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Single-Celled Giant Upends Early Evolution
by Discovery
Reposted from:
http://dsc.discovery.com/news/2008/11/20/gromia-cambrian.html
Nov. 20, 2008 -- Slowly rolling across the ocean floor, a humble single-celled creature is poised to revolutionize our understanding of how complex life evolved on Earth.
A distant relative of microscopic amoebas, the grape-sized Gromia sphaerica was discovered once before, lying motionless at the bottom of the Arabian Sea. But when Mikhail Matz of the University of Texas at Austin and a group of researchers stumbled across a group of G. sphaerica off the coast of the Bahamas, the creatures were leaving trails behind them up to 50 centimeters (20 inches) long in the mud.
The trouble is, single-celled critters aren't supposed to be able to leave trails. The oldest fossils of animal trails, called 'trace fossils', date to around 580 million years ago, and paleontologists always figured they must have been made by multicellular animals with complex, symmetrical bodies.
But G. sphaerica's traces are the spitting image of the old, Precambrian fossils; two small ridges line the outside of the trail, and one thin bump runs down the middle.
At up to three centimeters (1.2 inches) in diameter, they're also enormous compared to most of their microscopic cousins.
"If these guys were alive 600 million years ago, and their traces got fossilized, a paleontologist who had never seen this thing would not have a shade of doubt attributing this kind of trace to the activity of a big, multicellular, bilaterally symmetrical animal," Matz said.
"This is a very important discovery," Shuhai Xiao of Virginia Polytechnic Institute said. "The fact that protists can make traces has important implications for how we interpret many trace fossils."
The finding could overturn conventional thinking on a mysterious time in the evolution of early life known as the Cambrian Explosion. Until about 550 million years ago, there were very few animals leaving trails behind. Then, within ten million years an unprecedented blossoming of life swarmed across the planet, filling every niche with hard-bodied, complex creatures.
"It wasn't a gradual development of complexity," Matz said. "Instead these things suddenly seemed to burst out of a magic box."
Charles Darwin first noticed the Cambrian Explosion and thought it was an artifact of a poorly preserved fossil record. The precambrian trace fossils were left by multicellular animals, he reasoned, so there must be some gap in fossils between the nearly empty Precambrian and the teeming world that quickly followed. But if the first traces were instead made by G. sphaerica, it would mean the Explosion was real; it must have been a diversification of life on a scale never before seen.
Genetic analysis of the water-filled G. sphaerica cells also reveals tantalizing clues that it could be the oldest living fossil on the planet.
"There's a 1.8 billion-year-old fossil in the Stirling formation in Australia that looks just like one of their traces, and with a discoidal body impression similar to these guys." Matz said. "We haven't proved anything, but we might be looking at the ultimate living macroscopic fossil."
Comments 1 - 50 of 56 |
Reload Comments | Back to Top | Page Numbers3. Comment #287862 by SmartLX on November 20, 2008 at 7:17 pm
Awwwww crap. You just know creationists are gonna work that "magic box" quote for years to come.Edit: Ooooooohhhhhh, right, it's Discovery. Never mind.
Edit-edit: Hang on, it's the Channel rather than the Institute. Awwwww crap.
Other Comments by SmartLX
4. Comment #287865 by Sittingduck on November 20, 2008 at 7:27 pm
You just know creationists are gonna work that "magic box" quote for years to come.
yea, probably, but the operative word is "fossil".
Like Lewis Black says "I like to keep a fossil in my pocket and when a creationist says the earth is 6,000 years old, I pull it out and say "FOSSIL!" Then I throw it over their heads".
Other Comments by Sittingduck
5. Comment #287869 by Evilcor on November 20, 2008 at 7:49 pm
What's the big deal? I've been keeping these things as pets for ages! :) Other Comments by Evilcor
6. Comment #287874 by Don_Quix on November 20, 2008 at 8:22 pm
Giant single cells?? Well duh. Goddidit! Clearly this disproves evolution and proves the earth is only 6,000 years old and proves there is a god and proves that the god of the old testament is the only real god and proves that anyone who doesn't strictly follow only the strictest of old testament interpretations of christianity/judaisim is going to burn for all eternity in HELL!!!!!!I'm just kidding. This is pretty cool :)
Other Comments by Don_Quix
7. Comment #287876 by j.mills on November 20, 2008 at 8:40 pm
There's a 1.8 billion-year-old fossil in the Stirling formation in Australia that looks just like one of their traces...so no doubt we will see a photo of that fossil trace in the next edition of Atlas of Creation. Next to a photo of a grape...
