Mysterious Mushroom-Shaped Deep-Sea Creatures Found off Australia

Mysterious animals discovered offshore Australia resemble floppy chanterelle mushrooms but feel like dollops of gelatin, according to a new study.

The ocean-dwelling creatures are so unusual that an entire new taxonomic family was created to classify them, scientists report today (Sept. 3) in the journal PLOS ONE. Yet nothing is known about their lifestyle, their feeding habits, how they reproduce or if they float or attach to the seafloor.

"We don't even know if they're upside down," said lead study author Jean Just, a taxonomist at the Natural History Museum of Denmark.

Image: Photographs of 15 Dendrogramma specimens
Photographs of 15 Dendrogramma specimens. The ocean-dwelling creatures are so unusual that an entire new taxonomic family was created to classify them. Jean Just / PLOS One

The two new species described in the study were officially named Dendrogramma enigmatica and Dendrogramma discoides. Their tops are flat discs about 0.5 inches (about 1 centimeter) wide. Inside the discs, a fan of digestive tubes delivers nutrients, radiating outward like bicycle tire spokes. The center "mouth" opens into the stalk, and is probably for both eating food and excreting waste, Just said. (Many primitive species have this single gut.) Of the two new species, one has a shorter stalk and smaller disc compared with the other, though the difference is only a few millimeters. [ Image Gallery: Mysterious Ocean-Dwelling 'Mushrooms' ]

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Only 18 Dendrogramma specimens exist; they were all caught in 1988 on a research ship exploring the eastern Bass Strait between Australia and Tasmania. The weird creatures were found in a mix of seawater and sediment scooped from 3,280 feet (1,000 meters) below the ocean surface.

After returning to shore, scientists sifted through the marine life collected during the research cruise. Just, who was then at Australia's Museum Victoria in Melbourne, said he recognized the creatures were strange and special, but thought they were a new kind of jellyfish.

However, a closer look revealed no stinging cells, the hallmark of true jellyfish. No tentacles dangle from the Dendrogramma, and their tiny, hairless bodies also lack the swimming cilia that define comb jellies, another type of translucent ocean blob.

"They lack all of the characteristics that would put them in one phylum or another," Just told Live Science. "I think their closest relatives are probably the Cnidaria [true jellyfish] and the comb jellies, even if we can't place them in either of those phyla."

(A phylum is a taxonomic group one level below a kingdom. Humans and jellyfish are both in the kingdom Animalia, for instance.)

This is a condensed version of a report from LiveScience. Read the full report. Email Becky Oskin or follow her @beckyoskin. Follow us @livescience, Facebook & Google+. Original article on Live Science.

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