Why do some biologists refer to single-celled organisms such as Amoeba and Paramecium as acellular (i.e., without cells) rather than unicellular (i.e., one cell)?

  • 2
    $\begingroup$ Can you point us to an example of this? $\endgroup$
    – Alan Boyd
    Oct 11, 2012 at 12:52

1 Answer 1


From Wikipedia:

Some biologists refer to wholly syncytial organisms as "acellular" because their bodies contain multiple nuclei which are not separated by cell walls.

As Albano pointed out, "cell walls" should probably be "cell membranes".

Paramecium and some types of amoeba like the Chaos genus have multiple nuclei so they fall under this definition.

  • $\begingroup$ Our own cells are not separated by cell walls either. This is an error in Wikipedia. It should probably read "cell membranes". $\endgroup$
    – S. Albano
    Oct 11, 2012 at 6:17
  • $\begingroup$ @S.Albano yes you are right it should probably be cellular membranes. $\endgroup$
    – Bitwise
    Oct 11, 2012 at 13:22
  • $\begingroup$ @Bitwise, I stand corrected thank you. Comment removed to avoid confusion. $\endgroup$
    – terdon
    Oct 11, 2012 at 13:49

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