A spade-toothed beaked whale, the world's rarest species of whale, has been seen for the first time in New Zealand.
Scientists have confirmed that two whales which died after being stranded in 2010 were in fact members of the reclusive species. They are the only two specicmens ever to be sighted.
Prior to them surfacing in New Zealand, skull and jaw fragments were researchers' sole proof of the spade-toothed beaked whale's existence. These fragments were found around New Zealand and the Robinson Crusoe Island, off the coast of Chile.
Lead scientist Rochelle Constantine said: "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
"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 biodiversity."
'Power of DNA'
When the two whales - measuring 5.3m and 3.5m - turned up on the Opape Beach in the Bay of Plenty on 31 December 2010, scientists measured and photographed the animals and looked at tissue samples.
They were initially thought to be the most common beaked whale in New Zealand, the Gray's beaked whale. However, having consulted DNA samples, researchers have now confirmed they are the world's rarest whale.
Constantine said: "This discovery is a real reward for that work. It demonstrates the value of archival collections and the power of DNA as a forensic tool.
"This is a real New Zealand story - it's 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."
The spade-toothed whale was first discovered on the Pitt Island in the Chatham Archipelago in 1872. However its existence was not confirmed until 2002, when DNA of skull fragments was analysed.
It lives in the South Pacific Ocean, which spans around 85 million sq km. Beaked whales are believed to be exceptionally deep divers, as they forage for squid and small fish, spending little time at the surface of the sea.
Features identified on the spade-toothed beaked whale include dark eye patches, a white belly and dark flippers.
The research on the two specimens is published in Current Biology.