in Japan.
The shy nature of these creatures has kept them off the human radar. While that has been a good thing for this species, it has resulted in us not knowing much about them. Like we said, our 'limited' knowledge about them comes from specimen that were washed ashore by waves.
Size and Appearance
The most striking feature of this species is their head, which is exceptionally big in comparison to their body. Their dorsal fin is smaller than that of dwarf sperm whales with whom they are often confused. The size of their dorsal fin plays a crucial role in differentiating the two species from each other.
Their color ranges from bluish gray to black, with light gray shade on either sides and pink belly. On an average, they are known to attain a length of 10 feet, which makes them one of the smallest among the different types of whales on the planet. Though rare, individuals measuring around 14 feet have also been recorded.
Even though the lower jaw of pygmy sperm whales is very small compared to their upper jaw, all the teeth―usually ranging between 20 - 32―are located in it.
Habitat and Geographical Distribution
The rare creatures that these whales are, it is very difficult to map their geographical distribution across the world. They are most often seen in off-shore temperate waters of the Atlantic and Pacific Oceans. Even though rare sightings in tropical and subtropical waters have been recorded, they are not sufficient to claim that their range is so vast.
While migration is a natural phenomenon in most of the whales, there is no evidence of migration in this species.
Diet and Hunting
It is very difficult to determine the dietary habits or hunting abilities of any species which is so rare. In the course of study of washed-up specimen, researchers found carapaces and appendages of certain marine animals in their stomach.
Based on these studies, they deduced that these whales most often feed on small marine organisms, including crabs, shrimp, squids, octopi, and various other species of fish that are relatively small in size.
With so little information available, it is very difficult to come to any specific conclusion about the behavior of this species. We don't even know how many pygmy sperm whales are there in the wild, and without that we can't decide what the conservation status for this species should be.