Other Comments by j.mills
8. Comment #287878 by hoops mccann on November 20, 2008 at 8:47 pm
I can't wait until they map the genome of this beast. Other Comments by hoops mccann
9. Comment #287880 by Auld on November 20, 2008 at 9:02 pm
How do you define Protist? If it is defined as an eukaryotic microorgansim, then this beast is not a Protist since it's macroscopic.Other Comments by Auld
10. Comment #287886 by Psi Wavefunction on November 20, 2008 at 9:17 pm
Auld,Protist = All eukaryotes besides plants, animals and fungi. Ie. the other 99% of euk diveristy =D
Size has nothing to do with it. Giant kelps, the ones that make up the beautiful kelp forests of the Pacific coast, are protists too - they have a VERY distant relationship with either plants or animals...
There's also some foraminiferans (also protists) that can get quite big - around 20cm at times. Don't know whether they leave a trail, but they leave behind beautiful fossils -- a foram is a snail-like thing, only unicellular but with many nuclei. Large multinucleate cells are actually not that unusual -- they appear as some seaweeds, as slime moulds, some fairly large amoebozoans (genus Chaos can be seen with a dissecting scope, which is quite nice for a unicellular thing).
Some fungi are microscopic, but are NOT protists... so again, the size thing has no bearing on actual biological classification.
It is quite understandably confusing though -- Protista is not a "natural" (monophyletic) group.
And hoops mccan, it's unlikely that its genome will be sequenced soon, unfortunately. It's a large amoebozoan, thus it's quite likely it may have a fairly large genome. I'll need to check if it's closely related to the likes of genus Amoeba (http://en.wikipedia.org/wiki/Amoeba_dubia), where some members have a genome 200x that of ours. It's simply too big to sequence cheaply enough at this time. Although probably in 5-10 years we'll get even faster!
This is quite amazing though -- once again our zoocentric ego is crushed by a few stronger voices for the rest of diversity! =D
(now before a microbiologist gets here and crushes my eukaryocentric ego <_< .... )
-Psi-
Other Comments by Psi Wavefunction
11. Comment #287887 by Butler on November 20, 2008 at 9:22 pm
It's amazing that single-celled organisms can get this large. I wonder what peculiarities of their genome and/or environmental factors led them down the path to gigantism, rather than multicellularity? Other Comments by Butler
12. Comment #287893 by Psi Wavefunction on November 20, 2008 at 10:16 pm
Oh, and a source for the 20cm foraminiferan:Xenophyophore:
http://oceanexplorer.noaa.gov/explorations/05lostcity/logs/july27/media/xeno2.html
(began doubting myself...)
That thing is all one single cell. Amazing!
Edit:
Further Edit: Apologies... Gromia was found to be a cercozoan (Burki et al. 2002, Protist) , which IS in the same superkingdom as forams but still fairly distantly related...
Other Comments by Psi Wavefunction
13. Comment #287898 by Eshto on November 20, 2008 at 11:09 pm
Someone help me out here, is that a picture of a giant single celled thing? If so, why does it look like it's made up of a bunch of smaller things? Other Comments by Eshto
14. Comment #287900 by DamnDirtyApe on November 20, 2008 at 11:31 pm
A lot can happen in 550 million years.Other Comments by DamnDirtyApe
15. Comment #287904 by Psi Wavefunction on November 21, 2008 at 12:15 am
Eshto, It seems this creature has a test (shell), so what you're seeing is the pattern of its shell. The pseudopods (feet) actually protrude from a hole at the bottom. Having trouble finding a pic of Gromia sphaerica, but here's a random testate amoeba (although of a very different group) http://www.pirx.com/droplet/gallery/arcella/arcella3.jpg
And a random Gromia species: http://protist.i.hosei.ac.jp/pdb/images/Sarcodina/Gromia/sp_3.html
Hope that helps...?
Cheers,
-Psi-
Other Comments by Psi Wavefunction
16. Comment #287913 by Quetzalcoatl on November 21, 2008 at 12:49 am
Cool! Other Comments by Quetzalcoatl
17. Comment #287916 by gazzaofbath on November 21, 2008 at 12:54 am
Apart from the fascination of this large single celled animal the article is implying that the "Cambrian Explosion" of life was even more dramtatic than had been suspected. There doesn't appear to be any compelling case of multi-celled animals before about 550 million years at all - everything appeared so quickly then! Amazing.
Most often evolutionary changes are gradual but there do appear to be occasions when something dramatic can be triggered too.
