http://www.sciencemag.org/news/2019/01/how-hagfish-launch-slime-missiles-swell-10000-times-size

When a hagfish runs into a hungry shark, the eellike creature squirts out a dollop of goo that—in just a few tenths of a second—expands into a slimy mess 10,000 times its original size, choking the shark and chasing it away. Now, a new study suggests hagfish can’t take all the credit for this gooey defense. Motions in seawater might be the reason the slime can spread into a large cloud so quickly.

Hagfish slime is made up of microscopic pockets of mucus and tightly wound bundles of stringy fiber dubbed “skeins.” When a drop of goo hits the water (above), the skeins inside can unravel into strings several centimeters long in less than half a second.