Why Salt kills earthworms?

A lot of us have become used to using salt to kill earthworms when we encounter any in our houses. I've thought about this for a while now, but I recently decided to check it up and I'll share what I learnt about the science.

Before that, I'll share some points about earthworms:

- They are in the lumbricus genus, there are various species of earthworms, but the common earthworm's scientific name is lumbricus terrestris

- Their digestive system runs through the length of their skin

- Earthworms respire through their skin

- They are hermaphrodites (each one carries both male and female sex organs)

- They lack either an internal skeleton or exoskeleton , but maintain their structure with fluid-filled coelom chambers that function as a hydrostatic skeleton.

Okay, let's talk about salt and earthworms:

Earthworms respire and secrete mucus through their skins. Salt (sodium chloride) has the ability of absorbing moisture (desiccant). When a large quantity of salt is sprinkled around the moist skin of an earthworm, it causes the earthworm to dehydrate (loose water) through the process of osmosis (a process by which water transfers from a region of higher water concentration to that of a lower water concentration through a semipermeable membrane). As the earthworm dehydrates, it ends up dying. If the quantity of salt was very little, it won't cause so much loss of water that would result to the death of the worm.

Photo Credit: tes.com