'Aliens of sea' provide new insight into evolution

May 21, 2014 by Lauran Neergaard
'Aliens of sea' provide new insight into evolution
This handout photo from the University of Florida is a composite showing different views of a comb jelly known as Pleurobrachia bachei as it swims. University of Florida researchers investigated the genes of this and other comb jelly species, and found the mysterious creatures evolved a unique nervous system in a different way than other animals. (AP Photo/University of Florida)

Exotic sea creatures called comb jellies may reshape how scientists view early evolution—as their genes suggest nature created more than one way to make a nervous system.

These beautiful but little-known translucent animals often are called "aliens of the sea," for good reason. Somehow, they rapidly regenerate lost body parts. Some even can regrow a very rudimentary brain.

Now in an in-depth look at the genes of 10 comb jelly species, researchers report that these mysterious creatures evolved a unique nervous system in a completely different way than the rest of the animal kingdom.

In other words, the nervous system evolved more than once, a finding published Wednesday by the journal Nature that challenges long-standing theories about animal development.

"This paper proves, on a genomic basis, they're truly aliens," said University of Florida neurobiologist Leonid Moroz, whose team spent seven years unraveling the genetics behind ' neural programming.

But the findings aren't just about evolutionary history. Comb jellies build a nervous system essentially using their own biological language, Moroz explained. That points to new ways to investigate brain diseases such as Alzheimer's or Parkinson's—maybe even, one day, the ability to engineer new neurons, Moroz said.

They "open to us completely unexpected windows," he said.

Moroz is exploring some of those windows using a unique floating laboratory that allows sophisticated at sea. In a test run off the coast of Florida this spring, The Associated Press documented how his team is studying which genes switch on and off as iridescent comb jellies regenerate from injury.

All animals evolved from a single ancestor. Scientists want to determine which branches broke off first, and how the earliest animals gradually changed to become more complex. The general theory: The oldest animals were the simplest, and once neural systems emerged, they evolved in a straightforward path from primitive nerve nets up to complex human brains.

This March 29, 2014 file photo shows University of Florida neurobiologist Leonid Moroz pulling a net from the Gulf Stream off the coast of Florida, to examine invertebrate species headed for his unique floating laboratory. New research with mysterious sea creatures called comb jellies suggests nature created more than one way to a nervous system. (AP Photo/Lauran Neergaard, File)

Moroz's team offered a dramatically different explanation.

The researchers mapped the full genetic code of the Pacific sea gooseberry, the nickname for a comb jelly species known as Pleurobrachia bachei. They also decoded gene activity of nine additional species of ctenophores—the scientific name for comb jellies. (The "c'' is silent.)

First, they found comb jellies represent the oldest branch of the animal family tree—not the simpler sea sponges traditionally thought to hold that spot, the team reported. That bolsters a similar finding published last December by competing scientists from the National Institutes of Health, which had been greeted with some skepticism.

And it's important in this context because sponges don't have neurons.

So what happened? Parallel evolution, Moroz proposed: While other branches of the animal family tree shared one path, the comb jellies essentially went down another street as they developed circuits of neurons, nerve cells that control such functions as motion and behavior. They simply don't have many of the genes that other animals use for neural development and function.

The results were "really weird," Moroz said. "Everybody from jellyfish to us have the same alphabet" when neurons communicate—but not the more ancient comb jellies.

For example, ctenophores don't use serotonin, dopamine and other common signaling chemicals, called neurotransmitters. Instead, they use methods unique to them.

"They're presenting data that's quite powerful," said biologist Antonis Rokas of Vanderbilt University, who wasn't part of the new work.

"It's almost like evolution has given us two different blueprints for building a structure that's very important," he added. "If your goal is to make a , it doesn't matter what the parts are in some ways. You could potentially mix and match. The more parts you have, the more solutions."

Explore further: Unique floating lab showcases 'aliens of the sea'

More information: The ctenophore genome and the evolutionary origins of neural systems, Nature, 2014. DOI: 10.1038/nature13400

Journal reference: Nature search and more info website

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sirchick
5 / 5 (7) May 21, 2014
Pleurobrachia bachei look far more alien and creatively different, than any hollywood movie ever thought of in any alien type film.

