What makes salt dissolve a snail?

I think this is right.

Water goes to wherever there is proportionately less water. If you put a piece of onion skin in salt water and look at it under a microscope, you’ll see the cells shrink as water leaves them, due to the salt water being proportionately lower in water content than the cells. A snail’s entire (non shell) body is pretty much just a big mucous membrane, so the water behaves the same way as that in an onion skin.

What it does is cause a local hypertonic solution effect that pulls water out of the snail by osmotic effect, in effect shrinking it.

See above. Osmotic pressure

Snails and slugs have no protective skin or shell, so they are vulnerable to the osmotic effects explained above. Central to understanding osmosis is that it requires a semi-permeable membrane that freely passes water but keeps salt and other solute molecules on one side. This peculiar property is (more or less) unique to biological cell membranes.

For the same reason, a living cell immersed in pure water will swell and even burst from osmotic pressure. Normal materials don’t behave this way.

@john65pennington I always wondered too. Thanks for asking.

@gasman |If you put a snail in pure water could you get it to burst too?

I never even knew salt disolves a shell!? I am going to mark this question as great question right know! @ john65pennigton that was a great question and @evereyone who wrote an ansewer for this question wow! youve got some great ansewers!!!!!!!!! lol

@XOIIO Well I haven’t tried, but I doubt it—too little surface-to-volume ratio. Might kill a few surface cells, though, if the water can penetrate the slime.

@tp Salt can’t.