Other Comments by gazzaofbath
18. Comment #287917 by Quetzalcoatl on November 21, 2008 at 1:08 am
gazzaofbath-
Reasonably complex animals probably did exist before 550 million years ago (early molluscs and echinoderms), and it's possible that the Explosion wasn't as remarkable as has been thought:
http://en.wikipedia.org/wiki/Cambrian_explosion#How_real_was_the_explosion.3F
Other Comments by Quetzalcoatl
19. Comment #287918 by BicycleRepairMan on November 21, 2008 at 1:12 am
Then, within ten million years an unprecedented blossoming of life swarmed across the planet, filling every niche with hard-bodied, complex creatures.
"It wasn't a gradual development of complexity," Matz said. "Instead these things suddenly seemed to burst out of a magic box."
This is a ridiculuos thing to say, as most people will interpret this completely wrong. OF COURSE it was a gradual development, but compared to everything else in nature, the development was lightning fast. Still, it DID take 10 million years, which is one thousand times longer than civilizations history, a timescale that most of us have trouble imagining, but which is a mere blink of an eye compared to the total age of the earth.
Other Comments by BicycleRepairMan
20. Comment #287919 by bendigeidfran on November 21, 2008 at 1:13 am
Sounds huge to me. What is the next biggest known single cell' Other Comments by bendigeidfran
21. Comment #287922 by Not the Messiah on November 21, 2008 at 1:23 am
Anyone else wondering what they taste like?..Other Comments by Not the Messiah
22. Comment #287923 by Quetzalcoatl on November 21, 2008 at 1:25 am
Not the Messiah-
Like slime, probably. Try some of the algae on a pond, the taste will probably be comparable.
Bicycle Repair Man-
I agree, that's a stupid thing to say, the fundies will be jumping all over it. It's just as likely that prior to the ten million year period there were complex creatures, but their bodies weren't quite hard enough to fossilise well. Improvements in predation techniques could easily have led to a corresponding defensive response within that timescale.
Other Comments by Quetzalcoatl
23. Comment #287932 by irate_atheist on November 21, 2008 at 2:10 am
20. Comment #287919 by bendigeidfran -What is the next biggest known single cell?Wooter's brain.
Other Comments by irate_atheist
24. Comment #287936 by Stafford Gordon on November 21, 2008 at 2:25 am
Wow!Our twin daughters are being offered places on biology courses at a number of universities; they're both passionate about the subject and are also studying maths, further maths and chemistry.
There couldn't be a better time for it.
I must hasten to add, that their intellegence comes from their mother's side and not mine alas; but I'm learning a lot.
Other Comments by Stafford Gordon
25. Comment #287937 by Anvil on November 21, 2008 at 2:38 am
NTM:Anyone else wondering what they taste like?..
Chicken, apparently...
Read a real interesting book on the development of the 'eye' as a prime mover in the Cambrian Explosion; proto-trilobites open their proto-eyes and go 'Look lads... Lunch' starting an arms race that lasted till round about now. Will shoot off and try and find it... (did that) 'In the blink of an eye: How vision kick-started the big bang of evolution' - Andrew Parker. ISBN 0-7432-5733-2
sorry, forgot the eye is irreducibly complex.
AS
Other Comments by Anvil
26. Comment #287939 by DoctorE on November 21, 2008 at 2:47 am
WOW, this is facinating!!! Other Comments by DoctorE
27. Comment #287964 by DamnDirtyApe on November 21, 2008 at 3:52 am
Giant single celled organism... AARRGHH!!! THE BLOB!Other Comments by DamnDirtyApe
28. Comment #287968 by CaptainMandate on November 21, 2008 at 4:03 am
this is awesome
however:
"Single-Celled Giant Upends Early Evolution"
translates to me as "Scientists admit Evolution is a big lie: REPENT! they're going to hell, it's not too late for you"
or something
Other Comments by CaptainMandate
29. Comment #288069 by SilentMike on November 21, 2008 at 6:06 am
"It wasn't a gradual development of complexity," Matz said. "Instead these things suddenly seemed to burst out of a magic box."
It's a 10 million year long "explosion" for crying out loud. It may be a bit fast in geological terms, but it's certainly gradual.
Other Comments by SilentMike
30. Comment #288106 by Ishruul on November 21, 2008 at 6:54 am
Finally a picture of the cute little critter. Screw snail race, Gromia sphaerica kick ass ;) Other Comments by Ishruul
31. Comment #288135 by jeremynel on November 21, 2008 at 7:55 am
"It wasn't a gradual development of complexity," Matz said. "Instead these things suddenly seemed to burst out of a magic box."
