Scientists dissect ‘world’s rarest whale’ for clues on little-known species

A spade-tooth whale – thought to be the world’s rarest whale species – is undergoing dissection in New Zealand, in the first ever examination of a complete specimen.

Spade-toothed whales are a type of beaked whale named for their teeth resembling the spade-like “flensing” blade once used to strip whales of their blubber. Just seven have been documented since the 1800s, with all but one found in New Zealand.

The five metre-long male whale washed ashore in Otago, in the South Island in July, prompting excitement from cetacean specialists whose knowledge of the creatures had relied entirely on a series of bones and tissue discovered from those specimens found decades apart.

International and local scientists assembled on Monday, alongside local Māori , to begin an examination of the whale at the Invermay Agresearch Centre in Mosgiel, a city outside Dunedin.

The atmosphere inside the centre has been one of “reverence” for the animal, said Anton van Helden, a science adviser at the department of conservation and a global expert on the spade-toothed whale.

“We’re working around a dead animal, but it’s telling us about how it [lived], and also that’s unpacking all of the life stories of the people involved around it,” he said.

Van Helden, the lead author on a paper that gave the species its name, said the opportunity to examine the whale is “an incredible moment”.

“Beaked whales are the most enigmatic group of large mammals on the planet, they are deep divers that are rarely seen at sea.”

“This one is the rarest of the rare, only the seventh specimen known from anywhere in the world, and the first opportunity we have had to undertake a dissection like this,” he said.

The first example of a spade-toothed whale was found in 1874, when the species was described based on a lower jaw bone and two teeth found in the Chatham Islands, off the east coast of New Zealand’s South Island. DNA taken from the tissue of two buried specimens, a mother and calf, in 2010 allowed scientists to describe what it looked like. In 2017, another specimen was beached very remotely in Waipiro Bay, north of Gisborne, and buried before being dissected.

In a 2012 study on the spade-toothed whale, published in Current Biology, scientists note that several species of beaked whale live in the South Pacific Ocean, which has some of the world’s deepest ocean trenches. The cetaceans are believed to be “exceptionally deep divers” the study said, spending their time far below the surface hunting squid and small fish.

The examination of the whale is expected to take five days. Researchers are primarily concerned with describing the species and understanding how it lives.

They will be methodically looking at the whale’s stomach layout (which is different in every species of beaked whale), how it creates sound, how many vertebrae it has, its blubber weight, its throat structure and more – the findings of which could also inform how human threats to the species are managed.

Scientists are working with local Māori from Ōtākou, who have customary rights over the area where the whale washed up. Māori consider whales a taonga – sacred treasure of cultural significance – said Tūmai Cassidy, who is contributing to the study.

“Whales are incredibly important animals in our culture … our arrival to Aotearoa [New Zealand] is deeply tied to whales and like other cultures around the world we utilise different parts of their bodies.”

Cassidy said Māori from Ōtākou have been closely involved in the process since the whale washed ashore, and the opportunity to offer Indigenous knowledge and collaborate with western science is a “epic privilege and huge opportunity.”

When complete, Ōtākou Māori will give the whale’s skeleton to the Otago Museum but will hold the jawbone for cultural purposes.