# Ameobas the size of a quarter? **URL:** \ **Category:** Factual Questions\ **Created:** [July 30, 2002, 3:30am UTC](https://boards.straightdope.com/t/ameobas-the-size-of-a-quarter/121480 "2002-07-30T03:30:56Z")\ **Posts on this page:** 13\ **Page:** 1
**Author:** ![Pythagoras](https://avatars.discourse-cdn.com/v4/letter/p/48db29/32.png) [@Pythagoras](https://boards.straightdope.com/u/Pythagoras)\ **Post date:** [July 30, 2002, 3:30am UTC](https://boards.straightdope.com/t/ameobas-the-size-of-a-quarter/121480/1 "2002-07-30T03:30:56Z")
I thought I recall some one telling me that there was a species of ameoba in the amazon or some such that was the size of a quarter. (fricken huge for an ameoba). Is this true? Is it even possible? ---
**Author:** ![Ranchoth](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/ranchoth/32/1066_2.png) [@Ranchoth](https://boards.straightdope.com/u/Ranchoth)\ **Post date:** [July 30, 2002, 3:43am UTC](https://boards.straightdope.com/t/ameobas-the-size-of-a-quarter/121480/2 "2002-07-30T03:43:34Z")
Well, all I can tell you is that I remember seeing a picture (In National Geographic) of a group of about 4 or 5 bacteria that barely squeezed onto the head of a pin. In other words, _almost_ visible to the naked eye. 'Don’t know if there are any bigger critters than that, or even if the creatures pictured were “true” single-celled organisms. Ranchoth ---
**Author:** ![astro](https://avatars.discourse-cdn.com/v4/letter/a/9dc877/32.png) [@astro](https://boards.straightdope.com/u/astro)\ **Post date:** [July 30, 2002, 4:01am UTC](https://boards.straightdope.com/t/ameobas-the-size-of-a-quarter/121480/3 "2002-07-30T04:01:28Z")
> [@](#): > > \*Originally posted by Pythagoras \* > \*\*I thought I recall some one telling me that there was a species of ameoba in the amazon or some such that was the size of a quarter. (fricken huge for an ameoba). Is this true? Is it even possible? \*\* [Xenophyophores - the giants of the protozoan world - 10cm to 25cm single-celled ‘monsters’ live in the depths of our oceans!]([http://www.microscopy-uk.org.uk/mag/artnov98/xeno1.html](http://www.microscopy-uk.org.uk/mag/artnov98/xeno1.html) ) > [@](#): > > How would you answer the question ‘What is the world’s largest protozoan?’. In freshwater, Stentor can grow to ca. 3mm and Pelomyxa can grow to ca. 5mm, although I’ve never had the fortune as an amateur pond-dipper to find a specimen of the latter. My concept of the largest is of the order of a few millimetres (see footnote 1), but a news item in ‘New Scientist’ recently (ref. 1) rapidly changed my view by a factor of twenty - yes, we are talking about 10 cm single-celled ‘monsters’! > > Apparently UK scientists have discovered 1km down in the North Atlantic what is believed to be the largest specimen of a single-celled organism ever found. It is a globular Xenophyophore 10 cm across of the species Syringammina fragillissima. (See footnote 2). The news item is brief but ref. 2 has a good section on the phylum with illustrations. If a single dimension is taken as the criterion for the largest, apparently even Syringammina would be dwarfed by a 1mm thick disc-shaped Stannophyllum specimen which was found to be 25 cm in diameter. ---
**Author:** ![samclem](https://avatars.discourse-cdn.com/v4/letter/s/a9a28c/32.png) [@samclem](https://boards.straightdope.com/u/samclem)\ **Post date:** [July 30, 2002, 4:10am UTC](https://boards.straightdope.com/t/ameobas-the-size-of-a-quarter/121480/4 "2002-07-30T04:10:09Z")
In layman’s terms, could you suggest what this means for us humans as a species? Should I cash in my 401K and party like there’s no tomorrow? ---
**Author:** ![Urban\_Ranger](https://avatars.discourse-cdn.com/v4/letter/u/e9c0ed/32.png) [@Urban\_Ranger](https://boards.straightdope.com/u/Urban_Ranger)\ **Post date:** [July 30, 2002, 7:27am UTC](https://boards.straightdope.com/t/ameobas-the-size-of-a-quarter/121480/5 "2002-07-30T07:27:54Z")
The link doesn’t work ---
**Author:** ![Mangetout](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/mangetout/32/19_2.png) [@Mangetout](https://boards.straightdope.com/u/Mangetout)\ **Post date:** [July 30, 2002, 7:42am UTC](https://boards.straightdope.com/t/ameobas-the-size-of-a-quarter/121480/6 "2002-07-30T07:42:44Z")
[Fixed link](http://www.microscopy-uk.org.uk/mag/artnov98/xeno1.html) ---
