A boatload of tourists got to witness nature at its most brutal when a killer whale flicked a pseudo orca high into the air, broke its back and ate both it and its calf in the Bay of Islands yesterday.

The attack occurred at the Black Rocks, about four nautical miles from Paihia, after a pod of eight killer whales chased more than a dozen pseudo orcas.

As its name suggests, the pseudo orca shares characteristics with the real orca (or "killer whale") in that it has a similar look and the same deadly nature.

Explore Images director Rob Hunt, whose photographers captured the killing from aboard a Dolphin Discoveries boat, said it was a "one in a million" viewing.

He said the boat was just 50 to 100m away while the killing occurred, as the other orcas fled. Mr Hunt said markings showed it was a female killer whale that chased the orca for several minutes, playing with it and flicking it 10 metres into the air, before breaking the orca's back on her nose.

He said scientists who saw the photographs said they had never seen anything like it.