Two whales of a species that has never been seen alive for 140 years were found washed up on Opape Beach in New Zealand.

The spade-toothed beaked whales (Mesoplodon traversii) were found in December, 2010. Beach visitors alerted the New Zealand Department of Conservation who then collected tissue samples and photographed the whales.

One of the whales (female) was about 5.3 meters long while the other was a male calf 3.5-metre-long, according to Discover Magazine.

The spade-toothed beaked whale was discovered on Pitt Island in the Chatham Islands in 1872 but it was only in 2002 when researchers analyzed the specimen's DNA and compared it with other skull fragments of the whale species. Until the discovery of the stranded whales, researchers weren't sure if this species of whales still existed.

"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. 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," said Rochelle Constantine from the University of Auckland.

Authorities earlier thought that the whales were Gray's beaked whales - a more common type of whale. It was only after they analyzed the DNA of the whales that they knew they are looking at a species of whale that hasn't been seen since 1872.

"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. We ran the samples a few times to make sure before we told everyone," said Constantine.

There are some 21 species of beaked whales in the world and very little is known about them. They are thought to be deep-sea divers that rarely come near a shore. Although adult males of the species might be identified based on morphology, identifying females and younger males of the species is difficult as they look alike.

"It may be that they are simply an offshore species that lives and dies in the deep ocean waters and only rarely wash ashore. New Zealand is surrounded by massive oceans. There is a lot of marine life that remains unknown to us," said Constantine.

The study is published in the journalĀ Current Biology.