What does it take to survive on Earth for 300 million years?

The secret might just be the ability to ooze slime from your pores. The defense tactic has worked for the hagfish, an eel-like animal that looks like an oversized tapeworm. (Exactly how to classify the hagfish—also called slime eels—is debated among scientists, who see it as either a vertebrate or invertebrate.)

When a predator chomps down on the creature, it releases slime made of mucus proteins that expand when mixed with saltwater. The slime sets quickly, often choking whatever unlucky predator has grasped a hagfish. In case slime doesn't do the trick, hagfish also have a nightmarish four rows of large, jagged teeth, which they can use to take