# Why no freshwater Octopi? **URL:** \ **Category:** Factual Questions\ **Created:** [September 21, 2013, 10:33pm UTC](https://boards.straightdope.com/t/why-no-freshwater-octopi/669397 "2013-09-21T22:33:31Z")\ **Posts on this page:** 20\ **Page:** 1
**Author:** ![pdunderhill](https://avatars.discourse-cdn.com/v4/letter/p/4bbf92/32.png) [@pdunderhill](https://boards.straightdope.com/u/pdunderhill)\ **Post date:** [September 21, 2013, 10:33pm UTC](https://boards.straightdope.com/t/why-no-freshwater-octopi/669397/1 "2013-09-21T22:33:31Z")
Hello good people, fairly short question, answers welcome, Peter ---
**Author:** ![Colibri](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/colibri/32/1841_2.png) [@Colibri](https://boards.straightdope.com/u/Colibri)\ **Post date:** [September 21, 2013, 10:46pm UTC](https://boards.straightdope.com/t/why-no-freshwater-octopi/669397/2 "2013-09-21T22:46:14Z")
I’m not aware of any obvious reason why octopuses and squid have failed to adapt to freshwater. Other mollusks like snails and clams do just fine. The correct English plural, by the way, is octopuses. “Octopi” is pseudo-Latin, the actual Latin plural being _octopodes_. (Octopods is sometimes used in scientific articles.) ---
**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:** [September 21, 2013, 10:50pm UTC](https://boards.straightdope.com/t/why-no-freshwater-octopi/669397/3 "2013-09-21T22:50:07Z")
Octopi, along with Squid, have copper-based blood. This transports oxygen better, under very cold, high-pressure environments. Could fresh water screw this up, somehow? ---
**Author:** ![rat\_avatar](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/rat_avatar/32/255_2.png) [@rat\_avatar](https://boards.straightdope.com/u/rat_avatar)\ **Post date:** [September 21, 2013, 10:51pm UTC](https://boards.straightdope.com/t/why-no-freshwater-octopi/669397/4 "2013-09-21T22:51:56Z")
Cephalopods never developed a sodium pump thus osmosis would try to equalize salt concentrations between its body and the water, this would result in a loss of salt in the body and an increase in water. ---
**Author:** ![Colibri](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/colibri/32/1841_2.png) [@Colibri](https://boards.straightdope.com/u/Colibri)\ **Post date:** [September 21, 2013, 10:56pm UTC](https://boards.straightdope.com/t/why-no-freshwater-octopi/669397/5 "2013-09-21T22:56:32Z")
> [@Bosda\_Di\_Chi\_of\_Tricor](#): > > Octopi, along with Squid, have copper-based blood. > > This transports oxygen better, under very cold, high-pressure environments. > > Could fresh water screw this up, somehow? The same compounds are found in the blood of other mollusks, and it doesn’t seem to be a problem for them. Many octopuses are found in warm shallow water, so their blood chemistry doesn’t limit them to cold deep water. ---
**Author:** ![Chimera](https://avatars.discourse-cdn.com/v4/letter/c/8e8cbc/32.png) [@Chimera](https://boards.straightdope.com/u/Chimera)\ **Post date:** [September 21, 2013, 11:38pm UTC](https://boards.straightdope.com/t/why-no-freshwater-octopi/669397/6 "2013-09-21T23:38:47Z")
I wonder if we can introduce them into Lake Superior and see how they fare? 😉 ---
**Author:** ![njtt](https://avatars.discourse-cdn.com/v4/letter/n/ecd19e/32.png) [@njtt](https://boards.straightdope.com/u/njtt)\ **Post date:** [September 22, 2013, 12:27am UTC](https://boards.straightdope.com/t/why-no-freshwater-octopi/669397/7 "2013-09-22T00:27:36Z")
> [@Colibri](#): > > The correct English plural, by the way, is octopuses. “Octopi” is pseudo-Latin, the actual Latin plural being _octopodes_. I believe that is actually a Greek plural (which is what you want, “octopus” being from Greek, not Latin). ---
**Author:** ![Blue\_Blistering\_Barnacle](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/blue_blistering_barnacle/32/3386_2.png) [@Blue\_Blistering\_Barnacle](https://boards.straightdope.com/u/Blue_Blistering_Barnacle)\ **Post date:** [September 22, 2013, 1:22am UTC](https://boards.straightdope.com/t/why-no-freshwater-octopi/669397/8 "2013-09-22T01:22:37Z")
> [@rat\_avatar](#): > > Cephalopods never developed a sodium pump thus osmosis would try to equalize salt concentrations between its body and the water, this would result in a loss of salt in the body and an increase in water. Is this true? I find it hard to believe,as this is a basic element of cellular machinery. It is essential for nerve conduction (at least in most animals), and the squid axon is used as THE model for nerve conduction. Furthormore, seawater is not iso-osmolar with intracellular fluid, either. ---
