How do hagfish defend themselves?

The hagfish might seem like an innocent-looking eel, but this 300-million-year-old, soft-skinned fish has survived the test of time due to a deadly – not to mention utterly revolting – self-defence mechanism. The hagfish has no scales, jaw, venom or spinal column, but it has the power to suffocate its enemies in a flash with the help of a choking slime squirted from vesicles down the length of its body. In fact, the hagfish can ‘slime’ a predator in under half a second.
When the fish is physically disturbed – by a strike from an attacker, for example – the slime gland is triggered to shoot out mucus proteins called mucins, which when combined with seawater immediately turn into a thick goo.