Min # of cells in a multicellular organism

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Discussion Overview

The discussion revolves around the theoretical minimum number of cells required for an organism to be classified as multicellular, as well as inquiries into the smallest known multicellular organisms. Participants explore definitions, examples, and the complexities of categorizing organisms based on cell count and structure.

Discussion Character

  • Debate/contested
  • Conceptual clarification

Main Points Raised

  • Some participants suggest that a fertilized egg or zygote could be considered a multicellular organism, potentially allowing for a minimum of one cell.
  • Others argue that a multicellular organism must consist of more than one cell and be self-sustaining, emphasizing the need for clarity in definitions.
  • One participant notes that there are organisms, such as certain green algae, that may challenge traditional definitions by having very few cells, including examples of binucleate organisms.
  • There is mention of the complexity of categorizing organisms, with references to slime molds and colonial organisms like Volvox, which complicate the understanding of multicellularity.

Areas of Agreement / Disagreement

Participants do not reach a consensus on the definition of multicellularity or the minimum number of cells required, with multiple competing views and examples presented throughout the discussion.

Contextual Notes

The discussion highlights the ambiguity in defining multicellular organisms and the potential for exceptions that challenge conventional categorizations. There are unresolved issues regarding the definitions and classifications of organisms based on cell count.

farful
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Given a multicellular organism, what is the theoretic minimum amount of cells it can have?

Theory aside, what is the smallest known mulitcellular organism?
Furthermore, anyone know of any links that show a table of organism and # of cells?

Much thanks!
 
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A fertilized egg or zygote can become multicellular as it matures. So by your definitions the answer can be 'one'.
 
jim mcnamara said:
A fertilized egg or zygote can become multicellular as it matures. So by your definitions the answer can be 'one'.

I left the definition of "multicellular organism" to be vague, hoping it was understood. I'll keep the definition vague (as it's not easy to define) and say it needs to be MORE than one cell, self-sustaining, # of cells in a matured organism, colonies are not organisms, and be careful with symbiosis as well. I suppose I could keep clarifying as people give more answers.
 
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Look, unless you completely definite there are no good answers. And maybe not even then. Here's why - for almost any 'condition' you care to describe there is almost always an organism that defies categorization that way - and others that fit the condition.

Plants and wee beasties do not fit our preconceived notions of how they are supposed to be.

Before this gets hard to deal with - there are green algae that may have two cells when they are mature. Desmids, like some Xantidium spp., are classified by some older authors as being two cells because they can be binucleate. Some Dinoflaellates are binucleate but do not look like desmids, cleaved in half, so they are typically categorized as being single celled.

The real point is: our human-centric categories do not fit all living things. Period. Check out slime molds on Wikipedia if you want a real headache.

Also - multicellular sometimes is taken to mean an organism with many cells made of differentiated cells; different types of cells & tissues , performing different tasks, e.g., root, cortex, mesophyll, epidermis. I think this is what you are confusing with colonial organisms.

The definition I used for the answers above is what you implied - simply any organism that lives life as more than one cell. Colonial organisms. My favorite is Volvox. Check it out.
 

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