This is equal parts disgusting and hypnotic. We’ve seen hippos using their tails to spray their poop around, but we’ve only seen it on land—and the hippo wasn’t pressed right up against glass. Let’s get a look at these fluid dynamics up close.

Ah, the majestic hippo. What we’re seeing up there is actually a very typical behavior, and I don’t just mean the use of the tail to spray poop. When hippos in zoos do this, it’s not a coincidence that they are mostly ass-to-the-audience. This is the hippo showing us who’s boss, and they often give us as clear a view as possible.

One of my favorite zoo memories is of a male hippo in a zoo with the fence right next to his pool. Although the fence was well reinforced, people could lean on it and look at him. Mostly he took no notice, but when he was in the mood, he’d start a show. First he’d open his jaws wide to display his teeth, then he’d roll in the water and toss his head, making huge waves. By this time, everyone in the area was right up against the fence, looking at him. When he had a lot of people near he’d go to the fence, turn around, hike his hips up so his butt was well clear of the edge of the pool, and let fly. You’ve never seen so many people scream and dance backwards in your life. Invariably, there was one kid who didn’t move, and one despairing parent who had to take their hippo-poo-splattered kid home.