• Question: *Star question* How big can a cell get? - OrionW, live chat

    Asked by modlucia on 7 Jul 2020.
    • Photo: Kelly Charniga

      Kelly Charniga answered on 7 Jul 2020: last edited 7 Jul 2020 12:52 am


      Species of Caulerpa, a type of green algae, are considered the largest known single-celled organisms in the world. Although each one is a single large cell, they have multiple nuclei and structures that are similar to roots, stems, and leaves. Caulerpa can be found in the Atlantic, Indian, and Pacific Oceans and can grow up to 30 cm long.

      If we’re talking about humans, the largest cell in the human body is the egg (ovum). It is about 0.1 mm wide, or about the same thickness as a strand of hair.

    • Photo: Nina Rzechorzek

      Nina Rzechorzek answered on 7 Jul 2020: last edited 7 Jul 2020 1:49 am


      Fabulous question OrionW – focussing on the human body – the longest cell type is a cell belonging to the nervous system – the motor neuron; particularly the motor neurons that tell the muscles in your legs to contract and thus allow leg movement. The cell bodies of these motor neurons sit within the lower end of the spinal cord and they send long processes (axons) out to the periphery which together form the sciatic nerve. These axons can be over a metre in length as they reach the muscles of your big toe! They will be even longer in tall animals with long legs (giraffes) and even longer in the largest mammals on earth (the Blue whale). Based on cell body diameter however, I think the ‘fattest’ cell in the human body is the female egg/oocyte/ovum which is about 0.1mm across and can just about be seen by the naked eye without a microscope!

    • Photo: Gulnar Abdullayeva

      Gulnar Abdullayeva answered on 7 Jul 2020:


      The size of a cell is controlled by many factors — growth factors, cell division, nutrition, environmental agents, protein production, and autophagy (a way of cleaning out damaged cells to regenerate newer cells). It varies among different organisms depending on where it originates from and what its function. 
      In plants,
      1. Ovules of Cycas is the largest plant cell in multicellular plants, with 6-7 cm in diameter.
      2. A unicellular aquatic alga called Caulerpa taxifolia is the world’s largest single-celled organism, which can grow to a length of six to twelve inches. 
      In animal kingdom, the largest recorded egg is from a whale shark and was 30 cm × 14 cm × 9 cm in size. The ostrich has the largest laid egg among any living bird. One ostrich egg is roughly equal to the size of 24 chicken eggs.
      In human body, nerve cells or neurons are considered the longest cells, which can be up to a meter long, depending on the height of the person. They reach from the base of the spinal cord to the foot, by sending signals from one part of the body to another. The largest cell (by volume) in the human body is the female egg/ovum, which measures approximately 0.1 mm in diameter. 
      Hope this answers your question. Thank you.

    • Photo: Melanie Krause

      Melanie Krause answered on 7 Jul 2020:


      Hi 🙂
      Unfertilised eggs are single cells and as such the biggest egg we know is also the biggest cell… and that is an ostrich egg! I actually have a blown out one at home (in South Africa they get painted and are popular souvenirs for tourists) and its huge.. to think that thats one cell is pretty impressive 😉

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