**Author:** ![Blue\_Blistering\_Barnacle](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/blue_blistering_barnacle/32/3386_2.png) [@Blue\_Blistering\_Barnacle](https://boards.straightdope.com/u/Blue_Blistering_Barnacle)\ **Post date:** [September 22, 2013, 1:29am UTC](https://boards.straightdope.com/t/why-no-freshwater-octopi/669397/9 "2013-09-22T01:29:53Z")
Sorry, Rat Avatar- I found a cite that supports your statement. Shoulda looked first, before shooting my mouth off. :smack: [http://www.abc.net.au/science/articles/2013/01/16/3670198.htm](http://www.abc.net.au/science/articles/2013/01/16/3670198.htm) “It is probable that they never developed a sodium pump that would help them cope with osmotic change in freshwater,” Norman explains. I still find it incredible. ---
**Author:** ![pdunderhill](https://avatars.discourse-cdn.com/v4/letter/p/4bbf92/32.png) [@pdunderhill](https://boards.straightdope.com/u/pdunderhill)\ **Post date:** [September 22, 2013, 1:59am UTC](https://boards.straightdope.com/t/why-no-freshwater-octopi/669397/10 "2013-09-22T01:59:26Z")
Curious about the plural, my latin and Greek teachers were both ex Oxford. One of their dislikes was Octopuses rather than Octopi. I don’t do ‘dog’ Latin. Still fighting general ignorance etc. So is it an essentially physiological difference with Squid and other eight limbed marine invertebrates? Peter ---
**Author:** ![Napier](https://avatars.discourse-cdn.com/v4/letter/n/ce73a5/32.png) [@Napier](https://boards.straightdope.com/u/Napier)\ **Post date:** [September 22, 2013, 2:01am UTC](https://boards.straightdope.com/t/why-no-freshwater-octopi/669397/11 "2013-09-22T02:01:57Z")
Hydra close enough? ---
**Author:** ![April\_R](https://avatars.discourse-cdn.com/v4/letter/a/3da27b/32.png) [@April\_R](https://boards.straightdope.com/u/April_R)\ **Post date:** [September 22, 2013, 2:05am UTC](https://boards.straightdope.com/t/why-no-freshwater-octopi/669397/12 "2013-09-22T02:05:03Z")
Cephalopods are found in all the oceans of Earth. None of them can tolerate freshwater, but the brief squid, Lolliguncula brevis, found in Chesapeake Bay, may be a notable exception in that it tolerates brackish water Bartol I.K., Mann R., Vecchione M. (2002). “Distribution of the euryhaline squid Lolliguncula brevis in Chesapeake Bay: effects of selected abiotic factors”. Mar. Ecol. Prog. Ser. 226: 235–247. doi:10.3354/meps226235. [http://www.int-res.com/abstracts/meps/v226/p235-247/](http://www.int-res.com/abstracts/meps/v226/p235-247/) Distribution of the euryhaline squid Lolliguncula brevis in Chesapeake Bay: effects of selected abiotic factors ---
**Author:** ![pdunderhill](https://avatars.discourse-cdn.com/v4/letter/p/4bbf92/32.png) [@pdunderhill](https://boards.straightdope.com/u/pdunderhill)\ **Post date:** [September 22, 2013, 2:15am UTC](https://boards.straightdope.com/t/why-no-freshwater-octopi/669397/13 "2013-09-22T02:15:14Z")
Thank you Captain Haddock for your cite, ignorance fought. Deep joy, the best of SDMB, short, sharp and precise. P. ---
**Author:** ![Musicat](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/musicat/32/20189_2.png) [@Musicat](https://boards.straightdope.com/u/Musicat)\ **Post date:** [September 22, 2013, 2:29am UTC](https://boards.straightdope.com/t/why-no-freshwater-octopi/669397/14 "2013-09-22T02:29:17Z")
> [@Chimera](#): > > I wonder if we can introduce them into Lake Superior and see how they fare? 😉 Fedex me one and I’ll introduce it to Lake Michigan. I’ve always wanted to play a prank and scare the shit out of some swimmers. ---
**Author:** ![pdunderhill](https://avatars.discourse-cdn.com/v4/letter/p/4bbf92/32.png) [@pdunderhill](https://boards.straightdope.com/u/pdunderhill)\ **Post date:** [September 22, 2013, 2:45am UTC](https://boards.straightdope.com/t/why-no-freshwater-octopi/669397/15 "2013-09-22T02:45:17Z")
Please can we rename the Brief Squid the ‘Squ’ seems so apt. P ---
