Wellington, Nov 6 (IANS): The world's rarest whale species - the spade-toothed beaked whale has been spotted for the first time by scientists of New Zealand in the Pacific Ocean.

"This is the first time a spade-toothed beaked whale has been seen as a complete specimen, and we were lucky enough to find two of them," says Rochelle Constantine, from the University of Auckland, who led the study.

"It's incredible to think that, until recently, such a large animal was concealed in the South Pacific Ocean and shows how little we know about ocean bio-diversity," adds Constantine, the journal Current Biology reports.

The scientists used DNA evidence to prove that a mother and her male calf which stranded in New Zealand in late 2010 were the first animals of their kind ever seen, according to an Auckland statement.

Since the two animals are the only intact members of their species sighted, the spade-toothed beaked whale is the world's rarest whale. Until now the only evidence for the species' existence came from three skull and jaw fragments found around New Zealand and Robinson Crusoe Island, Chile.

The spade-toothed beaked whale was discovered on Pitt Island in the Chatham Islands in 1872, but it wasn't until 2002 that scientists from The University of Auckland analysed DNA from the three skull fragments, recovered from museum archives, and realised that their genetic profiles were the same and did not correspond to any other known species.

On Dec 31, 2010, a female whale (5.3 metres) and male calf (3.5 metres) stranded and later died on Opape Beach in the Bay of Plenty, New Zealand. After death they were measured, photographed and tissue samples were taken by the Department of Conservation.

"This is a real New Zealand story - its all linked here, from the discovery of two of the bone fragments to the identification of the species and now the first sighting of the whales," says Constantine.