Have you ever dreamed of flying?

Of gliding effortlessly, propelled only by the slight movements of your own two wings? What if, instead of soaring through the air, you pictured yourself floating through the water?

Because, in the depths of the oceans, about as far from the sky as you can get, there are creatures that do just this, winging their way through the darkness. [[♪♪ INTRO ♪♪]] Welcome back to another journey into the incredible world of the deep sea, a guided tour of footage from our friends at Nautilus Live. Some of the things that we’ve encountered on our ocean explorations have been charming, strange, and even spooky. But these undersea fliers, members of an order of rays called "skates," just, are.

They seem perfectly content to rest on the floor of the ocean or gently glide over it, mostly unbothered by the passing Nautilus ROVs that pause to film them. They come in shades of grays and browns, they can be spotted or mottled, and they occasionally sport dark fins on the ends of their tails. And those fins are one way to tell the difference between a skate and a ray.

Skates tend to have an obvious dorsal fin, while rays usually don’t. And the barbed tails of rays are thinner and more whip-like, equipped with stinging spines. Rays also generally have rounder, flatter heads, while skates have very pointed, triangular heads, topped with a pair of eyes peering off to the sides.

And their round black pupils can be, unsettling. There’s something about them that looks almost human, in a way. But the mind behind them is unknowable to us.

Skates and rays are cousins to sharks, part of a group of cartilaginous fishes called elasmobranchs. And while the gaze of the skate isn’t as intense as that of a shark, there’s something uncomfortably similar about the two. Maybe it comes from this group having ancient roots, with ancestors stretching back hundreds of millions of years.

More recently, if the dinosaurs had ventured into the oceans of the Early Cretaceous period, they could’ve seen skates that looked a lot like these, resting gently on the seafloor or fluttering gracefully by. Or, perhaps they would’ve seen their egg cases washed up on sandy shores. Maybe you’ve even seen them?

The strange, rectangular structures sometimes called "mermaid’s purses." This is another way that skates differ from other kinds of rays. Rays give birth to live young, instead. However they reproduce, though, both are seemingly serene denizens of the undersea world, gliding ever-onward, flying effortlessly toward something only they know.

Before you go, we want to tell you about Study Hall, a Crash Course and Arizona State University collaboration designed to help learners prepare for, succeed at, and graduate college! Their new series, Rhetoric and Composition, breaks down the craft of written communication and teaches you how to write with less stress while effectively accomplishing your goals. New episodes go up every Monday!

Go to YouTube.com/StudyHall to watch and subscribe! Thanks for joining us on this exploration of skates. We’ll be back on the first Friday of next month with another episode of Bizarre Beasts. [[♪♪ OUTRO ♪♪]]