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We are all individuals
April 18, 2013 9:57 PM   Subscribe

Siphonophores are colonial organisms—they are composed of zoöids, specialised individuals that live together collectively, each performing a function that is essential to the other members of the colony. One well-known example is the Portuguese man o' war, which is actually composed of four separate types of zoöids despite resembling the individual organism otherwise known as the jellyfish. Turns out they are also remarkably beautiful.

Aaron Ansarov also has more extensive galleries of the zoöids, and has also photographed ordinary backyard denizens in amazing detail. (Warning for arachnophobes: includes spiders.)
posted by Athanassiel (7 comments total) 28 users marked this as a favorite

 
I'm not!

Seriously, though, this is some really cool stuff.
posted by Zimboe Metamonkey at 10:35 PM on April 18, 2013 [3 favorites]


Evolutionarily these guys are fascinating because they straddle the line between a differentiated colony and a single organism with multiple organs.

I find them fascinating for a different reason: they have two entirely different forms which alternate by generation.

First, there are polyps. These live attached to rocks, and they produce medusae asexually by budding.

Second are the medusae, the jellyfish. They float freely and reproduce sexually, creating larval polyps who then look for a rock to hook onto.
posted by Chocolate Pickle at 11:23 PM on April 18, 2013 [5 favorites]


I think I read somewhere that there's a type of these that can revert from the medusae back to the polyp stage, theoretically giving it life unending.
posted by dazed_one at 3:07 AM on April 19, 2013


Man, biology is so frickin' weird and awesome

On top of the siphonophores being "multi-organism organisms" as described in the OP, they're also, like all other life-forms except bacteria and certain other germs, endosymbiotic with another ancient life-form that long ago became incorporated into their basic cell structure. Mitochondria first appeared hundreds of millions of years ago when a pair of cells united instead of consuming one another.

In that sense, all life-forms that use mitochondria have "split personalities".

In addition, humans have retroviruses incorporated into our DNA to such an extent that we wouldn't be what we think of as "human" without them. Almost a tenth of our DNA is ancient viruses. "One virus protein, syncytin, is essential for our being born at all."

I really like this from the OP:
Siphonophores challenge us to think about what we mean when we call something an individual, a concept that we usually think of as being quite straightforward. Is a single zooid or an entire colony the siphonophore “individual”? The answer is that you have to specify what features you are interested in before you can expect a meaningful answer. ....It should be noted that an Amoeba, which is a solitary cell, would have much the same trouble contemplating the individuality of a human. Humans function as ecological, behavioral, and evolutionary individuals. But they are made up of many cells. So is the entire human an individual, or are each of the cells individuals? We are in the same conundrum as the Ameoba because individuality has arisen multiple times in evolution, often subsuming units that are (or were, depending on how you look at it) themselves individuals.
It's another reminder that the circles that we draw around things to make sense of the world are frequently arbitrary and that the universe is weirder than we primates can wrap our heads around. Though we normally think a thing must be one thing or another thing, reality has more complexity than we're able to neatly taxonomize and calculate. The fact that many organisms are either individuals or groups of organisms, depending on how you look at it, reminds me of the way light is either a wave or particle depending on how you look at it.

So badass
posted by Sleeper at 4:27 AM on April 19, 2013 [3 favorites]


First, there are polyps. These live attached to rocks, and they produce medusae asexually by budding.

Second are the medusae, the jellyfish. They float freely and reproduce sexually, creating larval polyps who then look for a rock to hook onto.
posted by Chocolate Pickle


I love this poem.
posted by Lipstick Thespian at 5:24 AM on April 19, 2013 [1 favorite]


dazed_one, there's the immortal jellyfish (Turritopsis nutricula), and it's quite pretty too.
posted by Athanassiel at 6:07 AM on April 19, 2013


Horray for zoöids!
Is it wrong to want a peanutbutterfish to go with my jellyfish?
posted by BlueHorse at 2:25 PM on April 19, 2013


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