# Can any land animals survive off of salt water? **URL:** \ **Category:** Factual Questions\ **Created:** [May 30, 2007, 4:18am UTC](https://boards.straightdope.com/t/can-any-land-animals-survive-off-of-salt-water/406029 "2007-05-30T04:18:00Z")\ **Posts on this page:** 9\ **Page:** 1
**Author:** ![SenorBeef](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/senorbeef/32/2220_2.png) [@SenorBeef](https://boards.straightdope.com/u/SenorBeef)\ **Post date:** [May 30, 2007, 4:18am UTC](https://boards.straightdope.com/t/can-any-land-animals-survive-off-of-salt-water/406029/1 "2007-05-30T04:18:00Z")
It would seem that being able to drink sea water would allow a coastal animal of some sort exist in ecological niches where there isn’t sufficient fresh water to support them, and yet I can’t recall ever reading about a land based mammal that could survive off of salt water. I’m guessing there are amphibians that fit this description, but they’re not truly land animals. If there are no such animals, why not? Is there something inherent about land animal physiology? It seems to me that as whales and dolphins can do it, there’s nothing inherently limiting about mammalian physiology. Is the presence of fresh water in coastal regions common enough that this adaptation would be of limited usefulness? ---
**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:** [May 30, 2007, 4:34am UTC](https://boards.straightdope.com/t/can-any-land-animals-survive-off-of-salt-water/406029/2 "2007-05-30T04:34:22Z")
[QUOTE=SenorBeef] It would seem that being able to drink sea water would allow a coastal animal of some sort exist in ecological niches where there isn’t sufficient fresh water to support them, and yet I can’t recall ever reading about a land based mammal that could survive off of salt water. [/quote] Camels are pretty tolerant of drinking salty water, and at least one population of Bactrian camels seems able to survive by drinking from salty inland springs. [http://www.arkive.org/species/GES/mammals/Camelus\_bactrianus/more\_info.html](http://www.arkive.org/species/GES/mammals/Camelus_bactrianus/more_info.html) > [@](#): > > I’m guessing there are amphibians that fit this description, but they’re not truly land animals. Amphibians (frogs, toads, salamanders, etc.) are actually very intolerant of salt water. Few can tolerate even brackish water. > [@](#): > > If there are no such animals, why not? Is there something inherent about land animal physiology? It seems to me that as whales and dolphins can do it, there’s nothing inherently limiting about mammalian physiology. It’s actually not entirely clear that most marine mammals actually do drink all that much seawater. They get their water from their food, rather than by drinking. [http://www.sciam.com/askexpert\_question.cfm?articleID=000DBE8D-633A-1C72-9EB7809EC588F2D7](http://www.sciam.com/askexpert_question.cfm?articleID=000DBE8D-633A-1C72-9EB7809EC588F2D7) > [@](#): > > Although some marine mammals are known to drink seawater at least on occasion, it is not well established that they routinely do so. They have other options: sea-dwelling mammals can get water through their food, and they can produce it internally from the metabolic breakdown of food (water is one of the by-products of carbohydrate and fat metabolism). > [@](#): > > Is the presence of fresh water in coastal regions common enough that this adaptation would be of limited usefulness? I would guess that this is part of the answer too. ---
**Author:** ![John\_Mace](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/john_mace/32/185_2.png) [@John\_Mace](https://boards.straightdope.com/u/John_Mace)\ **Post date:** [May 30, 2007, 4:35am UTC](https://boards.straightdope.com/t/can-any-land-animals-survive-off-of-salt-water/406029/3 "2007-05-30T04:35:41Z")
> [@](#): > > It seems to me that as whales and dolphins can do it… Cetaceans don’t drink salt water. They get water from their food. ---
**Author:** ![Sal\_Ammoniac](https://avatars.discourse-cdn.com/v4/letter/s/8dc957/32.png) [@Sal\_Ammoniac](https://boards.straightdope.com/u/Sal_Ammoniac)\ **Post date:** [May 30, 2007, 2:25pm UTC](https://boards.straightdope.com/t/can-any-land-animals-survive-off-of-salt-water/406029/4 "2007-05-30T14:25:32Z")
But aren’t there lots of mammals that don’t actually drink anything? I think there are certain rodents that live in desert climates that don’t really drink. I don’t think sea otters drink either. Drinking… it’s overrated! ---
