Expert: Walter Hintz - 1/21/2007

Question
Why is it not possible to really have a unicellular organism big enough to engulf small children and dogs?
Like the blob.

Answer
Hi Chastity;  This is a good question.  A unicellular organism that could engulf a large animal would in itself have to be very large.  The problem is that Individual cells are limited in size by what we call the scale effect.  To stay alive a cell must take in nutrients and expel wastes.  This is done through the cell surface area: The larger the cell the greater the needs for nutrients but the less surface area there is to make the exchanges so cells have to remain small.  There is also a problem of support.  Multi cellular organisms need some king of a skeleton to support the mass.