Penis Worms Help Solve Evolutionary Puzzle

[azbob]

Enigmatic marine invertebrates known as penis worms are shedding new light on the evolution of digestion, while posing a curious embrionic question: which develops first, the mouth or the anus?

To produce the first description of the entire fetal development of penis worms, or priapulids, Swedish and Norwegian researchers looked at which genes are expressed during the development of the gut, the mouth and the anus in three-day-old worm embryos. In particular, they investigated embryos belonging to Priapus caudatus worms.

Living in shallow waters and measuring up eight inches long, these worms are "living fossils" that have changed very little since their priapulid ancestors thrived on the ocean floor in the Cambrian period some 500 million years ago.

Detailing their findings in the journal Current Biology, the researchers noticed that priapulids form their guts like humans, fish, frogs, starfish and sea urchins. Furthermore, exactly the same genes are involved in the process.

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"It does not mean that these penis worms are now closely related to humans," lead researcher Andreas Hejnol, at the Sars International Centre for Marine Molecular Biology in Norway, said.

"The fact that different animals share a common way of forming the gut suggests that the embryological origins of the human intestine and how it develops are much older than previously thought -- most likely over 500 million years," Hejnol said.

Priapulids are thought to be among the first bilaterally symmetric animals (those with a left and right body side) which today make up 99 percent of all living animals.

Historically, bilaterally symmetric animals have been divided into two groups based on the difference in how the gut develops in the fetus. At an early stage of fetal development, some cells move into a region called the blastopore.

"The important point is that in some animals this region becomes the mouth, while in others it becomes the anus," Hejnol said.

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The two groups -- protostomes (from the Greek for "mouth first") and deuterostomes ("mouth second") -- have defined separate branches of the evolutionary tree since 1908.

Priapulids and most other invertebrates fell into the protostome group, in which the mouth formed first, and the anus second.

Vertebrates and a few spineless animals were placed into the deuterostome category. (Yes, our anuses develop before our mouths).

Now several evolutionary biologists believe that the classification will have to be reconsidered.

"Here is an animal that is the poster child for early protostomes, and it develops just like a deuterostome," Mark Martindale, a developmental biologist at the University of Hawaii in Honolulu, told Nature.

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"We’ve been using the name protostome for 100 years, and now it’s clear that it doesn’t mean anything," he said.

Apart from shaking the branches of the animal tree, the research shows how important it is to study the vast diversity of animals found in the oceans.

"Priapulids still hide a lot of secrets to unravel, which will have a great influence on our understanding of the origin of other major organs, such as the brain, blood or legs," Hejnol said.

Penis worms reproduce in winter time, so Hejnol and colleagues have to travel regularly to the west coast of Sweden during the ice-cold season to get them.

"We sail the fjords dredging in areas where they are abundant, collecting animals and later getting embryos from them in the lab," first author José M. Martín-Durán said.

"Although thrilling, sometimes the collection trips turn into real adventures, with low temperatures, snow or even frozen waters," he added.

http://news.discovery.com/animals/penis-worms-digestion-evolution-121030.html

 

[TJ99]

Interesting article, but I can't help but giggle at those pics. Dongworms.

 

[be.plato]

I didn't know there even was an Evolutionary Puzzle? I thought it was proven beyond all reasonable doubt.

 

[pampoenskyf]

I didn't know there even was an Evolutionary Puzzle? I thought it was proven beyond all reasonable doubt.

if you move half the distance from a wall closer to the wall every odd minute, will you ever touch the wall?
Sounds reasonable doesn't it?

 

[azbob]

Interesting article, but I can't help but giggle at those pics. Dongworms.

 

[TJ99]

I didn't know there even was an Evolutionary Puzzle? I thought it was proven beyond all reasonable doubt.

ERMAHGERD!!! I thought stars were proven beyond all reasonable doubt, yet they discover new stars all the time, AND learn new things about existing stars? WHAT SORCERY IS THIS?????

Nice try but too obvious, troll better next time.

 

[be.plato]

if you move half the distance from a wall closer to the wall every odd minute, will you ever touch the wall?
Sounds reasonable doesn't it?

But do we know how far away the wall is? So how do we know how close we are....