Oh Christ, not again...
Other Comments by jeremynel
32. Comment #288136 by Titania on November 21, 2008 at 7:57 am
I hope Richard speaks out on the magic box statement and the Cambrian explosion postulations as well. Richard? Other Comments by Titania
33. Comment #288145 by Friend Giskard on November 21, 2008 at 8:13 am
It wasn't a gradual development of complexity...
Aw crap. That's a bad slip.
Other Comments by Friend Giskard
34. Comment #288147 by Puf_Almighty on November 21, 2008 at 8:15 am
Auld, a better definition of Protist would be "single-celled eukaryote." Previously those things were invariably microscopic, so calling Protists "eukaryotic microorganisms" was perfectly fair.For instance, Order Struthioniformes contains ostritches and cassowaries and such, and if asked for a definition you'd most likely give "An order of large, flightless birds with no keel-bone." But if we then found some extant Struthioniform with a keel-bone, and thusly functional wings and possibly flight, we'd have to re-write that whole definition.
That's how awesome and weird this discovery is- it means re-writing the definition of "Protist". That's a big deal.
Other Comments by Puf_Almighty
35. Comment #288154 by Steve Zara on November 21, 2008 at 8:31 am
But if the first traces were instead made by G. sphaerica, it would mean the Explosion was real; it must have been a diversification of life on a scale never before seen.
No. It just means that we have no evidence either way for the timescale of the diversification.
Other Comments by Steve Zara
36. Comment #288183 by Euderma on November 21, 2008 at 9:57 am
re: 10. Comment #287886 by Psi WavefunctionKelp are protists but aren't they multicellular? I have always heard that Caulerpa are the largest single-celled organisms.
re: 20. Comment #287919 by bendigeidfran
The largest single cell is usually considered to be the ostrich egg.
Other Comments by Euderma
37. Comment #288185 by NewEnglandBob on November 21, 2008 at 10:02 am
I agree with you, Steve. Their conclusion should not come from that presumption. The article speculates. Other Comments by NewEnglandBob
38. Comment #288199 by InfuriatedSciTeacher on November 21, 2008 at 10:23 am
36 and the others on the taxonomy:Protists were re-defined a few years ago to include multi-cellular eukaryotes that lack cellular specialisation (read: Algae)... so presumably any Eukaryote without specialised cells, which includes those that only have one cell, would be classified as a Protist.
Any adjustment to the time scale would have to be conjecture, as we still can't presume what made all of the fossil trails being examined. That, and since we've seen examples of natural selection that take a matter of decades (lizard articles), 10 million years is still quite gradual.
Other Comments by InfuriatedSciTeacher
39. Comment #288222 by mitch_486 on November 21, 2008 at 11:01 am
This article has inspired me to look into the world of fossil collecting. It's actually quite easy to order them online (with attention to site quality)
I'd like to share with you just one site I have found. It will send shivers down your spine to think of owning such beautiful things.
http://www.stonesbones.com/dino1.htm
Edit: Interestingly, a quick google search of Keichousaurus hui (little dino in the link I provided) brought up it's mention over on Pharyngula
http://pharyngula.org/index/weblog/comments/keichousaurus_hui/
cheers!
Other Comments by mitch_486
40. Comment #288237 by Border Collie on November 21, 2008 at 11:54 am
So, OK, did Noah try to find a boy and a girl, and if so, how could he tell, or did he disobey God and just take one, hoping it would do the mitosis thing? Would God have been pissed if Noah had taken two and they became four? Questions, questions, questions ...
Anvil ... I've read Parker's book ... I'm not scientist enough to know how valid it is, but I found it very interesting.
Other Comments by Border Collie
41. Comment #288241 by Border Collie on November 21, 2008 at 12:16 pm
Irate ... Thanks alot! I just sprayed a mouthful of water all over my computer terminal and keyboard when I read your comment about Wooter. Still LMAO ... where's the hairdryer? Other Comments by Border Collie
42. Comment #288248 by D'Arcy on November 21, 2008 at 12:33 pm
Is Wooter's brain as big as an ostrich egg?
Hell, now that is speedy evolution!
Other Comments by D'Arcy
43. Comment #288321 by CambrianExplosion on November 21, 2008 at 2:24 pm
I approve this discovery! :) Other Comments by CambrianExplosion
44. Comment #288324 by AoClay on November 21, 2008 at 2:32 pm
I'll go read Wonderful Life again.and Zara thanks, because that ran through my head too, glad to see somebody smarter than me went "wait...what?"
