The hagfish is one of those animals that scientists aren’t quite sure how to classify. These bottom-feeders have a skull but no backbone. Like lampreys, they have no jaw, but then lampreys do have vertebrae. Hagfish look like eels, but with naked skin instead of scales. They can survive up to 36 hours without oxygen — while their hearts keep beating — and they’ve been around for more than 350 million years, long, long before the first dinosaurs ever walked the Earth.
In Print: July 1, 2016