Thursday, March 3, 2011

Walking cactus discovered in China

By Wynne Parry

The so-called walking cactus belongs to a group of extinct worm-like creatures called lobopodians that are thought to have given rise to arthropods. Spiders and other arthropods have segmented bodies and jointed limbs covered in a hardened shell.

Before the discovery of the walking cactus, Diania cactiformis, all lobopodian remains had soft bodies and soft limbs, said Jianni Liu, the lead researcher who is affiliated with Northwest University in China and Freie University in Germany.

"Walking cactus is very important because it is sort of a missing link from lobopodians to arthropods," Liu told LiveScience. "Scientists have always suspected that arthropods evolved from somewhere amongst lobopodians, but until now we didn't have a single fossil you could point at and say that is the first one with jointed legs. And this is what walking cactus shows." [Image of walking cactus fossil]

Liu and other researchers described the extinct creature based on three complete fossils and 30 partial ones discovered in Yunnan Province in southern China. The walking cactus had a body divided into nine segments with 10 pairs of hardened, jointed legs, and it measured about 2.4 inches (6 centimeters) long.

It's not clear how the leggy worm made its living. It could have used its tube-like mouth called a proboscis to suck tiny things from the mud, or it may have used its spiny front legs to grab prey, Liu said.

Clues to arthropod evolution are preserved in modern-day velvet worms, which are considered the only living relative to all arthropods. Once mistaken for slugs, these land-dwelling worms are almost entirely soft-bodied except for hardened claws and jaws.

The discovery of the walking cactus helps fill in the evolutionary history between the velvet worms and modern arthropods, which, in terms of numbers and diversity, are the most dominant group of animals on the planet, according to Graham Budd, a professor of paleobiology at Uppsala University in Sweden, who was not involved in the current study.

The walking cactus is the first and only case of hardened, jointed limbs built for walking appearing in a creature that is not recognizable as an arthropod, Budd said.

But Budd is not convinced that, as the researchers argue, the walking cactus's hardened legs were passed directly down to modern arthropods.

"I am not persuaded that it is a direct ancestor or as closely related to living arthropods as they suggest," he told LiveScience. "I would like to see more evidence; the great thing is a lot more material keeps coming up."

For instance, it is possible that the walking cactus is less closely related to modern arthropods, and that hardened legs evolved multiple times. It is also possible that the bodies of primitive arthropods hardened before their legs did, Budd said.

New fossils, particularly from China, have helped clarify the evolutionary history of arthropods, and in the last decade or so, scientists have come to more consensus regarding that history, he added.

(http://www.csmonitor.com/Science/2011/0225/Walking-cactus-discovered-in-China)

23 comments:

  1. So it's not an actual cactus then :(
    Good discovery though :)

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  2. @paranormal I was just going to write the same thing. Not *really* a cactus though. But interesting non the less. I mean, the science behind that.

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  3. Anyone who has ever played Super Mario 2 can attest to the existence of these beasties!

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  4. I was thinking it was some sort of actual creature like those trees in LOTR. How do you find all of your information?

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  5. That's a pretty cool find! Thanks for the post! LOL @ the SMB 2 comparison, Aaron!

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  6. hi, walking cactus reporting in

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  7. Did the pic of him walk off the page?

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  8. These guys are from the Ediacaran period. Truly a unique phase in the development of life. I wish they had mentioned this. It was a period where live seemed to be trying out all sorts of different body styles. It is also important to astrobiology because it gives insight on to what other critters in our Universe might look like.

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  9. Wow that's so weird... followed!

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  10. Did insects really have to evolve to be soooo freaking creepy?

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  11. I waiting for walking Marijuanas!

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  12. That is weird and interesting but not actual cactus, thank goodness.

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  13. Jesus that's creepy. Anything spider/scorpion-like I wanna stay away from. Interesting find though!

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  14. @donga I think that's their evolutionary purpose.

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  15. I wanted to be a real cactus so bad!

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  16. Title was a bit misleading haha but I still find it awesome, thanks!

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  17. 'leggy worm' is a curious term for scienticians to be using.

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  18. hahah same with everyone else, i thought this was going to be about a cactus that could walk xD

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  19. man there's no telling what kind of crazy creatures once lived

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