Tidepool Tim says,  “These primitive animals are from the pre-jaw era of agnathans! They are a relic of ancient times. They may be quite disgusting, but their abilities are awe-inspiring for several reasons. For example, when predators attack them, they secrete slime at a rate of 4 cups in less than a second! The slime is a mix of fibers and mucus that clog the predator’ gills every time.

Hagfish are the only animal in the kingdom with a cranium, but no spinal column. This fish is an early “chordate,” animals with notochords (or spinal column + notochord remnants, like humans). Hagfish can also escape a predator’s mouth by tying itself into a knot! The knot shape is also used to leverage their weight when feeding on a big, dead prey item.

Maybe even more amazing, hagfish hearts can beat for three hours with absolutely no oxygen, using fats instead!”