Wolverine and blind eel among 212 new freshwater species | Fish

Scientists are celebrating 212 “new” species of freshwater fish, including a blind eel found in the grounds of a school for blind children and a fish named Wolverine that is armed with a hidden weapons system.

the 2021 New Species Reportpublished by the conservation organization Shoal, shows how diverse and remarkable the world’s often undervalued freshwater species are, and suggests that there is still plenty of life to be discovered in lakes, rivers and wetlands of the world.

“It’s fascinating that over 200 new species of freshwater fish can be described in a single year,” said Harmony Patricio, Shoal’s conservation program manager. “You might see this level of new discoveries for organisms like plants or insects, but not really for vertebrates.

“That means there are still hundreds and hundreds of freshwater fish in the world that scientists don’t yet know about,” she said. “Furthermore, many newly described species have quite unique and unexpected traits.”

the Wolverine Hopliancistrus, whose hidden spikes inspired researchers to name it after the X-Men character. Photo: Juan Marcos Mirande, Fundacion Miguel Lillo/Courtesy of PLoS One

One of these unexpected physical traits is the Wolverine pleco’s hidden weapon system (Wolverine Hopliancistrus), earning him an X-Men inspired name. “This species has strong lateral curved spikes called odontodes hidden under the gill covers that can be extended to sting anything that tries to disturb them,” Patricio said.

“Other related species in the same family, even those with large spines, are not known to exhibit such behavior. Researchers who described this species ended up with quite a few finger injuries when collecting specimens in nature.

On average, four freshwater fish species per week were newly described last year. Other finds include the bright red Mumbai blind eel (Rakthamichthys mumba), which has no fins, scales or eyes, and was found at the bottom of a well in the grounds of a school for blind children; the tiny, translucent Danielle brain, discovered in southern Myanmar and barely larger than a thumbnail; and the colorful Kijimuna and Bunagaya gobies (Kijimuna lentils and Bunagaya with lentilslisten)) in southern Japan, named after wood spirits in Okinawan folklore.

Each of the 212 discoveries offers new opportunities for scientists to increase their understanding of freshwater species, including their anatomy, evolution, and the connections between other creatures and their habitats.

A male Lentipes kijimuna, named after an Okinawan woodland sprite.
A male Kijimuna lentilsnamed after an Okinawa woodland sprite. Photography: Ken Maeda/Courtesy of Shoal

The male Danionella’s Brain, for example, has sparked researchers’ curiosity about its ability to make a drumming sound, most likely by tapping a thin strip of cartilage on its swim bladder, like a drumstick – a relatively complex and unusual form of communication for a si little creature. The same species has no roof over its skull – its brain cavity is covered only by a thin layer of skin – allowing scientists to study brain activity associated with function without harming the fish.

There are at least 18,267 species of freshwater fish, according to the standard reference work, Catalog of Eschmeyer’s Fishes. But the overall freshwater situation is worrying. According to the World’s Forgotten Fishes report, which Shoal, WWF and other partners published in 2021, more than a third of freshwater fish species are threatened with extinction, despite their importance for biodiversity and as a source food for billions of people.

“We know that 80 species of freshwater fish are extinct in modern times, whereas there are usually around 150 to 200 or more new species discovered in an average year,” Patricio said. “But the population levels of many freshwater fish have declined dramatically over the past 50+ years.

A male Danionella brain.  The species makes a drum sound and has no roof over its skull.
A male Danionella’s Brain. The species makes a drum sound and has no roof over its skull. Photography: Ralf Britz/Courtesy of Shoal

“There are a whole host of factors that have led to their decline, but the main causes are the impacts of invasive species, pollution, overfishing and habitat loss and degradation.”

More work is needed to protect lakes, rivers and other freshwater sources, and their inhabitants, including many other “new” species waiting to be discovered. Shoal hopes its inaugural new species report will raise awareness “of the freshwater biodiversity crisis we face,” Patricio said, “so that people realize that freshwater fish are disappearing twice as fast. as marine or terrestrial species.

“I hope,” she said, “that they will be motivated to support conservation efforts and encourage their governments to do more.”

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Earnest A. Martinez