 

[be.plato]

ERMAHGERD!!! I thought stars were proven beyond all reasonable doubt, yet they discover new stars all the time, AND learn new things about existing stars? WHAT SORCERY IS THIS?????

Nice try but too obvious, troll better next time.

Its not about trolling

Worms with human brains? LOL, awesome joke for the morning, thanks

 

[mercurial]

We're all worms

 

[TJ99]

Its not about trolling

Worms with human brains? LOL, awesome joke for the morning, thanks

Not trolling, yet you completely misquote what the article says and pretend it's a joke. Gotcha.

 

[be.plato]

Not trolling, yet you completely misquote what the article says and pretend it's a joke. Gotcha.

Ok, to correct myself:

NEWS: Human-Like Brain Found in Worm

Human like?

 

[TJ99]

Reading the actual article would help, not just the title which is chosen for exactly the purpose of making people go :wtf: and read it.

They discovered brain structures similar to those of all vertebrates, not just humans, in an invertebrate worm, which they previously though didn't have such structures. Sort of precursor cells which developed into the far more complex brains in later animals. Like humans. It's not like they're suggesting it's actually a freaking fully-formed human brain in a tiny little sea creature.

 

[be.plato]

Reading the actual article would help, not just the title which is chosen for exactly the purpose of making people go :wtf: and read it.

They discovered brain structures similar to those of all vertebrates, not just humans, in an invertebrate worm, which they previously though didn't have such structures. Sort of precursor cells which developed into the far more complex brains in later animals. Like humans. It's not like they're suggesting it's actually a freaking fully-formed human brain in a tiny little sea creature.

ok phew, for a minute there I thought they had found the missing link.

 

[azbob]

It's not like they're suggesting it's actually a freaking fully-formed human brain in a tiny little sea creature.

My human-like brain almost exploded trying to imagine that

 

[porchrat]

ok phew, for a minute there I thought they had found the missing link.

trollolololo

 

[TJ99]

My human-like brain almost exploded trying to imagine that

Please, we all know there's nothing human-like about you.

 

[be.plato]

trollolololo

Thats unfair

 

[HapticSimian]

But do we know how far away the wall is? So how do we know how close we are....

Its not about trolling

Worms with human brains? LOL, awesome joke for the morning, thanks

Here's sincerely hoping this doesn't degenerate to the same tired merry-go-round around the same tired mulberry bush...

be.plato, you're rejecting a straw man of evolutionary theory. To wit, we - and all organisms contemporary to us - are the wall. We're already touching it.

Rather think about the fields of study around evolution like this, your own collector's series of Marvel comics:



Now imagine some of those books have pages, or even chapters, torn out. You could spend a lifetime searching flea markets and comic book stores for unmolested copies to replace your incomplete examples, but you won't be changing the picture on the spines at all. And so it is with evolution, just exponentially more complex. We know roughly when and how it started, if not exactly, and we know what it's led to. We can even trace back much of the period in-between through genetics, and what we don't know of this vast timespan we can infer. Over and above that we have very, very smart people devoting their lives to finding the missing pages and ensuring they're placed in the right order.

To dismiss evolution in its entirety without understanding the first thing about it is dishonest and disingenuous.

 

[be.plato]

Here's sincerely hoping this doesn't degenerate to the same tired merry-go-round around the same tired mulberry bush...

be.plato, you're rejecting a straw man of evolutionary theory. To wit, we - and all organisms contemporary to us - are the wall. We're already touching it.

Rather think about the fields of study around evolution like this, your own collector's series of Marvel comics:

View attachment 31582

Now imagine some of those books have pages, or even chapters, torn out. You could spend a lifetime searching flea markets and comic book stores for unmolested copies to replace your incomplete examples, but you won't be changing the picture on the spines at all. And so it is with evolution, just exponentially more complex. We know roughly when and how it started, if not exactly, and we know what it's led to. We can even trace back much of the period in-between through genetics, and what we don't know of this vast timespan we can infer. Over and above that we have very, very smart people devoting their lives to finding the missing pages and ensuring they're placed in the right order.

To dismiss evolution in its entirety without understanding the first thing about it is dishonest and disingenuous.

I'm not dismissing anything.

But are we descended from worms?

 

[porchrat]

Thats unfair

Not really.