For more than a decade, an unidentified collection of bizarre shark eggs has puzzled Australian scientists – but now they’ve discovered the eggs belong to a new species of demon catshark.
White et al./Journal of Fish BiologyThe new species of demon catshark is distinguished by its distinctive bright white eyes.
An unidentified shark egg discovered off Australia’s Kimberley coast in 2011 has recently helped researchers identify a new species of demon cat shark. The newly discovered shark has distinctive white eyes that scientists say are rare for deep-sea sharks – and could offer a better understanding of shark evolution.
According to a report by the Australian Broadcasting Company (ABC), finding the identity of the catshark demon (Apristurus ovicorrugatu) has been particularly time-consuming and frustrating for scientists at Australia’s Commonwealth Scientific and Industrial Research Organization (CSIRO).
“It’s interesting because we often have the idea that something might be a new species, but it can take a long time to resolve and compare with other species,” said Will White, senior curator of the Collection. CSIRO Australian National Fish Market.
Part of the difficulty, White said, was that the researchers didn’t have an actual animal to work with. Instead, they had a small collection of unidentified shark eggs found in 1989 and a similar egg found in 2011 by researcher Brett Human, then a volunteer at the Western Australia Museum.
The eggs were noticeably different from most shark eggs, with strong T-shaped ridges only found in another species of shark, although it is unique among egg-laying sharks in Australia.
The man found the unique egg and linked it to the 1989 collection, but he could only identify them as belonging to the genus Apriture. He was unable to determine their species.
White et al./Journal of Fish BiologyThe T-shaped ridges covering the Demon Catshark eggs.
“The egg crates had very distinctive longitudinal ridges on their surfaces that were T-shaped in cross-section,” White said. Live Science. “Only one other species in the world has been found to have egg cases with this crest shape and it is an entirely different genus.”
White described the journey to identify the new species as “frustrating.” But he and his colleagues made a major breakthrough by combing through the archives of the Australian National Fish Collection – a similar document apriture specimen found in the same region as the eggs had been misidentified as a South China catshark (Aprsiturus sinensis).
It was female and happened to be carrying an egg carton that matched those found in 2011.
“Fortunately, the female specimen we found contained an identically ridged egg box and confirmed our suspicions,” White said.
And in another stroke of luck, the female was pregnant, and researchers found a late-term embryo inside one of the egg cases.
White et al./Journal of Fish BiologyThe late embryo found in one of the egg cases observed by White and his colleagues.
With the mystery of the egg carton solved and Apristurus ovicorrugatus identified, researchers were finally able to piece together a more complete understanding of this demon catshark.
Demon or ghost cat sharks are one of the most diverse genera of sharks in the world, with about 40 known species, but A. ovicorrugatus is particularly unique because of her bright white eyes.
“Normally, [demon catsharks’ eyes are] always very dark – either dark green eyes or just black eyes,” White said. White irises have only been found in another species of deep-sea shark, Apristurus nakayai from New Caledonia and Papua New Guinea.
“It must have evolved for a particular reason, not just within a species, but within a group of species,” he said.
White et al./Journal of Fish BiologyA close up of the white irises unique to the recently discovered species of demon catshark.
“It definitely opened up research questions about a different evolutionary pathway that we hadn’t considered in this group,” White added.
This new species of demon catshark was found in water more than 2,300 feet deep where it had laid its eggs on coral. As White explained, these sharks are not often seen due to the depth at which they are found.
“If you look at this coastline, where it’s usually quite steep and drops off quickly, it has a relatively narrow depth distribution,” he said. “They probably follow a habitat where they lay their eggs on a particular species of coral.”
A similar but distinct species of catshark had previously been found on the other side of the country, just off the Gold Coast. White said the new discovery helped his team establish a link between the two species.
“We know very little about deep-sea fauna in Australia,” he said, expressing hope that more discoveries will be made in the years to come.
“As more deep-sea surveys continue, I expect we will uncover more species records – there is still much to come.”
After discovering this newly discovered species of shark, learn about the world’s scariest sea creatures. Then check out these 28 mind-blowing facts about sharks.