**Author:** ![Tars\_Tarkas](https://avatars.discourse-cdn.com/v4/letter/t/6a8cbe/32.png) [@Tars\_Tarkas](https://boards.straightdope.com/u/Tars_Tarkas)\ **Post date:** [July 30, 2002, 7:43am UTC](https://boards.straightdope.com/t/ameobas-the-size-of-a-quarter/121480/7 "2002-07-30T07:43:18Z")
i’ll fix it!!! [http://www.microscopy-uk.org.uk/mag/artnov98/xeno1.html](http://www.microscopy-uk.org.uk/mag/artnov98/xeno1.html) Did i earn a cookie? An Ameba cookie? ---
**Author:** ![Bosda\_Di\_Chi\_of\_Tricor](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/bosda_di_chi_of_tricor/32/16845_2.png) [@Bosda\_Di\_Chi\_of\_Tricor](https://boards.straightdope.com/u/Bosda_Di_Chi_of_Tricor)\ **Post date:** [July 30, 2002, 12:06pm UTC](https://boards.straightdope.com/t/ameobas-the-size-of-a-quarter/121480/8 "2002-07-30T12:06:07Z")
Pictures, anybody? ☹ ---
**Author:** ![majinborg](https://avatars.discourse-cdn.com/v4/letter/m/db5fbb/32.png) [@majinborg](https://boards.straightdope.com/u/majinborg)\ **Post date:** [July 30, 2002, 1:17pm UTC](https://boards.straightdope.com/t/ameobas-the-size-of-a-quarter/121480/9 "2002-07-30T13:17:55Z")
As far as I learned in SAT II Bio (9th grade), single-celled organisms could not grow past a certain size, a size far less than any coin. This is because, so I learned, of diffusion. A single cell does not have a circulatory system composed of tissue, lest it lose its single-cell-hood. Therefore nutrients must diffuse through the cell naturally. Now, suppose we start with a normal-sized amoeba, then increase its volume. We soon find that its surface area (the workable area through which it must absorb all its nutrients) does not increase as fast as its volume does. Therefore, there swiftly comes a point where the nutrients simply do not diffuse fast enough to keep the cell alive. We did a nifty demonstration of this in the aforementioned Bio class using agar cubes of various sizes and a diffusing dye. ---
**Author:** ![Squink](https://avatars.discourse-cdn.com/v4/letter/s/b5e925/32.png) [@Squink](https://boards.straightdope.com/u/Squink)\ **Post date:** [July 30, 2002, 1:38pm UTC](https://boards.straightdope.com/t/ameobas-the-size-of-a-quarter/121480/10 "2002-07-30T13:38:00Z")
[http://seawifs.gsfc.nasa.gov/OCEAN\_PLANET/IMAGES/G-550.gif](http://seawifs.gsfc.nasa.gov/OCEAN_PLANET/IMAGES/G-550.gif) [http://www.soc.soton.ac.uk/CHD/Sediments/seds\_afen/xeno\_2.jpg?99,123](http://www.soc.soton.ac.uk/CHD/Sediments/seds_afen/xeno_2.jpg?99,123) [http://www.ecology.com/expeditions/deep-east-producers-logs/9-27-28-01/](http://www.ecology.com/expeditions/deep-east-producers-logs/9-27-28-01/) ---
**Author:** ![Mac\_Guffin](https://avatars.discourse-cdn.com/v4/letter/m/2bfe46/32.png) [@Mac\_Guffin](https://boards.straightdope.com/u/Mac_Guffin)\ **Post date:** [July 30, 2002, 3:22pm UTC](https://boards.straightdope.com/t/ameobas-the-size-of-a-quarter/121480/11 "2002-07-30T15:22:36Z")
The second picture looks like it’s grinning an evil grin… ---
**Author:** ![Polycarp](https://avatars.discourse-cdn.com/v4/letter/p/82dd89/32.png) [@Polycarp](https://boards.straightdope.com/u/Polycarp)\ **Post date:** [July 30, 2002, 3:29pm UTC](https://boards.straightdope.com/t/ameobas-the-size-of-a-quarter/121480/12 "2002-07-30T15:29:38Z")
**majinbourg** , many protozoans have interior pathways – the details I’m hazy on; this board needs a good cytologist! – that improve the flow of nutrients, dissolved oxygen, wastes, etc. So the objection you raise applies only to the abstract “it’s nothing but a nucleus and undifferentiated cytoplasm” single-celled critter that is a simplification rather than an actuality. (Much like why “bumblebees can’t fly according to physics” is wrong.) ---
**Author:** ![malaka](https://avatars.discourse-cdn.com/v4/letter/m/ecc23a/32.png) [@malaka](https://boards.straightdope.com/u/malaka)\ **Post date:** [July 30, 2002, 4:15pm UTC](https://boards.straightdope.com/t/ameobas-the-size-of-a-quarter/121480/13 "2002-07-30T16:15:31Z")
> [@](#): > > \*Originally posted by Bosda Di’Chi of Tricor \* > \*\*Pictures, anybody? ☹ \*\* > **[Scifi.com](https://www.syfy.com/scifi/startrek/episodes/48.html)** > > Visit Syfy.com