Here's why:
* Salt is common: Salt is found naturally in the environment, and many animals live in salty environments (like oceans or deserts).
* It's about concentration: The problem with salt is when it's too concentrated. Too much salt can disrupt the animal's internal balance of fluids and electrolytes, leading to dehydration and other health problems.
* Examples:
* Slugs and snails: Salt dehydrates them because it draws out the moisture from their bodies.
* Some insects: Salt can be toxic to certain insects in high concentrations.
* Saltwater fish: These fish have adapted to live in a salty environment, but they can't survive in freshwater.
So, it's not the salt itself that's fatal, but rather the disruption it causes to the animal's body functions when in excess.