A new species of giant ocean sunfish has been discovered, the heaviest type of bony fish that can weigh over two tonnes and grow to three metres long.
The new species discovered by an Australian researcher has been named the hoodwinker (mola tecta).
Marianne Nyegaard, from Murdoch University in Perth, found the species while researching sunfish in the Indo-Pacific region as part of her PhD.
The species prefers cold water, and has so far been found around New Zealand, around the southeast coast of Australia, off Africa and southern Chile.
The latin name for the species is Mola tecta from the Latin tectus meaning 'disguised' or 'hidden', because the species has gone undiscovered for so long.
Ms Nyegaard began investigating after noticing genetic differences in sunfish samples from Australian and New Zealand longline fishery.
"A Japanese research group first found genetic evidence of an unknown sunfish species in Australian waters 10 years ago, but the fish kept eluding the scientific community because we didn't know what it looked like," she said.
"Finding these fish and storing specimens for studies is a logistical nightmare due to their elusive nature and enormous size, so sunfish research is difficult at the best of times."
Over a three-year period she collected data from 27 specimens, travelling thousands of kilometres and relying on strangers to take samples of sunfish from remote beaches.
"The new species managed to evade discovery for nearly three centuries by 'hiding' in a messy history of sunfish taxonomy, partially because they are so difficult to preserve and study, even for natural history museums," Ms Nyegaard said.
Ms Nyegaard believes that the species feeds during deep dives, because their digestive tracts mostly contain salps - a deep sea creature loosely similar to a jellyfish.
The research was collaborative effort between Murdoch University, the Museum of New Zealand Te Papa Tongarewa, the University of Otago, Hiroshima University and the University of Tokyo.