World's rarest whale spotted - twice

SMALL PRINTS: Here's one for the pub quiz. What's the rarest whale in the world? The spade-toothed beaked whale (Mesoplodon traversii) is a pretty good contender.

When two of the animals washed up on Opape Beach in New Zealand in late December 2010, and unfortunately died, they were initially misidentified as Gray’s beaked whales.

The mistake is hardly surprising though, because spade-toothed beaked whales don’t exactly turn up frequently.

Bone fragments from the whale species have been found previously – in the Chatham Islands, New Zealand in 1872, on White Island, New Zealand in the 1950s, and on Robinson Crusoe Island off the coast of Chile in 1986, according to a study in Current Biology.

For the whales found in 2010, the paper’s authors did a bit of scientific sleuthing and looked at mitochondrial DNA.

“There is a conserved region on the maternally inherited mitochondrial DNA that we can use to identify cetacean species,” explains researcher Dr Rochelle Constantine from the University of Auckland, who is currently on sabbatical at Lund University in Sweden.

She and colleague Kirsten Thompson were “quite surprised to say the least” when the evidence pointed to the animals being spade-toothed beaked whales. These were the first entire specimens on record.

They re-ran the sample again and sent it to co-author Scott Baker for confirmation. “Although it was very clear that they were spade-toothed beaked whales, we wanted to make sure before we told others,” she says.

The fact that such a large species can go concealed in the South Pacific Ocean highlights how little we know about ocean biodiversity, she adds. “There are so many marine organisms, large and small, that we know nothing about.”