How belittling to call a whole species “false”—yet that is how the false killer whale is known. Such a derogatory name has a simple explanation, and it lies with the skull of this little-studied species. Externally they bear little, if any, resemblance to “killer whales”. They do not have the distinctive black and white coloration, nor the robust body shape. Instead, they are shades of dark to light grey, with a rather pronounced “underslung” lower jaw, which gives them a perpetual visage of good humour. Internally, however, their skulls are very similar to orca and they too have 38–40 teeth equipped for effectively capturing prey.

Their scientific name, Pseudorca crassidens, gives rise to their common name, as Pseud (silent P, so pronounced sood) is derived from the Greek word for false or counterfeit. Combining this with orca gives us their common moniker; however, anyone in the know calls them Pseudorca. They are the only member of this genus and their species name, crassidens, is derived from the Latin for thick-tooth.

They were first discovered by Europeans as a fossil on land in England, in 1846, and thought to be extinct. But within 20 years, the fossil evidence came to life when 100 individuals beached themselves on the coast of Germany. Pseudorca are intensely social and mass strandings have continued to occur around the world, with New Zealand being no exception—230 stranded at Manukau, Auckland, in 1978. Yet it wasn’t until the late 1950s that observations at sea were collated and behavioural records were published scientifically, although they are still considered one of the least understood of the dolphins. And, yes, again, their common name is a misnomer as they are not true whales but rather one of the larger members of the dolphin family.

Pseudorca are generally found in tropical to warm-temperate waters and were first recorded in our waters by James Hector in 1872. However, their distribution is constantly being refined, with new records expanding their known range to now include waters with a wide temperature range of 9–30° C. Off Northland, where most New Zealand sightings occur, Pseudorca are typically seen between December and April. Although considered pelagic (an open-ocean species), they are occasionally sighted closer to shore. But regardless of where they are found, remarkably little is known about them.

We have hints about their food preferences from looking at stomach contents collected from strandings and have found that their diet consists predominantly of squid and fish. Like orca, they are known to take dolphins and have also been observed attacking humpback and sperm whales. The Pseudorca, rather than attempting to kill these larger whales, may be intending only to remove mouthfuls or intimidate their larger cousins. Another theory has it that the Pseudorca are harassing these bigger species to the point of vomiting, then feeding on the regurgitations.