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> All life on Earth is classified within three domains — bacteria, archaea and eukarya — with eukarya containing all multicellular organisms Single cell eukary

by mmooss 2y ago

> All life on Earth is classified within three domains — bacteria, archaea and eukarya — with eukarya containing all multicellular organisms Single cell eukaryotes also exist. Is it strictly true that there are no multicellular prokaryotes (what they call bacteria) or archaea? No exceptions at all?

dragonwriter 2y ago
> Single cell eukaryotes also exist. Yes, "with eukarya containing all multicellular organisms" does not mean "all eukarya are multicellular organisms" it means "multicellular organisms are a subset of eukarya". > Is it strictly true that there are no multicellular prokaryotes (what they call bacteria) or archaea? First off, "prokaryotes (what they call bacteria)" is incorrect. Both archaea and bacteria, in the three-domain model referenced in the article, are prokaryotes. Second, correct, everything understood as a multicellular organism -- as distinct from colonies of unicellular organisms -- is composed of cells with nuclei, classified in eukarya in the three-domain model. (There is a newer proposed two-domain model which disposes with Eukarya as a top-level domain, folding it under Archaea; in that model, clearly, there are multicellular Archaea.)
- mmooss 2y ago
  > Both archaea and bacteria, in the three-domain model referenced in the article, are prokaryotes. I suppose it depends on which model you use, and as discussed they seem to vary and be in flux right now, but the three domain model I learned was prokaryotes, archaea, and eukaryotes - the first two being different domains. > Yes, "with eukarya containing all multicellular organisms" does not mean "all eukarya are multicellular organisms" it means "multicellular organisms are a subset of eukarya". We agree. I don't grasp your point?
  - xdavidliu 2y ago
    > We agree. I don't grasp your point? your original comment didn't refute the quote, but one needs to squint hard to see that you didn't refute it.
    - mmooss 2y ago
      I wasn't trying to refute it; I was adding information: The quote didn't mention or imply that there are also single-cell eukaryotes, so I added that detail. Not everything is an argument or attack.
      - xdavidliu 2y ago
        I know that you weren't trying to refute it, and I know that it's not an argument or attack. > with eukarya containing all multicellular organisms Single cell eukaryotes also exist My point is that your statement here looks like a refutation to most, even though I know you did not intend it to be.
        mmooss 2y ago
        I see. Communication is tricky.
zdragnar 2y ago
Cyanobacteria are an example of prokaryotes that, while not truly multicellular, may at times exhibit similar behavior. They can form colonies and, within groups that share walls, specialize into different functions such as photosynthesis or nitrogen fixing behavior. This enables the colony to adapt to changing conditions that, while still made up of individual organisms, collectively appear to function similarly to a single multicellular one. With that said, there aren't any examples of truly multicellular organisms within either domain. Just as an ant colony is not a single organism, cyanobacteria colony specializations are not examples of organs.
danwills 2y ago
I think prokaryotic bacteria can form biofilms which seems like one step on the road to multicellularity, but that's more like a community, and iiuc most biofilms these days at least contain eukaryotic yeasts. I don't know of any actually-properly-multicellular prokaryotes, but maybe I need to read up?

by mmooss 2y ago

dragonwriter 2y ago

> Single cell eukaryotes also exist. Yes, "with eukarya containing all multicellular organisms" does not mean "all eukarya are multicellular organisms" it means "multicellular organisms are a subset of eukarya". > Is it strictly true that there are no multicellular prokaryotes (what they call bacteria) or archaea? First off, "prokaryotes (what they call bacteria)" is incorrect. Both archaea and bacteria, in the three-domain model referenced in the article, are prokaryotes. Second, correct, everything understood as a multicellular organism -- as distinct from colonies of unicellular organisms -- is composed of cells with nuclei, classified in eukarya in the three-domain model. (There is a newer proposed two-domain model which disposes with Eukarya as a top-level domain, folding it under Archaea; in that model, clearly, there are multicellular Archaea.)

mmooss 2y ago
> Both archaea and bacteria, in the three-domain model referenced in the article, are prokaryotes. I suppose it depends on which model you use, and as discussed they seem to vary and be in flux right now, but the three domain model I learned was prokaryotes, archaea, and eukaryotes - the first two being different domains. > Yes, "with eukarya containing all multicellular organisms" does not mean "all eukarya are multicellular organisms" it means "multicellular organisms are a subset of eukarya". We agree. I don't grasp your point?
- xdavidliu 2y ago
  > We agree. I don't grasp your point? your original comment didn't refute the quote, but one needs to squint hard to see that you didn't refute it.
  - mmooss 2y ago
    I wasn't trying to refute it; I was adding information: The quote didn't mention or imply that there are also single-cell eukaryotes, so I added that detail. Not everything is an argument or attack.
    - xdavidliu 2y ago
      I know that you weren't trying to refute it, and I know that it's not an argument or attack. > with eukarya containing all multicellular organisms Single cell eukaryotes also exist My point is that your statement here looks like a refutation to most, even though I know you did not intend it to be.
      - mmooss 2y ago
        I see. Communication is tricky.

zdragnar 2y ago

Cyanobacteria are an example of prokaryotes that, while not truly multicellular, may at times exhibit similar behavior. They can form colonies and, within groups that share walls, specialize into different functions such as photosynthesis or nitrogen fixing behavior. This enables the colony to adapt to changing conditions that, while still made up of individual organisms, collectively appear to function similarly to a single multicellular one. With that said, there aren't any examples of truly multicellular organisms within either domain. Just as an ant colony is not a single organism, cyanobacteria colony specializations are not examples of organs.

danwills 2y ago

I think prokaryotic bacteria can form biofilms which seems like one step on the road to multicellularity, but that's more like a community, and iiuc most biofilms these days at least contain eukaryotic yeasts. I don't know of any actually-properly-multicellular prokaryotes, but maybe I need to read up?