According to reporting from The New York Times based on a new study published in Ecology and Evolution, scientists have officially documented one of the most desperate survival strategies in nature: a fish fleeing danger by launching itself directly up a manta ray’s butt. All up inside it.

Researchers call the behavior “cloacal diving,” which sounds like a euphemism for an act that’s actually far worse than a fish burrowing into a manta ray’s butt. The pervert fish in question are remoras, those suckerfish that normally spend their lives clinging to sharks, whales, and rays. When threatened, some apparently decide the safest place in the ocean is inside another animal’s butthole.

The study documented seven separate cases between 2010 and 2025 across multiple ocean basins and all three known manta ray species. In several observations, the remora shoved itself so far into the manta ray’s, um, cloaca that only the tip of its tail remained visible, a fish tail turtling out of a manta ray’s rectum the same way you might turtle a little after a bran muffin and a couple of strong morning coffees.

Manta Rays Aren’t Big Fans of Having Fish in Their Butts

Unsurprisingly, the scientists say the manta rays do not appear thrilled to have a fish suddenly slide up their buttholes.

Researchers from the University of Miami described the remoras as being almost exactly as wide as the cloacal opening itself, meaning these fish are basically forcing themselves into what amounts to a living escape hatch that, to the remoras, was seemingly made just for them. In smaller rays, the remora doesn’t even fit completely, leaving half its body hanging out like somebody hiding under a blanket with their feet exposed.

Manta rays and remoras already had a weird relationship. It was always considered mostly harmless, and maybe even beneficial to both species. The remora got transportation and fed on food scraps, while larger animals like manta rays got their parasites cleaned off. Win-win.

But going in through the pooper is decidedly win-lose, at least as far as the researchers can tell. They think the behavior may actually harm manta rays by interfering with the pooping process, reproduction, or damaging the manta rays’ delicate internal tissue.