**Author:** ![David\_Simmons](https://avatars.discourse-cdn.com/v4/letter/d/9de053/32.png) [@David\_Simmons](https://boards.straightdope.com/u/David_Simmons)\ **Post date:** [May 30, 2007, 3:50pm UTC](https://boards.straightdope.com/t/can-any-land-animals-survive-off-of-salt-water/406029/5 "2007-05-30T15:50:31Z")
[QUOTE=Sal Ammoniac] But aren’t there lots of mammals that don’t actually drink anything? I think there are certain rodents that live in desert climates that don’t really drink. I don’t think sea otters drink either. Drinking… it’s overrated! [/QUOTE] [Kangaroo rats](http://www.desertusa.com/aug96/du_krat.html)rarely drink water. It’s possible that some of them go their whole life without drinking any water. They are able to recover\* enough water from their food, either the water of hydration bound up in the molecules of the food, or the free water that’s in the seeds. They also have elaborate water saving mechanisms in their makeup and don’t require all that much water because they lose so little. - The cite says they convert some of their food to water but that’s misleading. The water is already there, they just are able to recover it. ---
**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:** [May 30, 2007, 5:00pm UTC](https://boards.straightdope.com/t/can-any-land-animals-survive-off-of-salt-water/406029/6 "2007-05-30T17:00:49Z")
[QUOTE=David Simmons] It’s possible that some of them go their whole life without drinking any water. They are able to recover\* enough water from their food, either the water of hydration bound up in the molecules of the food, or the free water that’s in the seeds. They also have elaborate water saving mechanisms in their makeup and don’t require all that much water because they lose so little. - The cite says they convert some of their food to water but that’s misleading. The water is already there, they just are able to recover it. [/QUOTE] Actually, they really do convert their food partly to water, but then pretty much all animals do. This is “metabolic water,” and is different from water of hydration or free water that’s in the seeds. [Water of hydration](http://www.answers.com/topic/water-of-hydration) > [@](#): > > Water chemically combined with a substance in such a way that it can be removed, as by heating, without substantially changing the chemical composition of the substance. “Metabolic water” refers to the water created by the oxidation of carbohydrates and other foods through respiration and involves the chemical breakdown of the original compounds. This water was not previously present in the food in the form of H20. ---
**Author:** ![David\_Simmons](https://avatars.discourse-cdn.com/v4/letter/d/9de053/32.png) [@David\_Simmons](https://boards.straightdope.com/u/David_Simmons)\ **Post date:** [May 30, 2007, 5:12pm UTC](https://boards.straightdope.com/t/can-any-land-animals-survive-off-of-salt-water/406029/7 "2007-05-30T17:12:30Z")
[QUOTE=Colibri] Actually, they really do convert their food partly to water, but then pretty much all animals do. This is “metabolic water,” and is different from water of hydration or free water that’s in the seeds. [Water of hydration](http://www.answers.com/topic/water-of-hydration) “Metabolic water” refers to the water created by the oxidation of carbohydrates and other foods through respiration and involves the chemical breakdown of the original compounds. This water was not previously present in the food in the form of H20. [/QUOTE] Live and learn. Thanks. As a sidenote, kangaroo rats are quarrelsome little devils. Very territorial and if two of them are in an area they are in a fight. Suppose their bad temper is because they are always thirsty? 🙂 ---
**Author:** ![Sapo](https://avatars.discourse-cdn.com/v4/letter/s/ec9cab/32.png) [@Sapo](https://boards.straightdope.com/u/Sapo)\ **Post date:** [May 30, 2007, 8:21pm UTC](https://boards.straightdope.com/t/can-any-land-animals-survive-off-of-salt-water/406029/8 "2007-05-30T20:21:50Z")
don’t ducks and geese drink salt 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:** [May 30, 2007, 8:46pm UTC](https://boards.straightdope.com/t/can-any-land-animals-survive-off-of-salt-water/406029/9 "2007-05-30T20:46:15Z")
[QUOTE=Sapo] don’t ducks and geese drink salt water? [/QUOTE] Yes. Birds and reptiles have special salt glands located over the eyes. A salt solution is excreted through the nostrils. Sea birds in general possess such glands. In species such as some ducks which may switch between freshwater and marine habitats at different times during the year, the gland will hypertrophy or regress depending on whether it is being used or not. Birds and reptiles have an advantage over mammals because their main nitrogenous excretory product is uric acid instead of urea. Uric acid is much less soluble than urea and thus requires less water to “flush” out to the system.