[ryanmarsh]

Funny how our bodies need water and salt, both are in such abundance but in a problematic way.

Max recommended salt intake is less than 1 teaspoon per day. You need 2 liters of water per day. There's nearly 6 teaspoons of salt in 1 liter of sea water. That's quite a bit of excess salt. Kind of a bummer really. Wish we had a gland that got rid of excess salt then we could just drink sea water.

[DuskStar]

> Wish we had a gland that got rid of excess salt then we could just drink sea water.

We've got those - they're called kidneys. Unfortunately, they can't get the output dense enough to be useful for drinking saltwater...

(Maximum saltiness of urine is less than that of saltwater, which is why drinking saltwater dehydrates you)

[SCAQTony]

There is a Sci-fi story somewhere in that comment. i.e., Bioengineered kidney solves some globalize freshwater catastrophe; or does it?

[layoutIfNeeded]

Birds have figured it out:

“Animal metabolism produces about 110 grams of water per 100 grams of fat,[1] 42 grams of water per 100 g of protein and 60 grams of water per 100 g of carbohydrate. [...] In mammals, the water produced from metabolism of protein roughly equals the amount needed to excrete the urea which is a byproduct of the metabolism of protein.[6] Birds, however, excrete uric acid and can have a net gain of water from the metabolism of protein.“

https://en.m.wikipedia.org/wiki/Metabolic_water

[umvi]

> Wish we had a gland that got rid of excess salt then we could just drink sea water.

If such a gland existed, it would probably require a lot of energy to work. Plus, what would the gland do with all of the salt it is filtering just send it to your kidneys/bladder? I'm imagining kidney-stones formed from all the excess salt your body is trying to get rid of

[logfromblammo]

Halophyte plants use a sacrificial salt leaf. They concentrate excess salt into a specific leaf, then cut it loose when it reaches capacity.

The mammalian equivalent would likely be salt hairs.

[solstice]

Wow interesting. Are there any edible such plants? Then their salt leaves could be used as natural seasoning

[logfromblammo]

Salicornia bigelovii is an amaranth, sometimes known as "sea beans", "sea asparagus", or "samphire greens". It is edible, and the seeds are an oil crop. It can grow at 200% the mean salinity of ocean water.

It can grow in seawater, brackish water, or effluent from other agriculture or aquaculture. We should be growing more of it.

Atriplex genus are amaranths called "saltbush"; many are edible directly or usable as livestock forage. Atriplex hortensis is a leaf vegetable, like spinach, often paired with sorrel.

Tetragonia tetragonoides is "sea spinach" and has been cultivated as a leaf vegetable.

Attalea speciosa is an oil palm tree.

Anemopsis californica or "yerba mansa" is used as a medicinal herb.

[solstice]

Oh wow, of course! I know salicorne from vacations in France. Totally forgot about it.

[caymanjim]

Sea mammals manage just fine.

[umvi]

Yeah, because they live underwater and can use said water to flush the waste salt. My question is how a non-water mammal gets rid of the waste salt...

[jacobolus]

A 1 minute web search shows this to be incorrect.

Sea mammals get most of their water from the food they eat (fish, etc.), and don’t drink seawater.

[Retric]

That’s not quite correct, “some marine mammals are known to drink seawater at least on occasion” https://www.scientificamerican.com/article/how-can-sea-mamma...

They do supplement that with water extracted from their food. But unlike humans they are better at expelling salt. “In the seal and sea lion species, for which measurements exist, the animals' urine contains up to two and a half times more salt than seawater does and seven or eight times more salt than their blood.” Human urine on the other hand contains less salt than sea water resulting in dehydration when drinking sea water.

[umvi]

Well then you should be criticizing the person I responded to for suggesting sea mammals have a "gland" that filters salt from water.

[rosser]

> ...for suggesting sea mammals have a "gland" that filters salt from water.

No-one made any such suggestion. One person lamented that such a gland didn't exist; they did not assert its existence. The other person didn't mention glands at all.

[dv_dt]

This begs the question how do fish get water in seawater environments.

[jacobolus]

Another 1 minute web search turns up https://en.wikipedia.org/wiki/Salt_gland https://en.wikipedia.org/wiki/Osmoregulation https://en.wikipedia.org/wiki/Euryhaline