A New Phylum?

[Ultimate Paragon]

http://www.nature.com/news/sea-creatures-add-branch-to-tree-of-life-1.15833

Scientists have identified two mushroom-shaped marine animals that do not fit in any of the known categories of the tree of life and could be related to groups thought to be extinct for 500 million years.

Jean Just, a zoologist at the Natural History Museum of Denmark in Copenhagen, discovered 18 odd-looking invertebrate specimens while sorting through materials he had collected in the Tasman Sea in 1986. On that expedition, he was exploring the continental slope off the southeastern coast of Australia using a sled that drags over the bottom of the ocean floor and collects animals that live there.

In the study, which appears in PLOS ONE1, the researchers report 14 specimens, collected at depths of 400 and 1,000 metres, that could not be classified into any major groups, or phyla. These “little, funny, mushroom-shaped animals,” as Just calls them, are multicellular, mostly asymmetrical — a crucial characteristic for classifying organisms — and have a gelatinous layer between the inner and the outer body.

The researchers classified the organisms under a new genus, Dendrogramma — a reference to dendrograms, the tree diagrams used in biology to illustrate evolutionary relationships between organisms. The two species names, enigmatica and discoides, allude to their mysterious character and disc shape, respectively.

The samples were initially fixed in formaldehyde and brought back to the laboratory, where they were stored for a time in alcohol, precluding the possibility of later DNA extraction and analysis to determine their relationships to other organisms.

Under a microscope the samples showed morphological similarities to two existing groups, jellyfish and comb jellies. This suggests that they may be related to one of these groups, although at the moment they cannot be classified as either.

“It would be incredibly exciting if the authors have found a previously unknown group of animals that diverged from other animals so early,” says Casey Dunn, an evolutionary biologist at Brown University in Providence, Rhode Island.

The researchers also found similarities — such as the same branching pattern and lobe-like structures around the mouth opening — between Dendrogramma and a small group of 'medusoids', or jellyfish-like creatures, that lived 600 million years ago during the Ediacaran period.

Tetyana Nosenko, an evolutionary biologist at Ludwig Maximilian University in Munich, Germany, says that “this discovery implies an exciting possibility that the deep-sea of Australia has preserved living descendants of the Ediacara organisms, which were thought to be extinct over 500 million years ago.”

New species are discovered all the time — the 1984 Australian expedition alone yielded somewhere between 200 and 300. But finding one that does not fit within the known tree of life has happened only two or three times in the past 15–20 years, says Just.

The implications of this are staggering.

[Second Coming of Madman]

Wow.

[Cerim Treascair]

Well, this is nifty!

[Askold]

“this discovery implies an exciting possibility that the deep-sea of Australia has preserved living descendants of the Ediacara organisms, which were thought to be extinct over 500 million years ago.”

I have a bad feeling about this... How could a species survive 500 million years of Australia, the place where everything is trying to kill you and venomous ducks-beaver-hybrids roam freely?

The only logical answer is that those creatures are even deadlier than anything else living near Australia!

[Zygarde]

The only logical answer is that those creatures are even deadlier than anything else living near Australia!

Such a possibility bolth scares me and intrigues me, Although it could be that nothing near Australia can eat it since it may be poisonous or something of that nature.

[Random Gal]

Sweet! I was actually trying to classify some of those odd Ediacaran fossils as part of an Invertebrate Paleontology project a few years ago, so it's interesting that we've apparently got some living relatives of them.

As for "new phylum" etc., the Linnean ranking system's been broken for decades and everyone knows it.

[Second Coming of Madman]

The only logical answer is that those creatures are even deadlier than anything else living near Australia!

Such a possibility bolth scares me and intrigues me, Although it could be that nothing near Australia can eat it since it may be poisonous or something of that nature.

So that's where the rest of the family went. Jeez, I knew that they were running low on competition in the environs. But Australia? Wow, they were desperate for a good fight.

[Nemo]

Cue the creationists saying "LIVING FOSSIL!!!!"

The Linnean ranking system is useful for taking a snapshot of life during one moment of time. It's pretty well done for it's time, but I also agree the phylogeny knocks it out of the park.