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Study Documents Remoras Inserting Themselves Into Manta Rays' Cloacas

The peer‑reviewed paper flags possible risks to manta reproduction and waste expulsion.

Overview

  • Marine biologists reporting in Ecology and Evolution verified seven cases of this behavior across surveys from 2010 to 2025 involving all three known manta species.
  • A freediver’s video from Florida showed a remora startling, entering an Atlantic manta ray’s cloacal opening, and the ray shuddering before swimming off with the fish still inside.
  • Authors warn that a fish lodged in the cloaca could block mating, live birth, or defecation if the intrusion lasts, suggesting real harm to the host.
  • The sightings span multiple ocean basins, including records from the Maldives, Mozambique, and Florida, yet they remain rare in thousands of surveys.
  • Evidence so far comes from photos and short clips, so scientists cannot tell how often or how long it happens, why it occurs, or whether it shifts a usually benign hitchhiker relationship toward parasitism.