The world's rarest whale has been seen for the first time, after a mother and her male calf were stranded and died on a New Zealand beach.
The spade-toothed beaked whale, Mesoplodon traversii, was previously known only from a few bones, and scientists had suspected it was extinct.
"This is the first time this species - a whale over five meters in length - has ever been seen as a complete specimen, and we were lucky enough to find two of them," says Rochelle Constantine of the University of Auckland.
"Up until now, all we have known about the spade-toothed beaked whale was from three partial skulls collected from New Zealand and Chile over a 140-year period. It is remarkable that we know almost nothing about such a large mammal."
The two whales were discovered in December 2010, when they became stranded and subsequently died on Opape Beach. The New Zealand Department of Conservation was able to photograph the animals and collect measurements and tissue samples.
At first, the whales were assumed not to be spade-toothed beaked whales, but rather the much more common Gray's beaked whales. But a routine DNA analysis revealed the truth.
"When these specimens came to our lab, we extracted the DNA as we usually do for samples like these, and we were very surprised to find that they were spade-toothed beaked whales," says Constantine. "We ran the samples a few times to make sure before we told everyone."
The researchers say they have no idea why the whales have never been spotted before.
"It may be that they are simply an offshore species that lives and dies in the deep ocean waters and only rarely wash ashore," says Constantine. "New Zealand is surrounded by massive oceans. There is a lot of marine life that remains unknown to us."