Being a spineless bottom-dweller might sound like an insult, but the hagfish has enough unique talents to put humans to shame.

These long, eel-like fish have stellar defenses (blasting predators with slime), impressive offenses (tying themselves in knots), and some truly bizarre bodies (sightless eyes and multiple hearts).

Nearly 80 species of the tentacled deep-sea dwellers exist worldwide, most of which hunt small invertebrates and scavenge carcasses on the seafloor, says Douglas Fudge, a biologist at Chapman University in California.

Recently, fishermen in Bío Bío, Chile, were surprised to catch a hagfish, which they placed on a rock for a closer look.

"We’d never seen anything like it," Lissette Hermosilla, who was part of that group, told National Geographic in an