The hagfish has one of the most unique defense mechanisms in the animal kingdom. Scientists recently managed to capture fascinating footage of it in use against a shark.
Hagfish are primitive, eel-like creatures that can be found in deep areas of the ocean floor scavenging for decaying animals. They are also blind, jawless, and spineless. When attacked or threatened, however, they exude a gelatinous slime into the water that fill the gills and mouth of potential predators. The slime actually suffocates gilled animals.
You can see the video of the slime being “used” below. The attacking shark quickly gave up after its gills were coated in slime.
Here’s what happens when a human startles a hagfish. As you can tell, the slime is incredible viscous and it would easily deter most predators.