Remoras Are Diving Into Manta Ray “Buttholes.” Really.

InnovationScienceRemoras Are Diving Into Manta Ray “Buttholes.” Really.ByMelissa Cristina Márquez,Contributor.Forbes contributors publish independent expert analyses and insights. Márquez is a marine scientist and science communicatorFollow AuthorMay 12, 2026, 07:21am EDT--:-- / --:--This voice experience is generated by AI. Learn more.This voice experience is generated by AI. Learn more.New observations of remoras diving into the cloacas and gill slits of manta rays suggest these relationships may be far more invasive, and complicated, than scientists once thought.Provided by Catherine McdonaldThe first time most people notice a remora, it is usually attached to something much bigger. Maybe it is riding along the belly of a shark in a nature documentary or stuck to the underside of a manta ray gliding through the azure water like some sort of ethereal, living spaceship. There is sometimes one, sometimes many. And looking quite unassuming, they are often treated as comic relief in the ocean world, lovingly known as “little hitchhikers” for their tendency to catch a free ride on whatever (un)willing bigger animal. But the deeper scientists look at these fish, the stranger the story becomes.A new study documenting remora behavior in manta rays reveals interactions that are far more intimate, and potentially harmful, than many researchers expected! Led by PhD student Emily A. Yeager of the Shark Research and Conservation Program at the University of Miami, a team of scientists recorded seven observations of remoras engaging in what is known as “cloacal diving behavior” in manta rays across all three known manta species (the reef manta ray, the giant oceanic manta ray and the Atlantic manta ray) and across multiple ocean basins. In simple terms, the remoras were entering the cloaca of the ray, an opening used for digestion and reproduction.Yes, really. That hole. The “butt hole.”And as if that wasn’t invasive enough, researchers also documented remoras attaching beneath...