A new video posted by SmarterEveryDay explains how jellyfishes’ tentacles are equipped with organelles called nematocysts that extend whenever they come into contact with something else and inject venom directly into it.
To give us a demonstration of this, there's amazing microscopic slow-motion footage of jellyfish tentacles that get stimulated with electricity a 9-volt battery. Once the tentacles get touched, we can see tiny little prickers protrude from them that would injected venom into your hand if you touched them yourself.
And this explains why jellyfish stings hurt so incredibly much: They’re basically a bunch of tiny microscopic knives that are stabbing you all at once and flooding your body with a painful chemical. Watch the amazing video below.