A scarcely-known and little-seen hourglass dolphin has washed up in Southland, only the third to be discovered in New Zealand in around 150 years.
The dolphin is estimated to be an adult male, based on its size.
Massey University associate professor Karen Stockin, who will be carrying out the necropsy in Auckland, says the stranding will mean huge developments for science.
"We know very little about them at all. It's a privilege but also a sad privilege when you get to examine one post-mortem," she told 1 NEWS today.
"Nationally, it's very significant because it's not a species that we typically see on a regular basis in New Zealand.
"And secondly, even on a global status, it's really important just because, again, so few specimens ever strand that there are very few case studies around their biology, anatomy, or really anything about them."
It's only the third hourglass dolphin to have been discovered on New Zealand's coastlines on record. The last was in 2010, Dr Stockin says.
Dr Stockin believes this dolphin was only dead for around 12 hours before being reported to the Department of Conservation on Wednesday.
She says it's too early to speculate on the cause of death.
A detailed CT scan has been taken of the hourglass dolphin in Invercargill so far, before the body is transported to Auckland for the post-mortem.
Part of that will include seeing if it's eaten microplastics - tiny portions of plastic - and any other contaminants, as part of the routine screening.
Dr Stockin says the dead dolphin will be a "significant contribution to science" worldwide.
"They're such a rarely and poorly described species that this information does not exist in scientific literature presently," she says.
"It really does highlight the importance of ongoing stranding monitoring, not just in New Zealand but globally."
Hourglass dolphins usually live in the freezing sub-Antarctic waters, deep in the Southern Ocean.
"It's not typical unless you're working those really rough terrain of the southern waters to come across them," Dr Stockin says.
"So they're quite enigmatic and really poorly known."
The local iwi has been alerted and gave permission for the dolphin to be taken to Auckland for the post-mortem.
Once the research is done, it'll be passed on to the iwi and the Department of Conservation before being published worldwide.