The deep sea is filled with all manner of strange and unusual creatures, and as we’ve only explored around 2% of the ocean, bizarre new species are discovered all the time. The newest of these surreal sea creatures? A demon catshark with glowing white eyes.
The shark, dubbed Apristurus ovicorrugatus, has swum under the radar for over a decade. Scientists found evidence of its existence back in 2011, thanks to the recovery of an unfamiliar mermaid’s purse (shark egg case). It would be another 12 years, though, before they found the species responsible for laying it.
The long-awaited discovery finally arrived when they spotted a new species of demon catshark off the coast of Australia.
Like its relatives, the new bottom feeder had elongated cat-like eyes. To scientists’ surprise, however, the animal’s eyes were pure white. Even for a creature as odd as a deepwater shark, white irises are a rarity.
A new demon catshark species, characterised by its glowing white eyes and living more than 400 metres below the surface, has been discovered off the coast of northern WA. #9News pic.twitter.com/ib5p6tJvZb— 9News Perth (@9NewsPerth) May 10, 2023
“Normally, they’re always very dark — either dark green or just black eyes,” Will White, senior curator of the CSIRO’s Australian National Fish Collection, explained to ABC.
“It has been found only in one other deepwater shark species — a member of a closely related species from New Caledonia and Papua New Guinea.”
As White explained, the unusual characteristic could help scientists learn more about the links between similar species.
“It must have evolved for some particular reason, not just within one species, but within a group of species,” he said. “It has definitely opened up research questions about a different evolutionary pathway that we hadn’t considered within this group.”
Declaring a newly discovered species takes time
When researcher Brett Human discovered a shark egg while volunteering at the WA Museum back in 2011, he found himself perplexed. The egg resembled that of another shark species but wasn’t an exact match – so what kind of shark did it belong to?
A deep dive into shark eggs led him to the genus Apristurus, commonly known as the ghost or demon catsharks. The species, however, still eluded him.
All signs pointed to a new species, but the last thing you want to do as a scientist is jump to conclusions and be wrong. No one needed another “incredible goblin shark was actually just a plastic toy” fiasco on their hands.
“It’s interesting, because we often get an idea that something might be a new species, but it can take a long time for us to resolve and compare with other species,” White said.
“We very quickly worked out that those cases don’t match any other species that belong to that genus in Australia. [It was] frustrating, because we didn’t have an actual animal to work with.”
Eventually, researchers were able to say without a doubt that the egg belonged to a new species. There was just one problem: demon catsharks make their homes thousands of feet beneath the surface. Finding a specimen wasn’t going to be an easy task.
Researchers had the answers to the new demon catshark all along
As it turns out, researchers didn’t need to scour the depths for a specimen of the new demon catshark. An A. ovicorrugatus had been found and archived years before but misidentified as a known species.
The egg case recovered in 2011 held the answers, after all. Just as scientists guessed, it was discovered at a depth of around 1,600 feet. After matching it with the misidentified catshark specimen, a pregnant female found at a mind-boggling 2,300 feet, they solved the puzzle.
“We don’t see a lot of them because of the depth they occur,” White said. “They have a relatively narrow depth distribution. They’re probably following a habitat in which they lay their eggs on a particular coral species.”
The identification of the demon catshark has already unlocked answers about other species, and scientists hope it’s just the beginning for deepwater discovery.
“We actually uncovered a similar species off the Gold Coast, which is closely related but a very distinct species,” he said. “We just know very little about deepwater fauna in Australia.”
“As more deepwater surveys continue, I think we’ll uncover more species records. There’s still a lot to come.”