07 May 2010

"City of Gonads" Jellyfish Discovered

Unique among jellyfishes, a newly described jellyfish has its gonads on the outside, like "skyscrapers in a downtown business district"
Csiromedusa medeopolis, the new "city of gonads" jellyfish species. Photograph courtesy Lisa-ann Gershwin, courtesy Zootaxa/Queen Victoria Museum and Art Gallery

Gonads=sexual organs. What good are external gonads to a jellyfish? "I've thought about this for so long—I have no idea," said Lisa-Ann Gershwin who made the discovery. "There may be some functional reason, but I can't see what it is."

"City of Gonads" Jellyfish Discovered
The new species, C. medeopolis, keeps the family jewels on display.
Carolyn Barry, National Geographic News 6 May 10;

Sporting a reproductive "skyline," a new species of jellyfish is like nothing else known under the sea, a new study says.

Shaped like flying saucers, both males and females of the new jellyfish have gonads on the outsides of their bodies, unlike any of the approximately 3,000 other jellyfish species known to science­.

Gonads are the reproductive glands that produce sperm in males and eggs in females.

Arranged in a ring atop the jellyfish, the gonads, upon close inspection, resemble "skyscrapers in a downtown business district," said Lisa-Ann Gershwin, curator of zoology at the Queen Victoria Museum and Art Gallery in Launceston, Australia.

Accordingly, Gershwin gave the jellyfish the species name "medeopolis," Latin for "city of gonads."

"It's just so completely different from anything we've ever seen before," Gershwin said—in fact, the jellyfish has forced the creation of a whole new family and genus, Csiromedusidae and Csiromedusa, respectively.

Both names honor the Australian government's Commonwealth Scientific and Industrial Research Organization (CSIRO), which assisted the scientists with their research.

"City of Gonads" Stumps Scientist

Gershwin and colleagues discovered the city-of-gonads jellyfish eight years ago in a part-seawater river in the city of Hobart (map) on the Australian island of Tasmania. It took until now, though, for the scientists to verify that Csiromedusa medeopolis represents a new family.

Harmless to humans, the new jellyfish species measures just 1.5 to 2 millimeters (0.06 to 0.08 inch) across—"not the smallest ever known, but it would be pretty close," Gershwin said.

About 90 percent of jellyfish species are smaller than an inch (2.5 centimeters), but fewer than 0.5 percent of jellyfish are measured in millimeters.

Making the Csiromedusa medeopolis discovery was "like a day at Disneyland for a scientist," said Gershwin, who's named more than 160 new jellyfish species, including a "rainbow glow" jelly.
Despite all that experience, she's at a loss to explain what good external gonads would be for a jellyfish.

"I've thought about this for so long—I have no idea," Gershwin said. "There may be some functional reason, but I can't see what it is."

The city-of-gonads jellyfish study is published online this week in the journal Zootaxa.


Experts astounded by 'city of gonads' jellyfish
ABC Net 6 May 10;

Tasmanian scientists have discovered a new species of jellyfish in Hobart's River Derwent and given it a sexy name.

The species is only a few millimetres wide and scientists say it looks like a flying saucer with a cluster of gonads, or sex organs, on top.

Scientists discovered the jellyfish while surveying the waters outside the CSIRO in Hobart.

The new species has been named Csiromedusa medeopolis, meaning "jellyfish from CSIRO" and "city of gonads".

Launceston jellyfish expert Lisa-Ann Gershwin says it is an astounding discovery.

"It's absolutely different from every other jellyfish that's ever been known," Dr Gershwin said.

"So we not only put it into its own new species and its own new genus, but it's actually a brand new family."

Dr Gershwin says the find is also tremendously exciting.

"Quite possibly and quite humbly the greatest discovery of my career, ever. I mean I'll be lucky if I ever get a discovery even half as incredible again," she said.

"You know any mum with a new bub is always excited, but when you have a whole family of new bubs I think it's triply exciting."

Dr Gershwin says the jellyfish is harmless to humans.

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