Around the Pier: Churro-Like Marine Worm Discovered by Scripps Scientists Is One of the 'Top 10 Species of 2017'

A marine worm discovered by researchers at Scripps Institution of Oceanography at the University of California San Diego and named for a tasty confection is one of the Top 10 New Species for 2017. 

Xenoturbella churro joins a spider and an ant whose names are drawn from references in popular modern-day literature, a brilliant pink katydid and an omnivorous rat among the top discoveries identified by the State University of New York College of Environmental Science and Forestry (ESF). This is the 10^th year ESF's International Institute for Species Exploration (IISE) has compiled the list.

What’s special about this worm? Its standout feature is that it looks a lot like a churro, the fried pastry dusted with cinnamon and sugar popular in Spain, Latin America, and at Costco food courts everywhere. It looks so much like a churro that Greg Rouse, the Scripps biologist who discovered it, decided it should be named after the dessert item.

The full name of the worm is Xenoturbella churro, and it was one of four new Xenoturbella species identified by a team that included Rouse as well as scientists from the Western Australia Museum and the Monterey Bay Aquarium Research Institute. The other three species were named with more standard descriptors: Xenoturbella monstrosa was named for its large size, Xenoturbella profunda for the great depth at which it was discovered, and Xenoturbella hollandorum was named in honor of Scripps biologists Linda and Nick Holland for their contributions to evolutionary biology.

But the fourth species was just kind of odd. “I was trying to think of the name for it,” Rouse recalled, when Jose Carvajal, one of his staff, saw a video of the worm and casually remarked, “Wow, that looks like a churro!”

“We were like well, why not name it after the churro?” Rouse said. The species had been discovered off the coast of Mexico in the Gulf of California and it seemed appropriate.

X. churro is a 10-centimeter- (four-inch) long marine worm, one of half a dozen species now known in the genus. It is representative of a group of primitive worm-like animals that are the earliest branch in the family tree of bilaterally symmetrical animals, including insects and humans. Like some of its relatives, X. churro is believed to feed upon mollusks such as clams. The new species is uniformly orange-pink in color with four deep longitudinal furrows—just like a churro.

This is the second year in a row that a species discovered by Scripps researchers has landed in the IISE top 10.  In 2016, the Ruby Seadragon (Phyllopteryx dewysea) discovered by Rouse, Scripps graduate student Josefin Stiller, and colleague Nerida Wilson of the Western Australian Museum, made the list.

The institute's international committee of taxonomists selects the top 10 species from among the approximately 18,000 new species named the previous year. The list is made public around May 23 to recognize the birthday of Carolus Linnaeus, an 18th century Swedish botanist who is considered the father of modern taxonomy.

“During the decade since our first Top 10 list, nearly 200,000 new species have been discovered and named. This would be nothing but good news were it not for the biodiversity crisis and the fact that we’re losing species faster than we’re discovering them,” said ESF President Quentin Wheeler, who is founding director of the IISE. “The rate of extinction is 1,000 times faster than in prehistory. Unless we accelerate species exploration we risk never knowing millions of species or learning the amazing and useful things they can teach us.”

Rouse, whose work on X. churro has been supported by the National Science Foundation Assembling the Tree of Life program under grant number DEB1036368, says he hopes celebrating new species like X. churro will help remind people that there are a lot of species in the world waiting to be found.

 “A lot of people think we’ve already discovered everything, but we’ve only discovered a small minority,” he says. “There’s so much more to do, and there’s so much wonderful diversity.”

– Mallory Pickett

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