Jellyfish are 95% water, humans 70%, frogs about 80%. What would a cell water content of around 80% mean to a humanoid? It is the size of a human adult with a long tail and some external gills.

For a genetically modified organism made to live amphibiously, how would a higher water content in the cells affect its life? Its skin is more permeable to water, and if it dries out, it will die as do certain amphibians. Would the high water content change its intelligence?

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    $\begingroup$ You're lacking a proper description of your humanoid; without more detail, there's too much unknown for anyone to give you a decent answer. Also, your question could use some more clarity; water content in the cells is not the same as overall composition of the body, and humans being made up of 70% water (which is not always true, incidentally, as that figure tends to drop with age) does not mean that every cell is itself made up of 70% water. $\endgroup$ – Palarran Mar 4 '18 at 17:46
  • $\begingroup$ This is not a trivial question. What determines the water content of a cell? It is a tightly controlled thing but as the OP points out, varies from species to species. $\endgroup$ – Willk Mar 4 '18 at 19:52
  • $\begingroup$ Trivially its physiology would be similar to that of a frog's and especially so if the humanoid was a freshwater organism. It is highly unlikely that a higher water content would have any affect on its intelligence. This is taking a conservative position based on the fact we currently do not know of any relationship between intelligence and cellular water content. Therefore, we can assume there is none (until proven otherwise). $\endgroup$ – a4android Mar 4 '18 at 23:42

The water content of a cell depends on the sort of job the cells does and the intracellular apparatus it uses to do that job. Cell water is not consistent cell to cell within the same organism.

Physiol Chem Phys Med NMR. 2004;36(1):1-19. What determines the normal water content of a living cell? Ling G

In contrast, the PM theory (Theory V) can explain readily the specificity of water content: a specific amount of water accumulates in a specific kind of cell because the free energy of water adsorption on the specific proteins in that type of cells is most favorable. In the PM theory, the quantity and kinds of proteins determine the total amount of water in each type of living cells. Accordingly, the PM theory anticipates that cells serving the same physiological function have similar assortments of proteins — even among different living organisms. On the other hand, cells serving different physiological functions even in the same organism would have different profiles of the kind and amount of proteins. In fact, Ling, Reid and Murphy (1986) have already confirmed this anticipation 18 years ago. Their figures are reproduced here as Figures. 2, 3 and 4..

cell water from various tissues of a frog

Cell water is complicated and interesting but I do not think you can use it alone to explain why your organisms are one way or another.

But: you can state your organism is a certain way and then, if it is that sort of fiction, reference the cell water state as part of that cellular phenotype.


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