**Author:** ![Colibri](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/colibri/32/1841_2.png) [@Colibri](https://boards.straightdope.com/u/Colibri)\ **Post date:** [September 22, 2013, 2:52am UTC](https://boards.straightdope.com/t/why-no-freshwater-octopi/669397/16 "2013-09-22T02:52:45Z")
> [@pdunderhill](#): > > Curious about the plural, > my latin and Greek teachers were both ex Oxford. One of their dislikes was Octopuses rather than Octopi. I don’t do ‘dog’ Latin. No wonder they were “ex” Oxford. 😉 Straight Dope Science Advisory Board member **bibliophage** has written a masterful [staff report on Latin plurals.](http://www.straightdope.com/columns/read/2139/what-is-the-plural-of-penis) > [@](#): > > Yet another group of Latin nouns in -us follow different rules. If you’re still taking notes, these form another subset of the third declension. Typically in these cases the singular does not include the full root… > > Octopus is another of these third declension nouns in Latin, borrowed from Greek. The Latin plural is octopodes, which is acceptable in English, but octopuses (or even octopus) seems more at home in English. The form octopi is quite common in English, but it is pseudo-Latin. It is based on the mistaken belief that octopus was a second-declension noun like fungus. It has made its way into many English dictionaries, but I would not recommend getting tangled up with octopi. It is true that many standard English words have entered the language through mistakes (an apron from a napron, pea from pease, etc.), so octopi may not be totally indefensible. But people who know Latin, admittedly not a large group, will think less of you for using it. ---
**Author:** ![Senegoid](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/senegoid/32/6606_2.png) [@Senegoid](https://boards.straightdope.com/u/Senegoid)\ **Post date:** [September 22, 2013, 8:49am UTC](https://boards.straightdope.com/t/why-no-freshwater-octopi/669397/17 "2013-09-22T08:49:09Z")
If that fresh-water mutant cephalopod you just caught in Lake Michigan has 25.13274 legs (or arms or whatever), it’s an octopi. ---
**Author:** ![The\_Man\_In\_Black](https://avatars.discourse-cdn.com/v4/letter/t/bcef8e/32.png) [@The\_Man\_In\_Black](https://boards.straightdope.com/u/The_Man_In_Black)\ **Post date:** [September 22, 2013, 12:43pm UTC](https://boards.straightdope.com/t/why-no-freshwater-octopi/669397/18 "2013-09-22T12:43:18Z")
> [@Bosda\_Di\_Chi\_of\_Tricor](#): > > Octopi, along with Squid, have copper-based blood. Are they Vulcans? ---
**Author:** ![pulykamell](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/pulykamell/32/3166_2.png) [@pulykamell](https://boards.straightdope.com/u/pulykamell)\ **Post date:** [September 22, 2013, 2:48pm UTC](https://boards.straightdope.com/t/why-no-freshwater-octopi/669397/19 "2013-09-22T14:48:55Z")
> [@Colibri](#): > > No wonder they were “ex” Oxford. 😉 > > Straight Dope Science Advisory Board member **bibliophage** has written a masterful [staff report on Latin plurals.](http://www.straightdope.com/columns/read/2139/what-is-the-plural-of-penis) I’m not sure that’s entirely right. From what I can gather, _oktṓpodes (ὀκτώποδες)_ is the _Greek_ plural. Were the word native to Latin, the singular would be _octōpēs_ and the plural would therefore be _octōpedes_. (Another common Latin plural “mistake” is the usually jocular use of “penii” for “penises,” where “penes” would be the correct Latin plural.) At any rate, I think “octopi” or “octopodes” or “octopedes” all sound dumb in English and the plural should be the normal “octopuses” (or perhaps I can allow for just “octopus,” but I’d prefer to keep it regular.) Also, I didn’t realize this, but “octopodes” is not pronounced as I thought it would be (that is, “octo” + “podes.”) It’s something like “ock-TOP-uh-deez,” which sounds like something you’d order at a Greek restaurant. (And, actually, Greek style octopus is quite good.) ---
**Author:** ![What\_Exit](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/what_exit/32/10652_2.png) [@What\_Exit](https://boards.straightdope.com/u/What_Exit)\ **Post date:** [September 22, 2013, 3:24pm UTC](https://boards.straightdope.com/t/why-no-freshwater-octopi/669397/20 "2013-09-22T15:24:17Z")
[There is a thread on the Octopi debate from 2006](http://boards.straightdope.com/sdmb/showthread.php?t=384079&highlight=Octopi). Octopi is a legit version for English. [Next page](https://boards.straightdope.com/t/why-no-freshwater-octopi/669397.md?page=2)