Why langurs drink salt water | Hacker News Reader

Why langurs drink salt water

nachrichten.idw-online.de

17 pointsgmays28 comments

Frustrating article to read. I think the answer to "why" is implied here:

> This extraordinary ability is a direct consequence of their isolated island home, where there are only limited freshwater sources.

The real answer is: they drink salt water because fresh water is scarce; it's their only option.

I care little for the “why” and more about the “how”.

Incredibly light on just how they are able to drink the salt water.

Google AI result is laughably bad.

> Cat Ba langurs drink salt water by using their tails to sip it. This adaptation helps them survive in their isolated environment on Cat Ba Island in Vietnam, where freshwater sources are limited.

2024 in a nutshell, people.

This Nature paper has more info: https://www.nature.com/articles/s41467-024-52811-7

> The Cat Ba langur also exhibits several unique non-synonymous variants that are related to calcium and sodium metabolism, which may have improved adaptation to high calcium intake and saltwater consumption.

Oh thank you. And the image explains the tail thing more fully. They lick saltwater from their tail.

TIL: Langurs are a genus of monkeys. Only the Cat Ba langur species drinks salt water. Other species are not as endangered.

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

Cat Ba langurs are not cats... The article says they are primates. Not a single photo though.

Hover over the photo at the top, then click the arrow to see the next one.

Direct link to the critter photo: https://nachrichten.idw-online.de/image/399151/screen

My new phone doesn't have a pen anymore, so I can't hover :( Thanks for the direct link!

That link serves a binary file; but has content-type: text/html -- not cool

I see "content-type: image/jpeg" in Firefox's Network Monitor.

Question: How many times can you rewrite the same amount of information into multiple different paragraphs?

DW Online: Yes

I’ve always wondered about ocean mammals. Those poor dolphins and whales have never had a drink of fresh water. When I ask marine biologists, I get: their mouths are really good at sealing - related, but not quite on point, and 2 they get their fresh water from food - to which my reaction is, if I’m really thirty, no amount of salty shrimp are going to satisfy.

Humans aren’t adapted for salt water. We use water evaporation for cooling. Our kidneys don’t minimize water usage.

This adaptation is not limited to marine mammals. Jerboas (Desert rodent) get all of their water from food.

Additionally, most marine mammals don’t eat a diet of shrimp. Fish are much less salty than seawater.

There's also a different way of "getting water from food": methabolizing (burning) carbohidrates with oxygen produces CO2 (carbon dioxyde) and.. water. I think that desert mouse eats very dry grain (which does not contain much water), but does not need to drink water because of that by-product of metabolism.

What do the fish drink?

Fresh water fish need to keep salt in and salt water fish need to push it out. They do this with their gills and kidneys.

Cats can drink a small amounts of salt water, my cat is quite happy drinking our salty swimming pool water.

Why is your swimming pool water salty? Do you fill it from ocean water? I’m asking because most people fill from the municipal water supply which is not salty.

Salted pools are an alternative to chlorinated pools. It's mainly about slowing down the growth of gunk and keeping it clean enough.

It uses a salt water system for sterilisation, is much nicer than chlorine based system - machine does make chlorine from salt but you don't notice it when swimming. No I don't use ocean water, I have a fresh water well then I add about 20 sacks of salt every year.

Why do you have to add more salt? Do you drain the pool regularly? I would imagine the salt stays in the pool when the water evaporates.

Brine pools typically have an electrolysis system that manufactures chlorine from the salt. As such, it’s a salty with low chlorine levels pool, which is still more pleasant than a high-chlorine pool.

I understand what the salt is for. I don’t understand why you have to add more. If the water evaporates the salt remains. And the split sodium and chlorine also recombine. So how does it disapear?

Some pools use a electrolysis system to generate chlorine for the pool. They'are marketed as salt-water chlorinators.

It splits the sodium chloride in the water into chlorine and sodium hydroxide so you don't have to keep buying solid chlorine tablets.

For the electrolysis to work, it needs bout 3000ppm to 5000ppm of salt, for a pool this could be hundreds of pounds of salt.

As an aside, the ocean is about 35000 ppm salt so this is about 1/10th the saltiness of the ocean.

In fact desert cats kidneys are so efficient that supposedly they can survive without directly consuming water. Subsist exclusively on the water from their prey.

My regular cat doesn't drink water if he's eating his raw (wet) food.

That's interesting, but this article is about langurs (which is a type of monkey).

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