The slug contains a lot of water, which is essential for its survival. Sprinkling with salt draws that water out, and the poor creature dies of dehydration.
Osmosis is a natural biological phenomenon whereby water passes from one region of high water concentration, through a semi permeable membrane to a region of lower water concentration.
Salt is a desiccant, meaning that it absorbs water from things. That’s why consuming an excess of it makes you feel thirsty. So when applied to the moist surface of a slug, it immediately sucks up water from its skin, which is far more permeable than the skin of most other animals.
The process of osmosis is triggered and large amounts of fluid from inside the slug rush to the surface to restore equilibrium and dilute the concentration of salt. This results in the thick goo you see.
The unfortunate slug rapidly loses more fluid than it can tolerate, and quickly dies from dehydration. Personally I think this sounds a particularly tortuous way to die, even for a slug.
It doesn't burn.
The salt draws out the moisture from the slug and it basically dies of dehydration.
There is no protection to the slug other than the slime. The salt draws moisture from the critter drying it out.
The salt is broken down by the slug watery slime. A product of this is an acid
I use salt water (saline solution) for medicinal purposes, as a disinfectant, nose drops, as a food preservative with olives, and for eye problems (to suck out moisture when there is too much) like Fuchs' Dystrophy. I use beer to kill slugs--they get drunk and die by drowning.
I was wondering as to why when one pours salt on a slug's flesh, it burns? I would never harm any creature in such a way, but I was wondering why it happens.
