A new species of scaly fish has been found, but its discovery is an obstacle in the search for a new genus or species.
The scaly fish discovered in New Zealand, called the Tree-cunning Geuragai, seems to have been trapped in a rock-shaped cavity. Scientists believe that a younger, now mature Geuragai population was already living in the trap, which was first discovered in 2016, when another geological anomaly was found in the scaly fish’s habitat in the lowlands near New Zealand’s South Island.
The new species is actually one of five “tree-cunning” geuragai that have been discovered in New Zealand since 2012. Previously, geuragai – a filter-feeding fish found in the waters between Victoria and Wellington – were found as “fringeless,” meaning they are not evenly distributed across the island’s landscape.
A previous acoustic survey led the researchers to a small, cone-shaped cavity just west of the geuragai’s range in the coastal area of Whanganui, New Zealand. Using a microphone, they listened for calls coming from within the mouth of the cavity, and an alarm was sounded when no sounds were made. Later, they picked up sound proof images of the mouth.
“Being underwater may have provided some physiological protection for the trapped fish because it avoided the ocean surface for up to 10 hours,” associate professor Brad Christopher, of the University of Otago, New Zealand, said in a press release. “Listening for sound in the opening also preserved the acoustic environment by recording the sound before the fish went deeper into the environment.”
After a five-year search, a DNA analysis discovered that the geuragai trapped within the cavity belonged to the family Gaedae, a type of filter feeder with long, thin-spined cartilage teeth.
“The discovery that Gaedae were trapped in a single original trap,” said biophysicist Robyn Jacobs, of the Department of Molecular Biophysics and Biochemistry at the University of Melbourne, “is likely to present challenges for future studies as more are likely to be trapped in new cavities or tangle springs.”
The researchers were able to communicate with two of the five captured fish, and to release two of them from the cave. When they captured the other two, the location of the trap was revealed in their recovery efforts.
The scaly fish were named after a few of the geuragai residents, as Gaedae are sailors in the Inuit language of New Zealand. The three are part of a broader orcaetus, which means “tree dwelling.” The scaly fish were found living in both shallow and deep water, which shows that they are perfectly adapted to the westerly and northeast currents that make up the Pacific Coast of New Zealand.
“This discovery is remarkable as we are still very much discovering new species in deep oceans,” said senior author Patrick Davies, of the University of Otago, New Zealand. “It is surprising that the presence of tangle springs, previously thought to be only in shallow water, has been found to be widespread throughout this deep ocean region.”
The latest genetic analysis has revealed that the geuragai trap holds a few other fish and other kinds of tangle springs. The trap has also yielded fossilized sea slugs that could be half a million years old.
“This discovery is wonderful news for the geuragai, their unique genus and their fish community,” Davies said in a press release. “It opens up new research directions that are likely to reveal more about their ecology, ecology of their tanks, spawning behavior and migration from ponds and lagoons to open waters for potential prey and services, further adding to their diversity.”