Good job nature!
Rupyro
4.7 / 5 (9) May 21, 2014
If a complex system like a nervous system was developed twice on just our earth. it proves that our complex biology is not nearly as rare as we feared. This gives me hope for extraterrestrial life, life always finds a way....
alfie_null
5 / 5 (7) May 22, 2014
I wonder why that type of nervous system was less successful. Some intrinsic quality that made it harder to scale up in complexity? Who's to say there aren't yet more ways to make nervous systems. Our biology is like this giant linear programming problem. Finding optimal solutions has been haphazard so far.
Vietvet
4 / 5 (8) May 22, 2014
I wonder why that type of nervous system was less successful. Some intrinsic quality that made it harder to scale up in complexity? Who's to say there aren't yet more ways to make nervous systems. Our biology is like this giant linear programming problem. Finding optimal solutions has been haphazard so far.


And far from perfect.
katesisco
1 / 5 (7) May 22, 2014
It isn't that their nervous system was less successful, it is the fact that our magnetar sun has always saturated Earth with energy every time it changed from a monopole (like now) to a dipole. Originally entirely monopolar, its death began when it developed dipolarity and the cycles decreased monopolarity in favor of dipolarity every magnetic reversal.
The life on Earth is the result, for better or worse.
Evolution is another name for the extended death of our monopole sun Sol.
supamark23
5 / 5 (6) May 22, 2014
It isn't that their nervous system was less successful, it is the fact that our magnetar sun has always saturated Earth with energy every time it changed from a monopole (like now) to a dipole. Originally entirely monopolar, its death began when it developed dipolarity and the cycles decreased monopolarity in favor of dipolarity every magnetic reversal.
The life on Earth is the result, for better or worse.
Evolution is another name for the extended death of our monopole sun Sol.


Uh, just how far up your butt did you have to reach to pull that bit of nonsense out?
Torbjorn_Larsson_OM
5 / 5 (4) May 22, 2014
That is consistent with the December find that ctenophores has evolved muscle tissue (which I assume generally need neural control and activation) independently too.

"Pleurobrachia bachei look far more alien and creatively different, than any hollywood movie ever thought of in any alien type film."

WTF, Evolution? http://wtfevoluti...blr.com/

@Rupyro: Agreed!
Torbjorn_Larsson_OM
5 / 5 (3) May 22, 2014
@alfie_null: This hints that there are several basic ways. Then you get to another problem, which seems to have been solved twice, the cortex in vertebrates/mushroom bodies in invertebrates. We had no success making neural nets (nn) that didn't overtrain. (I.e. started to use inessential, later confusing details in the training set for qualitative assessment, such as "humans must have eyes above mouth" if training photos were only everyday oriented.)

Then 2006 someone managed to emulate what the cortex did with regular circuits. Turned out that it was the first nn that could be trained forever. It spontaneously organized symbol-like identifiers. (I.e. put details of humans together in physically close nn memory.) It isn't just language that are symbol oriented it seems, or rather our language evolution is likely premeditated by mapping to brain organization. Solve the problem once, repeat as necessary...
Frank_Lowe
not rated yet May 24, 2014
If our blood is Red with all thats in it.
Isn't the Sea the blood of the Earth with all thats in it ??
sirchick
not rated yet Jun 10, 2014
If our blood is Red with all thats in it.
Isn't the Sea the blood of the Earth with all thats in it ??


Wouldn't the blood of earth be the contents in the earth under the surface not the water on the surface..the water on the surface is still a tiny amount of mass of the entire mass of the planet.

Given our blood isn't pooled on the surface of the skin - not sure the ocean is the best comparison :P
Frank_Lowe
1 / 5 (1) Jun 11, 2014
I think you all are substance abusers.Where do you get the crap you wright .
.
rockwolf1000
5 / 5 (1) Jun 11, 2014
I think you all are substance abusers.Where do you get the crap you wright .
.


Do you wreally? Is that wright? Should we give it a wrest? Keep it wreal yo!

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