Other Comments by AoClay
45. Comment #288335 by Opisthokont on November 21, 2008 at 3:01 pm
Auld, Psi Wavefunction, Puf_Almighty, Euderma, InfuriatedSciTeacher, and anyone else interested in the definition of "protist": Every protistologist that I have met (and I'm in the field myself, so I have met a good few) has a slightly different definition of the term "protist". Some advocate the alternate term "protoctist" as an explicit indicator of any eukaryote that is not an animal, plant, or fungus, which is one of the more common definitions of "protist". This has not caught on in the protistology community at large, but at least it is unambiguous. As it happens, while each protistologist has hir own definition of the term, I am not aware of much argument about it, since most (like myself) tend to avoid the term altogether. We go to meetings sponsored by groups with names like "the International Society of Evolutionary Protistology" and talk about eukaryotes.Hope that helps.
Other Comments by Opisthokont
46. Comment #288386 by InfuriatedSciTeacher on November 21, 2008 at 7:27 pm
Opisthokont> fair enough... I was offering my best working definition since algae have been moved from Plantae to Protista... and as I'm an ecologist by training, specifically marine, I wouldn't presume it to be perfect. I learned taxo because I had to, not because it's particularly useful in studying interactions.Other Comments by InfuriatedSciTeacher
47. Comment #288393 by b0ltzm0n on November 21, 2008 at 7:59 pm
Like Lewis Black says "I like to keep a fossil in my pocket and when a creationist says the earth is 6,000 years old, I pull it out and say "FOSSIL!" Then I throw it over their heads".
Oh! I love that! My favorite line from that standup routine was something like, "evolution is a major thread in the larger tapestry that I like to call... REALITY!!!!" Classic!
Other Comments by b0ltzm0n
48. Comment #288676 by Titania on November 22, 2008 at 6:27 am
39. Comment #288222 by mitch_486
Thanks for that link!
I bought some trilobite fossils for my nephew last week in Arizona, but I may have to pick up one of these.
Mitch, are you a student?
Other Comments by Titania
49. Comment #288893 by Psi Wavefunction on November 22, 2008 at 4:47 pm
Main point: Multicellularity and size has nothing to do with the protist definition. According to a handful of world experts in protist phylogeny, who I am currently taking a course from:Protist = Eukaryote that is not a plant, animal or fungus.
And... WTF... I just typed up a large explanatory post and hit submit and it disappeared...!
Nothing angers me more than my work magically disappearing! That's why I hate electronic stuff sometimes.
Anyway I'll just post a couple pictures since I'm too damn lazy to retype the whole thing:
Keeling et al. 2005 Trends Ecol Evol:
http://scienceblogs.com/evolgen/upload/2006/08/Eukaryote_tree.jpg
Gromia is in 'rhizarians'. Find animals and land plants. Good luck!
Protist is all of that tree except for land plants, animals and the fungal clade (chytrids to asco- and basidiomycetes).
Brown algae (kelps etc) are phaeophyta, in chromalveolate group.
Plasmodium (malarial parasite, Apicomplexa) is also in chromalveolate group, as is paramecium (ciliate), diatoms and things that cause massive algal blooms (haptophytes)
Euglena is in excavates. As are the things that cause African Sleeping Sickness, Chagas Disease, etc (Kinetoplastids).
Red algae are in the green algal kingdom.
It's confusing for historical reasons. Life was once classified in motile (animals) and sessile (plants)...
To complicate things further, sometimes things ate each other and the victims actually became organelles, like mitochondria and plastids. This occurred more than once:
Keeling 2004 Am J Bot:
http://images.the-scientist.com/content/figures/0890-3670-050606-22-1-2.jpg
Hope that clears things up a bit!
-Psi-
PS: Multicellularity has arised multiple times in evolution, so is not a defining character of animals/plants/fungi by any means. Kelps are multicellular. Slime moulds are arguably half way there. Red algae are also independently multicellular.
Also, there has been cases of multicellular organisms reducing to a unicellular one. Eg. myxosporidia http://www.scielo.br/img/revistas/mioc/v100n3/a05fig01.jpg
http://www.thefreedictionary.com/Myxosporidia (suprisingly up-to-date! wow...)
Other Comments by Psi Wavefunction
50. Comment #289057 by Titania on November 23, 2008 at 6:45 am
Ancient microbes made giant magnets - Magnetic fossils show how climate change creates new extremes.
http://www.freerepublic.com/focus/f-news/2110792/posts
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1. Comment #287858 by Sittingduck on November 20, 2008 at 7:10 pm
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