Watch a Gulper Eel Inflate Like a Terrifying Balloon

Since launching in 2008, the Ocean Exploration Trust's Nautilus research vessel has live-streamed a purple orb, a transparent squid, and a stubby octopus from the bottom of the ocean. The latest bizarre example of marine life captured by the vessel is a rare gulper eel that acts like a cross between a python and a pufferfish.

As Thrillist reports, this footage was shot by a Nautilus rover roaming the Pacific Ocean's Papahanaumokuakea Marine National Monument 4700 feet below the surface. In it, a limbless, slithery, black creature that looks like it swallowed a beach ball can be seen hovering above the sea floor. After about a minute, the eel deflates its throat, swims around for a bit, and unhinges its jaw to reveal a gaping mouth.

The reaction of the scientists onboard the ship is just as entertaining as the show the animal puts on. At first they're not sure what they're looking at ("It looks like a Muppet," someone says), and after being blown away by its shape-shifting skills, they conclude that it's a gulper eel. Gulper eels are named for their impressive jaw span, which allows them to swallow prey much larger than themselves and puff up to intimidate predators. Because they like to lurk at least 1500 feet beneath the ocean's surface, they're rarely documented.

You can watch the inflated eel and hear the researchers' response to it in the video below.